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A major roadblock in implementing engineered tissues clinically lies in their limited vascularization. After implantation, such tissues do not integrate with the hostʼs circulation as quickly as needed, commonly resulting in loss of viability and functionality. This study presents a solution to the vascularization problem that could enable the survival and function of large, transplantable, and vascularized engineered tissues. The technique allows vascularization of a cell laden hydrogel through angiogenesis from a suturable tissue-engineered vascular graft (TEVG) constructed from electrospun polycaprolactone with macropores. The graft is surrounded by a layer of cell-laden gelatin-methacryloyl hydrogel. The constructs are suturable and possess mechanical properties like native vessels. Angiogenesis occurs through the pores in the graft, resulting in a hydrogel containing an extensive vascular network that is connected to an implantable TEVG. The size of the engineered tissue and the degree of vascularization can be increased by adding multiple TEVGs into a single construct. The engineered tissue has the potential to be immediately perfused by the patient's blood upon surgical anastomosis to host vessels, enabling survival of implanted cells. These findings provide a meaningful step to address the longstanding problem of fabricating suturable pre-vascularized tissues which could survive upon implantation in vivo. Creating vascularized engineered tissues that can be transplanted and rapidly perfused by the host blood supply is a major challenge which has limited the clinical impact of tissue engineering. In this study we demonstrate a technique to fabricate vascularized tissue constructs via angiogenesis from a suturable tissue-engineered vascular graft. The macroporous graft is surrounded with hydrogel, allowing endothelial cells to migrate from the lumen and vascularize the hydrogel layer with capillary-like structures connected to the macrovessel. The graft has comparable mechanical properties to native blood vessels and larger constructs can be fabricated by incorporating multiple grafts. These constructs could potentially be connected surgically to the circulation at an implantation site to support their immediate perfusion and survival. [Display omitted] [ABSTRACT FROM AUTHOR]

Traditional adhesive hydrogels perform well in tissue adhesion but they fail to prevent postoperative tissue adhesion. To address this challenge, a biodegradable Janus adhesive hydrogel (J-AH) was designed and fabricated by the assembly of three different functional layers including anti-adhesive layer, reinforceable layer, and wet tissue adhesive layer. Each layer of J-AH serves a specific function: the top zwitterionic polymeric anti-adhesive layer shows superior resistance to cell/protein and tissue adhesion; the middle poly(vinyl alcohol)/tannic acid reinforceable matrix layer endows the hydrogel with good mechanical toughness of ∼2.700 MJ/m3; the bottom poly(acrylic acid)/polyethyleneimine adhesive layer imparts tough adhesion (∼382.93 J/m2 of interfacial toughness) to wet tissues. In the rat liver and femoral injury models, J-AH could firmly adhere to the bleeding tissues to seal the wounds and exhibit impressive hemostatic efficiency. Moreover, in the in vivo adhesion/anti-adhesion assay of J-AH between the defected cecum and peritoneal walls, the top anti-adhesive layer can effectively inhibit undesired postoperative abdominal adhesion and inflammatory reaction. Therefore, this research may present a new strategy for the design of advanced bio-absorbable Janus adhesive hydrogels with multi-functions including tissue adhesion, anti-postoperative adhesion and biodegradation. Despite many adhesive hydrogels with tough tissue adhesion capability have been reported, their proclivity for undesired postoperative adhesion remains a serious problem. The postoperative adhesion may lead to major complications and even endanger the lives of patients. The injectable hydrogels can cover the irregular wound and suppress the formation of postoperative adhesion. However, due to the lack of adhesive properties with tissue, it is difficult for the hydrogels to maintain on the wound surface, resulting in poor anti-postoperative adhesion effect. Herein, we design a Janus adhesive hydrogel (J-AH). J-AH integrates together robust wet tissue adhesion and anti-postoperative adhesion. Therefore, this research may present a new strategy for the design of advanced bio-absorbable Janus adhesive hydrogels. [Display omitted] [ABSTRACT FROM AUTHOR]

The extracellular matrix protein collagen I has been used extensively in the field of biomaterials due to its inherent biocompatibility and unique viscoelastic and mechanical properties. Collagen I self-assembly into fibers and networks is environmentally sensitive to gelation conditions such as temperature, resulting in gels with distinct network architectures and mechanical properties. Despite this, collagen gels are not suitable for many applications given their relatively low storage modulus. We have prepared collagen-poly(ethylene glycol) [PEG] interpenetrating network (IPN) hydrogels to reinforce the collagen network, which also induces changes to network plasticity, a recent focus of study in cell-matrix interactions. Here, we prepare collagen/PEG IPNs, varying collagen concentration and collagen gelation temperature to assess changes in microarchitecture and mechanical properties of these networks. By tuning these parameters, IPNs with a range of stiffness, plasticity and pore size are obtained. Cell studies suggest that matrix plasticity is a key determinant of cell behavior, including cell elongation, on these gels. This work presents a natural/synthetic biocompatible matrix that retains the unique structural properties of collagen networks with increased storage modulus and tunable plasticity. The described IPN materials will be of use for applications in which control of cell spreading is desirable, as only minimal changes in sample preparation lead to changes in cell spreading and circularity. Additionally, this study contributes to our understanding of the connection between collagen self-assembly conditions and matrix structural and mechanical properties and presents them as useful tools for the design of other collagen based biomaterials. We developed a collagen-poly(ethylene glycol) interpenetrating network (IPN) platform that retains native collagen architecture and biocompatibility but provides higher stiffness and tunable plasticity. With minor changes in collagen gelation temperature or concentration, IPN gels with a range of plasticity, storage modulus, and pore size can be obtained. The tunable plasticity of the gels is shown to modulate cell spreading, with a greater proportion of elongated cells on the most plastic of IPNs, supporting the assertion that matrix plasticity is a key determinant of cell spreading. The material can be of use for situations where control of cell spreading is desired with minimal intervention, and the findings herein may be used to develop similar collagen based IPN platforms. [Display omitted] [ABSTRACT FROM AUTHOR]

Hypothermic preservation (HP) is highly desired for the maintenance of the viability of living cell specimens, e.g. rare cells in whole-blood samples or therapeutic cells, in an unfrozen state. However, the extension of the viable preservation time is a challenge because of the multiple injuries suffered by hypothermically preserved cells. Here, based on a dynamic bond crosslinked zwitterionic hydrogel, we established a sensing preservation system that could monitor the levels of reactive oxygen species (ROS) via real-time electronic signals and intelligent control of antioxidant addition, to completely prevent an excess of ROS in the whole-cell specimen. Furthermore, the hydrogel-based system can counter the extracellular-matrix-loss-induced anoikis of living cells. Based on the design aimed at affording protection against two primary HP injuries (i.e. ROS overproduction and anoikis) to cells, this system extended the preservation time of cell specimens under refrigerated conditions to 24 days. After preservation, the use of a mild cell retrieval process guaranteed the activity of the preserved living cells. This work not only possesses the potential to facilitate intelligent cell-based clinical applications, but also paves the way for the preparation of living materials that can host programmed cells with long-term survival. An intelligent system based on a zwitterionic sensing hydrogel is established, which can afford ultra-long hypothermic cell-preservation times of up to 24 days. The system enables the real-time monitoring of ROS overproduction and intelligent antioxidant addition, because of the merging of the smart hydrogel with a computer intelligent detection and control system. Furthermore, the automatic addition of an antioxidant according to the ROS-signal changes produced by the ZBA hydrogel effectively prevented HP lesions, including ROS over-production and ECM loss, in the preserved living cells. Subsequently, the system could also be gently dissociated, to retrieve the preserved cells. This work provides a solution for the real-time monitoring and long-term HP of living specimens, which holds the promise of benefiting cell-based medicine and the development of genetically programmed cell-based living materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Postoperative abdominal adhesion (PAA) widely occurs after abdominal surgery, which often produces severe complications. However, there were still no satisfactory anti-adhesive products including barriers and anti-adhesive agents. Herein, we developed a ROS-responsive and scavenging hydrogel barrier, termed AHBC/PSC, wherein the monomer AHBC was synthesized by phenylboronic acid (PBA)-modified hyaluronic acid (HA-PBA) further grafted with adipic dihydrazide (ADH) and PBA-based chlorogenic acid (CGA) via ROS-sensitive borate ester bond, and the other monomer PSC was constructed by polyvinyl alcohol (PVA) grafted with sulfated betaine (SB) and p-hydroxybenzaldehyde (CHO). Further, the double crosslinked AHBC/PSC hydrogel was successfully fabricated between AHBC and PSC via forming dynamic covalent acylhydrazone bonds and borate ester bonds. Results showed that AHBC/PSC hydrogel had in situ gelation behavior, satisfactory mechanical properties (storage modulus of about 1 kPa and loss factor Tan δ of about 0.5), suitable wet tissue adhesion strength of about 2.3 kPa on rat abdominal wall, and good biocompatibility, achieving an ideal physical barrier. Particularly, CGA could be responsively released from the hydrogel by breakage of borate ester bonds between CGA and PBA based on high reactive oxygen species (ROS) levels of damaged tissue and exhibited great ROS scavenging capability to regulate inflammation and promote the polarization of macrophages from pro-inflammatory M1 phenotype to anti-inflammatory M2 phenotype. Moreover, the grafted SB as a zwitterionic group could reduce protein adsorption and fibroblast adhesion. Finally, the in vivo experiments revealed that AHBC/PSC hydrogel with good safety and in vivo retention behavior of about 2 weeks, effectively prevented PAA by regulating the inflammatory microenvironment and alleviating the fibrosis process. In brief, the versatile AHBC/PSC hydrogel would provide a more convenient and efficient approach for PAA prevention. Postoperative abdominal adhesion (PAA) widely occurs after surgery and is often accompanied by severe complications. Excessive inflammation and oxidative stress are very crucial for PAA formation. This study provides a ROS-responsive and scavenging hydrogel with suitable mechanical properties, good biocompatibility and biodegradability, and resistance to protein and fibroblast. The antioxidant and anti-inflammatory active ingredient could be responsively released from the hydrogel via triggering by the high ROS levels in the postoperative microenvironment thereby regulating the inflammatory balance. Finally, the hydrogel would effectively regulate the development process of PAA thereby achieving non-adhesion wound healing. [Display omitted] [ABSTRACT FROM AUTHOR]

Surgical meshes play a significant role in the treatment of various medical conditions, such as hernias, pelvic floor issues, guided bone regeneration, and wound healing. To date, commercial surgical meshes are typically made of non-absorbable synthetic polymers, notably polypropylene and polytetrafluoroethylene, which are associated with postoperative complications, such as infections. Biological meshes, based on native tissues, have been employed to overcome such complications, though mechanical strength has been a main disadvantage. The right balance in mechanical and biological performances has been achieved by the advent of bioresorbable meshes. Despite improvements, recurrence of clinical complications associated with surgical meshes raises significant concerns regarding the technical adequacy of current materials and designs, pointing to a crucial need for further development. To this end, current research focuses on the design of meshes capable of biomimicking native tissue and facilitating the healing process without post-operative complications. Researchers are actively investigating advanced bioresorbable materials, both synthetic polymers and natural biopolymers, while also exploring the performance of therapeutic agents, surface modification methods and advanced manufacturing technologies such as 4D printing. This review seeks to evaluate emerging biomaterials and technologies for enhancing the performance and clinical applicability of the next-generation surgical meshes. In the ever-transforming landscape of regenerative medicine, the embracing of engineered bioabsorbable surgical meshes stands as a key milestone in addressing persistent challenges and complications associated with existing treatments. The urgency to move beyond conventional non-absorbable meshes, fraught with post-surgery complications, emphasises the necessity of using advanced biomaterials for engineered tissue regeneration. This review critically examines the growing field of absorbable surgical meshes, considering their potential to transform clinical practice. By strategically combining mechanical strength with bioresorbable characteristics, these innovative meshes hold the promise of mitigating complications and improving patient outcomes across diverse medical applications. As we navigate the complexities of modern medicine, this exploration of engineered absorbable meshes emerges as a promising approach, offering an overall perspective on biomaterials, technologies, and strategies adopted to redefine the future of surgical meshes. [Display omitted] [ABSTRACT FROM AUTHOR]

Bacterial infections are a serious threat to wound healing and skin regeneration. In recent years, photothermal therapy (PTT) has become one of the most promising tools in the treatment of infectious diseases. However, wound dressings with photo-responsive properties are currently still limited by the difficulties of biosafety and thermal stability brought by the introduction of photosensitizers or photothermal agents. Therefore, how to improve the therapeutic efficiency and biosafety from material design is still a major challenge at present. In this study, the carboxymethyl chitosan (CMCS) and protocatechuic aldehyde (PA) hydrogels based on horseradish peroxidase (HRP) and hydrogen peroxide (H 2 O 2) enzymatic catalysis was developed. Therein, HRP and H 2 O 2 catalyzed cross-linking while polymerizing PA, which not only endowed the hydrogels with photothermal responsiveness but also with good biosafety through this enzyme-catalyzed green approach. Meanwhile, the hydrogels possessed highly efficient bacteriostatic ability with the assistance of near infrared (NIR). Moreover, the ultra-rapid gelation, strong tissue adhesion, high swelling ability, good antioxidant property and hemostatic property of the CMCS-PA hydrogels based on HRP/H 2 O 2 enzymatic catalysis were suitable for the treatment of skin wounds. Meanwhile, NIR-assistant CMCS-PA hydrogels based on HRP/H 2 O 2 enzymatic catalysis reduced inflammation, decreased bacterial infection, and promoted collagen deposition and angiogenesis, which showed remarkable therapeutic effects in a skin wound infection model. All results indicate that this green approach to introduce photothermal property by HRP-catalyzed PA polymerization endows the hydrogels with efficient photothermal conversion efficiency, suggesting that they are promising to provide new options for replacing photothermal agents and photosensitizers. In recent years, wound dressings with photo-responsive properties are currently still limited by the difficulties of biosafety and thermal stability brought by the introduction of agent photosensitizers or photothermal agents. In this study, the carboxymethyl chitosan and protocatechuic aldehyde hydrogels based on horseradish peroxidase and hydrogen peroxide enzymatic catalysis was developed. The photothermal properties of hydrogels were transformed from absent to present just by horseradish peroxidase-catalyzed protocatechuic aldehyde polymerization in a green approach. Meanwhile, the hydrogels possessed highly efficient bacteriostatic ability with the assistance of near infrared. The green approach of introducing photothermal properties from material design solves the biosafety challenge. Therefore, this study is expected to provide new options for alternative photothermal agents and photosensitizers. [Display omitted] [ABSTRACT FROM AUTHOR]

Achieving precise spatiotemporal control over the release of proangiogenic factors is crucial for vasculogenesis, the process of de novo blood vessel formation. Although various strategies have been explored, there is still a need to develop cell-laden biomaterials with finely controlled release of proangiogenic factors at specific locations and time points. We report on the developed of a near-infrared (NIR) light-responsive collagen hydrogel comprised of gold nanorods (GNRs)-conjugated liposomes containing proangiogenic growth factors (GFs). We demonstrated that this system enables on-demand dual delivery of GFs at specific sites and over selected time intervals. Liposomes were strategically formulated to encapsulate either platelet-derived growth factor (PDGF) or vascular endothelial growth factor (VEGF), each conjugated to gold nanorods (GNRs) with distinct geometries and surface plasmon resonances at 710 nm (GNR710) and 1064 nm (GNR1064), respectively. Using near infrared (NIR) irradiation and two-photon (2P) luminescence imaging, we successfully demonstrated the independent release of PDGF from GNR710 conjugated liposomes and VEGF from GNR1064-conjugated liposomes. Our imaging data revealed rapid release kinetics, with localized PDGF released in approximately 4 min and VEGF in just 1 and a half minutes following NIR laser irradiation. Importantly, we demonstrated that the release of each GF could be independently triggered using NIR irradiation with the other GF formulation remaining retained within the liposomes. This light-responsive collagen hydrogels holds promise for various applications in regenerative medicine where the establishment of a guided vascular network is essential for the survival and integration of engineered tissues. In this study, we have developed a light-responsive system with gold nanorods (GNRs)-conjugated liposomes in a collagen hydrogel, enabling precise dual delivery of proangiogenic growth factors (GFs) at specific locations and timepoints. Liposomes, containing platelet-derived growth factor (PDGF) or vascular endothelial growth factor (VEGF), release independently under near- infrared irradiation. This approach allows external activation of desired GF release, ensuring high cell viability. Each GF can be triggered independently, retaining the other within the liposomes. Beyond its application in establishing functional vascular networks, this dual delivery system holds promise as a universal platform for delivering various combinations of two or more GFs. [Display omitted] [ABSTRACT FROM AUTHOR]

Controlled release of low molecular weight hydrophilic drugs, administered locally, allows maintenance of high concentrations at the target site, reduces systemic side effects, and improves patient compliance. Injectable hydrogels are commonly used as a vehicle. However, slow release of low molecular weight hydrophilic drugs is very difficult to achieve, mainly due to a rapid diffusion of the drug out of the drug delivery system. Here we present an injectable and self-healing hydrogel based entirely on the self-assembly of liposomes. Gelation of liposomes, without damaging their structural integrity, was induced by modifying the cholesterol content and surface charge. The small hydrophilic molecule, sodium fluorescein, was loaded either within the extra-liposomal space or encapsulated into the aqueous cores of the liposomes. This encapsulation strategy enabled the achievement of controlled and adjustable release profiles, dependent on the mechanical strength of the gel. The hydrogel had a high mechanical strength, minimal swelling, and slow degradation. The liposome-based hydrogel had prolonged mechanical stability in vivo with benign tissue reaction. This work presents a new class of injectable hydrogel that holds promise as a versatile drug delivery system. The porous nature of hydrogels poses a challenge for delivering small hydrophilic drug, often resulting in initial burst release and shorten duration of release. This issue is particularly pronounced with physically crosslinked hydrogels, since their matrix can swell and dissipate rapidly, but even in cases where the polymers in the hydrogel are covalently cross-linked, small molecules can be rapidly released through its porous mesh. Here we present an injectable self-healing hydrogel based entirely on the self-assembly of liposomes. Small hydrophilic molecules were entrapped inside the extra-liposomal space or loaded into the aqueous cores of the liposomes, allowing controlled and tunable release profiles. [Display omitted] [ABSTRACT FROM AUTHOR]

Self-assembling peptide-based hydrogels have become a highly attractive scaffold for three-dimensional (3D) in vitro disease modeling as they provide a way to create tunable matrices that can resemble the extracellular matrix (ECM) of various microenvironments. Alzheimer's disease (AD) is an exceptionally complex neurodegenerative condition; however, our understanding has advanced due to the transition from two-dimensional (2D) to 3D in vitro modeling. Nonetheless, there is a current gap in knowledge regarding the role of amyloid structures, and previously developed models found long-term difficulty in creating an appropriate model involving the ECM and amyloid aggregates. In this report, we propose a multi-component self-assembling peptide-based hydrogel scaffold to mimic the amyloid-beta (β) containing microenvironment. Characterization of the amyloid-β-mimicking hydrogel (Col-HAMA-FF) reveals the formation of β-sheet structures as a result of the self-assembling properties of phenylalanine (Phe, F) through π−π stacking of the residues, thus mimicking the amyloid-β protein nanostructures. We investigated the effect of the amyloid-β-mimicking microenvironment on healthy neuronal progenitor cells (NPCs) compared to a natural-mimicking matrix (Col-HAMA). Our results demonstrated higher levels of neuroinflammation and apoptosis markers when NPCs were cultured in the amyloid-like matrix compared to a natural brain matrix. Here, we provided insights into the impact of amyloid-like structures on NPC phenotypes and behaviors. This foundational work, before progressing to more complex plaque models, provides a promising scaffold for future investigations on AD mechanisms and drug testing. In this study, we engineered two multi-component hydrogels: one to mimic the natural extracellular matrix (ECM) of the brain and one to resemble an amyloid-like microenvironment using a self-assembling peptide hydrogel. The self-assembling peptide mimics β-amyloid fibrils seen in amyloid-β protein aggregates. We report on the culture of neuronal progenitor cells within the amyloid-mimicking ECM scaffold to study the impact through marker expressions related to inflammation and DNA damage. This foundational work, before progressing to more complex plaque models, offers a promising scaffold for future investigations on AD mechanisms and drug testing. [Display omitted] [ABSTRACT FROM AUTHOR]

Large skin injuries heal as scars. Stiffness gradually increases from normal skin to scar tissue (20x higher), due to excessive deposition and crosslinking of extracellular matrix (ECM) mostly produced by (myo)fibroblasts. Using a custom mold, skin-derived ECM hydrogels (dECM) were UV crosslinked after diffusion of ruthenium (Ru) to produce a Ru-dECM gradient hydrogel. The Ru diffusion gradient equates to a stiffness gradient and models physiology of the scarred skin. Crosslinking in Ru-dECM hydrogels results in a 23-fold increase in stiffness from a stiffness similar to that of normal skin. Collagen fiber density increases in a stiffness-dependent fashion while stress relaxation also alters, with one additional Maxwell element necessary for characterizing Ru-dECM. Alignment of fibroblasts encapsulated in hydrogels suggests that the stiffness gradient directs fibroblasts to orientate at ∼45 ° in regions below 120 kPa. In areas above 120 kPa, fibroblasts decrease the stiffness prior to adjusting their orientation. Furthermore, fibroblasts remodel their surrounding ECM in a gradient-dependent fashion, with rearrangement of cell-surrounding ECM in high-stiffness areas, and formation of interlaced collagen bundles in low-stiffness areas. Overall, this study shows that fibroblasts remodel their local environment to generate an optimal ECM mechanical and topographical environment. This study developed a versatile in vitro model with a gradient stiffness using skin-derived ECM hydrogel with unchanged biochemical environment. Using Ruthenium crosslinking, a 20-fold stiffness increase was achieved as observed in fibrotic skin. The interaction between fibroblasts and matrix depends on changes in the matrix stiffness. The stiffness gradient directed the alignment of fibroblasts with ∼45° in regions with≤ 120 kPa. The cells in regions with the higher stiffness decreased stiffness first and then oriented themselves. Furthermore, fibroblasts remodeled surrounding ECM and regulated its mechanics in a gradient-dependent fashion to reach an optimal condition. Our study highlights the dynamic interplay between cells and surrounding matrix, shedding light on potential mechanisms and strategies to target scar formation and remodeling. [Display omitted] [ABSTRACT FROM AUTHOR]

Bacterial infections are among the most critical global health challenges that seriously threaten the security of human. To address this issue, a biocompatible engineered living hydrogel patch was developed by co-embedding engineered photothermal bacteria (EM), photosensitizer (porphyrin) and reactive oxygen species amplifier (laccase) in a protein hydrogel. Remarkably, the genetice engineered bacteria can express melanin granules in vivo and this allows them to exhibit photothermal response upon being exposed to NIR-II laser (1064 nm) irradiation. Besides, electrostatically adhered tetramethylpyridinium porphyrin (TMPyP) on the bacterial surface and encapsulated laccase (Lac) in protein gel can generate highly toxic singlet oxygen (1O 2) and hydroxyl radical (·OH) in the presence of visible light and lignin, respectively. Interestingly, the engineered bacteria hydrogel patch (EMTL@Gel) was successfully applied in synergistic photothermal, photodynamic and chemodynamic therapy, in which it was able to efficiently treat bacterial infection in mouse wounds and enhance wound healing. This work demonstrates the concept of "fighting bacteria with bacteria" combining bacterial engineering and material engineering into an engineered living hydrogel path that can synergistically boost the therapeutic outcome. Genetically engineered bacteria produce melanin granules in vivo , exhibiting remarkable photothermal properties. These bacteria, along with a photosensitizer (TMPyP) and a reactive oxygen species amplifier (laccase), are incorporated into a biocompatible protein hydrogel patch. Under visible light, the patch generates toxic singlet oxygen (1O 2) and hydroxyl radical (·OH), demonstrates outstanding synergistic effects in photothermal, photodynamic, and chemodynamic therapy, effectively treating bacterial infections and promoting wound healing in mice. [Display omitted] [ABSTRACT FROM AUTHOR]

Bacterial infection poses a significant impediment in wound healing, necessitating the development of dressings with intrinsic antimicrobial properties. In this study, a multilayered wound dressing (STPU@MTAI 2 /AM 1) was reported, comprising a surface-superhydrophobic treated polyurethane (STPU) sponge scaffold coupled with an antimicrobial hydrogel. A superhydrophobic protective outer layer was established on the hydrophilic PU sponge through the application of fluorinated zinc oxide nanoparticles (F-ZnO NPs), thereby resistance to environmental contamination and bacterial invasion. The adhesive and antimicrobial inner layer was an attached hydrogel (MTAI 2 /AM 1) synthesized through the copolymerization of N -[2-(methacryloyloxy)ethyl]- N, N, N -trimethylammonium iodide and acrylamide, exhibits potent adherence to dermal surfaces and broad-spectrum antimicrobial actions against resilient bacterial strains and biofilm formation. STPU@MTAI 2 /AM 1 maintained breathability and flexibility, ensuring comfort and conformity to the wound site. Biocompatibility of the multilayered dressing was demonstrated through hemocompatibility and cytocompatibility studies. The multilayered wound dressing has demonstrated the ability to promote wound healing when addressing MRSA-infected wounds. The hydrogel layer demonstrates no secondary damage when peeled off compared to commercial polyurethane sponge dressing. The STPU@MTAI 2 /AM 1 -treated wounds were nearly completely healed by day 14, with an average wound area of 12.2 ± 4.3 %, significantly lower than other groups. Furthermore, the expression of CD31 was significantly higher in the STPU@MTAI 2 /AM 1 group compared to other groups, promoting angiogenesis in the wound and thereby contributing to wound healing. Therefore, the prepared multilayered wound dressing presents a promising therapeutic candidate for the management of infected wounds. Healing of chronic wounds requires avoidance of biofouling and bacterial infection. However developing a wound dressing which is both anti-biofouling and antimicrobial is a challenge. A multilayered wound dressing with multifunction was developed. Its outer layer was designed to be superhydrophobic and thus anti-biofouling, and its inner layer was broad-spectrum antimicrobial and could inhibit biofilm formation. The multilayered wound dressing with adhesive property could easily be removed from the wound surface preventing the cause of secondary damage. The multilayered wound dressing has demonstrated good abilities to promote MRSA-infected wound healing and presents a viable treatment for MRSA-infected wound. [Display omitted] [ABSTRACT FROM AUTHOR]

Dental pulp is the only soft tissue in the tooth which plays a crucial role in maintaining intrinsic multi-functional behaviors of the dentin-pulp complex. Nevertheless, the restoration of fully functional pulps after pulpitis or pulp necrosis, termed endodontic regeneration, remained a major challenge for decades. Therefore, a bioactive and in-situ injectable biomaterial is highly desired for tissue-engineered pulp regeneration. Herein, a decellularized matrix hydrogel derived from porcine dental pulps (pDDPM-G) was prepared and characterized through systematic comparison against the porcine decellularized nerve matrix hydrogel (pDNM-G). The pDDPM-G not only exhibited superior capabilities in facilitating multi-directional differentiation of dental pulp stem cells (DPSCs) during 3D culture, but also promoted regeneration of pulp-like tissues after DPSCs encapsulation and transplantation. Further comparative proteomic and transcriptome analyses revealed the differential compositions and potential mechanisms that endow the pDDPM-G with highly tissue-specific properties. Finally, it was realized that the abundant tenascin C (TNC) in pDDPM served as key factor responsible for the activation of Notch signaling cascades and promoted DPSCs odontoblastic differentiation. Overall, it is believed that pDDPM-G is a sort of multi-functional and tissue-specific hydrogel-based material that holds great promise in endodontic regeneration and clinical translation. Functional hydrogel-based biomaterials are highly desirable for endodontic regeneration treatments. Decellularized extracellular matrix (dECM) preserves most extracellular matrix components of its native tissue, exhibiting unique advantages in promoting tissue regeneration and functional restoration. In this study, we prepared a porcine dental pulp-derived dECM hydrogel (pDDPM-G), which exhibited superior performance in promoting odontogenesis, angiogenesis, and neurogenesis of the regenerating pulp-like tissue, further showed its tissue-specificity compared to the peripheral nerve-derived dECM hydrogel. In-depth proteomic and transcriptomic analyses revealed that the activation of tenascin C-Notch axis played an important role in facilitating odontogenic regeneration. This biomaterial-based study validated the great potential of the dental pulp-specific pDDPM-G for clinical applications, and provides a springboard for research strategies in ECM-related regenerative medicine. [Display omitted] [ABSTRACT FROM AUTHOR]

Skeletal muscle is a pro-regenerative tissue, that utilizes a tissue-resident stem cell system to effect repair upon injury. Despite the demonstrated efficiency of this system in restoring muscle mass after many acute injuries, in conditions of severe trauma such as those evident in volumetric muscle loss (VML) (>20 % by mass), this self-repair capability is unable to restore tissue architecture, requiring interventions which currently are largely surgical. As a possible alternative, the generation of artificial muscle using tissue engineering approaches may also be of importance in the treatment of VML and muscle diseases such as dystrophies. Three-dimensional (3D) bioprinting has been identified as a promising technique for regeneration of the complex architecture of skeletal muscle. This review discusses existing treatment strategies following muscle damage, recent progress in bioprinting techniques, the bioinks used for muscle regeneration, the immunogenicity of scaffold materials, and in vitro and in vivo maturation techniques for 3D bio-printed muscle constructs. The pros and cons of these bioink formulations are also highlighted. Finally, we present the current limitations and challenges in the field and critical factors to consider for bioprinting approaches to become more translationa and to produce clinically relevant engineered muscle. This review discusses the physiopathology of muscle injuries and existing clinical treatment strategies for muscle damage, the types of bioprinting techniques that have been applied to bioprinting of muscle, and the bioinks commonly used for muscle regeneration. The pros and cons of these bioinks are highlighted. We present a discussion of existing gaps in the literature and critical factors to consider for the translation of bioprinting approaches and to produce clinically relevant engineered muscle. Finally, we provide insights into what we believe will be the next steps required before the realization of the application of tissue-engineered muscle in humans. We believe this manuscript is an insightful, timely, and instructive review that will guide future muscle bioprinting research from a fundamental construct creation approach, down a translational pathway to achieve the desired impact in the clinic. [Display omitted] [ABSTRACT FROM AUTHOR]

Diabetic wound management remains a significant challenge in clinical care due to bacterial infections, excessive inflammation, presence of excessive reactive oxygen species (ROS), and impaired angiogenesis. The use of multifunctional wound dressings has several advantages in diabetic wound healing. Moreover, the balance of macrophage polarization plays a crucial role in promoting skin regeneration. However, few studies have focused on the development of multifunctional wound dressings that can regulate the inflammatory microenvironment and promote diabetic wound healing. In this study, an extracellular matrix-inspired glycopeptide hydrogel composed of glucomannan and polypeptide was proposed for regulating the local microenvironment of diabetic wound sites. The hydrogel network, which was formed via Schiff base and hydrogen bonding interactions, effectively inhibited inflammation and promoted angiogenesis during wound healing. The hydrogels exhibited sufficient self-healing ability and had the potential to scavenge ROS and to activate the mannose receptor (MR), thereby inducing macrophage polarization toward the M2 phenotype. The experimental results confirm that the glycopeptide hydrogel is an effective tool for managing diabetic wounds by showing antibacterial, ROS scavenging, and anti-inflammatory effects, and promoting angiogenesis to facilitate wound repair and skin regeneration in vivo. •The designed wound dressing combines the advantage of natural polysaccharide and polypeptide. •The hydrogel promotes M2-polarized macrophages, antibacterial, scavenges ROS, and angiogenesis. •The multifunctional glycopeptide hydrogel dressing could accelerating diabetic wound healing in vivo. [Display omitted] [ABSTRACT FROM AUTHOR]

Kidney regeneration is hindered by the limited pool of intrinsic reparative cells. Advanced therapies targeting renal regeneration have the potential to alleviate the clinical and financial burdens associated with kidney disease. Delivery systems for cells, extracellular vesicles, or growth factors aimed at enhancing regeneration can benefit from vehicles enabling targeted delivery and controlled release. Hydrogels, optimized to carry biological cargo while promoting regeneration, have emerged as promising candidates for this purpose. This study aims to develop a hydrogel from decellularized kidney extracellular matrix (DKECM) and explore its biocompatibility as a biomaterial for renal regeneration. The resulting hydrogel crosslinks with temperature and exhibits a high concentration of extracellular matrix. The decellularization process efficiently removes detergent residues, yielding a pathogen-free biomaterial that is non-hemolytic and devoid of α-gal epitope. Upon interaction with macrophages, the hydrogel induces differentiation into both pro-inflammatory and anti-inflammatory phenotypes, suggesting an adequate balance to promote biomaterial functionality in vivo. Renal progenitor cells encapsulated in the DKECM hydrogel demonstrate higher viability and proliferation than in commercial collagen-I hydrogels, while also expressing tubular cells and podocyte markers in long-term culture. Overall, the injectable biomaterial derived from porcine DKECM is anticipated to elicit minimal host reaction while fostering progenitor cell bioactivity, offering a potential avenue for enhancing renal regeneration in clinical settings. The quest to improve treatments for kidney disease is crucial, given the challenges faced by patients on dialysis or waiting for transplants. Exciting new therapies combining biomaterials with cells can revolutionize kidney repair. In this study, researchers created a hydrogel from pig kidney. This gel could be used to deliver cells and other substances that help in kidney regeneration. Despite coming from pigs, it's safe for use in humans, with no harmful substances and reduced risk of immune reactions. Importantly, it promotes a balanced healing response in the body. This research not only advances our knowledge of kidney repair but also offers hope for more effective treatments for kidney diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

Communication between tumors and lymph nodes carries substantial significance for antitumor immunotherapy. Remodeling the immune microenvironment of tumor-draining lymph nodes (TdLN) plays a key role in enhancing the anti-tumor ability of immunotherapy. In this study, we constructed a biomimetic artificial lymph node structure composed of F127 hydrogel loading effector memory T (T EM) cells and PD-1 inhibitors (aPD-1). The biomimetic lymph nodes facilitate the delivery of T EM cells and aPD-1 to the TdLN and the tumor immune microenvironment, thus realizing effective and sustained anti-tumor immunotherapy. Exploiting their unique gel-forming and degradation properties, the cold tumors were speedily transformed into hot tumors via T EM cell supplementation. Meanwhile, the efficacy of aPD-1 was markedly elevated compared with conventional drug delivery methods. Our finding suggested that the development of F127@T EM @aPD-1 holds promising potential as a future novel clinical drug delivery technique. F127@T EM @aPD-1 show unique advantages in cancer treatment. When injected subcutaneously, F127@T EM @aPD-1 can continuously supplement T EM cells and aPD-1 to tumor draining lymph nodes (TdLN) and the tumor microenvironment, not only improving the efficacy of ICB therapy through slow release, but also exhibiting dual regulatory effects on the tumor and TdLN. [Display omitted] [ABSTRACT FROM AUTHOR]

Low back pain is a leading cause of disability worldwide, often attributed to intervertebral disc (IVD) degeneration with loss of the functional nucleus pulposus (NP). Regenerative strategies utilizing biomaterials and stem cells are promising for NP repair. Human NP tissue is highly viscoelastic, relaxing stress rapidly under deformation. However, the impact of tissue-specific viscoelasticity on the activities of adipose-derived stem cells (ASC) remains largely unexplored. Here, we investigated the role of matrix viscoelasticity in regulating ASC differentiation for IVD regeneration. Viscoelastic alginate hydrogels with stress relaxation time scales ranging from 100 s to 1000s were developed and used to culture human ASCs for 21 days. Our results demonstrated that the fast-relaxing hydrogel significantly enhanced ASCs long-term cell survival and NP-like extracellular matrix secretion of aggrecan and type-II collagen. Moreover, gene expression analysis revealed a substantial upregulation of the mechanosensitive ion channel marker TRPV4 and NP-specific markers such as SOX9, HIF-1α, KRT18, CDH2 and CD24 in ASCs cultured within the fast-relaxing hydrogel, compared to slower-relaxing hydrogels. These findings highlight the critical role of matrix viscoelasticity in regulating ASC behavior and suggest that viscoelasticity is a key parameter for novel biomaterials design to improve the efficacy of stem cell therapy for IVD regeneration. Systematically characterized the influence of tissue-mimetic viscoelasticity on ASC. NP-mimetic hydrogels with tunable viscoelasticity and tissue-matched stiffness. Long-term survival and metabolic activity of ASCs are substantially improved in the fast-relaxing hydrogel. The fast-relaxing hydrogel allows higher rate of cell protrusions formation and matrix remodeling. ASC differentiation towards an NP-like cell phenotype is promoted in the fast-relaxing hydrogel, with more CD24 positive expression indicating NP committed cell fate. The expression of TRPV4 , a molecular sensor of matrix viscoelasticity, is significantly enhanced in the fast-relaxing hydrogel, indicating ASC sensing matrix viscoelasticity during cell development. The NP-specific ECM secretion of ASC is considerably influenced by matrix viscoelasticity, where the deposition of aggrecan and type-II collagen are significantly enhanced in the fast-relaxing hydrogel. [Display omitted] [ABSTRACT FROM AUTHOR]

While it is known that cells with differential adhesion tend to segregate and preferentially sort, the physical forces governing sorting and invasion in heterogeneous tumors remain poorly understood. To investigate this, we tune matrix confinement, mimicking changes in the stiffness and confinement of the tumor microenvironment, to explore how physical confinement influences individual and collective cell migration in 3D spheroids. High levels of confinement lead to cell sorting while reducing matrix confinement triggers the collective fluidization of cell motion. Cell sorting, which depends on cell-cell adhesion, is crucial to this phenomenon. Burst-like migration does not occur for spheroids that have not undergone sorting, regardless of the degree of matrix confinement. Using computational Self-Propelled Voronoi modeling, we show that spheroid sorting and invasion into the matrix depend on the balance between cell-generated forces and matrix resistance. The findings support a model where matrix confinement modulates 3D spheroid sorting and unjamming in an adhesion-dependent manner, providing insights into the mechanisms of cell sorting and migration in the primary tumor and toward distant metastatic sites. The mechanical properties of the tumor microenvironment significantly influence cancer cell migration within the primary tumor, yet how these properties affect intercellular interactions in heterogeneous tumors is not well understood. By utilizing calcium and calcium chelators, we dynamically alter collagen-alginate hydrogel stiffness and investigate tumor cell behavior within co-culture spheroids in response to varying degrees of matrix confinement. High confinement is found to trigger cell sorting while reducing confinement for sorted spheroids facilitates collective cell invasion. Notably, without prior sorting, spheroids do not exhibit burst-like migration, regardless of confinement levels. This work establishes that matrix confinement and intercellular adhesion regulate 3D spheroid dynamics, offering insights into cellular organization and migration within the primary tumor. [Display omitted] [ABSTRACT FROM AUTHOR]

Oral ulcers can significantly reduce the life quality of patients and even lead to malignant transformations. Local treatments using topical agents are often ineffective because of the wet and dynamic environment of the oral cavity. Current clinical treatments for oral ulcers, such as corticosteroids, have limitations and side effects for long-term usage. Here, we develop adhesive hydrogel patches (AHPs) that effectively promote the healing of oral ulcers in a rat model. The AHPs are comprised of the quaternary ammonium salt of chitosan, aldehyde-functionalized hyaluronic acid, and a tridentate complex of protocatechualdehyde and Fe3+ (PF). The AHPs exhibit tunable mechanical properties, self-healing ability, and wet adhesion on the oral mucosa. Through controlling the formula of the AHPs, PF released from the AHPs in a temporal manner. We further show that the AHPs have good biocompatibility and the capability to heal oral ulcers rapidly. Both in vitro and in vivo experiments indicate that the PF released from AHPs facilitated ulcer healing by suppressing inflammation, promoting macrophage polarization, enhancing cell proliferation, and inducing epithelial-mesenchymal transition involving inflammation, proliferation, and maturation stages. This study provides insights into the healing of oral ulcers and presents an effective therapeutic biomaterial for the treatment of oral ulcers. By addressing the challenges associated with current clinical treatments for oral ulcers, the development of adhesive hydrogel patches (AHPs) presents an effective approach. These AHPs possess unique properties, such as tunable mechanical characteristics, self-healing ability, and strong adhesion to the mucosa. Through controlled release of protocatechualdehyde-Fe3+ complex, the AHPs facilitate the healing process by suppressing inflammation, promoting cell proliferation, and inducing epithelial-mesenchymal transition. The study not only provides valuable insights into the healing mechanisms of oral ulcers but also introduces a promising therapeutic biomaterial. This work holds significant scientific interest and demonstrates the potential to greatly improve the treatment outcomes and quality of life for individuals suffering from oral ulcers. [Display omitted] [ABSTRACT FROM AUTHOR]

Wound infection commonly causes delayed healing, especially in the setting of chronic wounds. Local release of antibiotics is considered a viable approach to treat chronic wounds. We have developed a versatile telodendrimer (TD) platform for efficient loading of charged antibiotic molecules via a combination of multivalent and synergistic charge and hydrophobic interactions. The conjugation of TD in biocompatible hydrogel allows for topical application to provide sustained antibiotic release. Notably, a drug loading capacity as high as 20 % of the drug-to-resin dry weight ratio can be achieved. The payload content (PC) and release profile of the various antibiotics can be optimized by fine-tuning TD density and valency in hydrogel based on the charge and hydrophobic features of the drug, e.g. , polymyxin B (PMB), gentamycin (GM), and daptomycin (Dap), for effective infection control. We have shown that hydrogel with moderately reduced TD density demonstrates a more favorable release profile than hydrogel with higher TD density. Antibiotics loaded in TD hydrogel have comparable antimicrobial potency and reduced cytotoxicity compared to the free antibiotics due to a prolonged, controlled drug release profile. In a mouse model of skin and soft tissue infection, the subcutaneous administration of PMB-loaded TD hydrogel effectively eliminated the bacterial burden. Overall, these results suggest that engineerable TD hydrogels have great potential as a topical treatment to control infection for wound healing. Wound infection causes a significant delay in the wound healing process, which results in a significant financial and resource burden to the healthcare system. PEGA-telodendrimer (TD) resin hydrogel is an innovative and versatile platform that can be fine-tuned to efficiently encapsulate different antibiotics by altering charged and hydrophobic structural moieties. Additionally, this platform is advantageous as the TD density in the resin can also be fine-tuned to provide the desired antibiotic payload release profile. Sustained antibiotics release through optimization of TD density provides a prolonged therapeutic window and reduces burst release-induced cytotoxicity compared to conventional antibiotics application. Studies in a preclinical mouse model of bacteria-induced skin and soft tissue infection demonstrated promising therapeutic efficacy as evidenced by effective infection control and prolonged antibacterial efficacy of antibiotics-loaded PEGA-TD resin. In conclusion, the PEGA-TD resin platform provides a highly customizable approach for effective antibiotics release with significant potential for topical application to treat various bacterial wound infections to promote wound healing. [Display omitted] [ABSTRACT FROM AUTHOR]

Annulus fibrosus (AF) defect is an important cause of disc re-herniation after discectomy. The self-regeneration ability of the AF is limited, and AF repair is always hindered by the inflammatory microenvironment after injury. Hydrogels represent one of the most promising materials for AF tissue engineering strategies. However, currently available commercial hydrogels cannot withstand the harsh mechanical load within intervertebral disc. In the present study, an innovative triple cross-linked oxidized hyaluronic acid (OHA)-dopamine (DA)- polyacrylamide (PAM) composite hydrogel, modified with collagen mimetic peptide (CMP) and supplied with transforming growth factor beta 1 (TGF-β1) (OHA-DA-PAM/CMP/TGF-β1 hydrogel) was developed for AF regeneration. The hydrogel exhibited robust mechanical strength, strong bioadhesion, and significant self-healing capabilities. Modified with collagen mimetic peptide, the hydrogel exhibited extracellular-matrix-mimicking properties and sustained the AF cell phenotype. The sustained release of TGF-β1 from the hydrogel was pivotal in recruiting AF cells and promoting extracellular matrix production. Furthermore, the composite hydrogel attenuated LPS-induced inflammatory response and promote ECM synthesis in AF cells via suppressing NFκB/NLRP3 pathway. In vivo , the composite hydrogel successfully sealed AF defects and alleviated intervertebral disk degeneration in a rat tail AF defect model. Histological evaluation showed that the hydrogel integrated well with host tissue and facilitated AF repair. The strategy of recruiting endogenous cells and providing an extracellular-matrix-mimicking and anti-inflammatory microenvironment using the mechanically tough composite OHA-DA-PAM/CMP/TGF-β1 hydrogel may be applicable for AF defect repair in the clinic. Annulus fibrosus (AF) repair is challenging due to its limited self-regenerative capacity and post-injury inflammation. In this study, a mechanically tough and highly bioadhesive triple cross-linked composite hydrogel, modified with collagen mimetic peptide (CMP) and supplemented with transforming growth factor beta 1 (TGF-β1), was developed to facilitate AF regeneration. The sustained release of TGF-β1 enhanced AF cell recruitment, while both TGF-β1 and CMP could modulate the microenvironment to promote AF cell proliferation and ECM synthesis. In vivo , this composite hydrogel effectively promoted the AF repair and mitigated the intervertebral disc degeneration. This research indicates the clinical potential of the OHA-DA-PAM/CMP/TGF-β1 composite hydrogel for repairing AF defects. [Display omitted] [ABSTRACT FROM AUTHOR]

Designing proteins that fold and assemble over different length scales provides a way to tailor the mechanical properties and biological performance of hydrogels. In this study, we designed modular proteins that self-assemble into fibrillar networks and, as a result, form hydrogel materials with novel properties. We incorporated distinct functionalities by connecting separate self-assembling (A block) and cell-binding (B block) domains into single macromolecules. The number of self-assembling domains affects the rigidity of the fibers and the final storage modulus G′ of the materials. The mechanical properties of the hydrogels could be tuned over a broad range (G′ = 0.1 – 10 kPa), making them suitable for the cultivation and differentiation of multiple cell types, including cortical neurons and human mesenchymal stem cells. Moreover, we confirmed the bioavailability of cell attachment domains in the hydrogels that can be further tailored for specific cell types or other biological applications. Finally, we demonstrate the versatility of the designed proteins for application in biofabrication as 3D scaffolds that support cell growth and guide their function. Designed proteins that enable the decoupling of biophysical and biochemical properties within the final material could enable modular biomaterial engineering. In this context, we present a designed modular protein platform that integrates self-assembling domains (A blocks) and cell-binding domains (B blocks) within a single biopolymer. The linking of assembly domains and cell-binding domains this way provided independent tuning of mechanical properties and inclusion of biofunctional domains. We demonstrate the use of this platform for biofabrication, including neural cell culture and 3D printing of scaffolds for mesenchymal stem cell culture and differentiation. Overall, this work highlights how informed design of biopolymer sequences can enable the modular design of protein-based hydrogels with independently tunable biophysical and biochemical properties. [Display omitted] [ABSTRACT FROM AUTHOR]

The tumor microenvironment (TME) in pancreatic adenocarcinoma (PDAC) is a complex milieu of cellular and non-cellular components. Pancreatic cancer cells (PCC) and cancer-associated fibroblasts (CAF) are two major cell types in PDAC TME, whereas the non-cellular components are enriched with extracellular matrices (ECM) that contribute to high stiffness and fast stress-relaxation. Previous studies have suggested that higher matrix rigidity promoted aggressive phenotypes of tumors, including PDAC. However, the effects of dynamic viscoelastic matrix properties on cancer cell fate remain largely unexplored. The focus of this work was to understand the effects of such dynamic matrix properties on PDAC cell behaviors, particularly in the context of PCC/CAF co-culture. To this end, we engineered gelatin-norbornene (GelNB) based hydrogels with a built-in mechanism for simultaneously increasing matrix elastic modulus and viscoelasticity. Two GelNB-based macromers, namely GelNB-hydroxyphenylacetic acid (GelNB-HPA) and GelNB-boronic acid (GelNB-BA), were modularly mixed and crosslinked with 4-arm poly(ethylene glycol)-thiol (PEG4SH) to form elastic hydrogels. Treating the hybrid hydrogels with tyrosinase not only increased the elastic moduli of the gels (due to HPA dimerization) but also concurrently produced 1,2-diols that formed reversible boronic acid-diol bonding with the BA groups on GelNB-BA. We employed patient-derived CAF and a PCC cell line COLO-357 to demonstrate the effect of increasing matrix stiffness and viscoelasticity on CAF and PCC cell fate. Our results indicated that in the stiffened environment, PCC underwent epithelial-mesenchymal transition. In the co-culture PCC and CAF spheroid, CAF enhanced PCC spreading and stimulated collagen 1 production. Through mRNA-sequencing, we further showed that stiffened matrices, regardless of the degree of stress-relaxation, heightened the malignant phenotype of PDAC cells. The pancreatic cancer microenvironment is a complex milieu composed of various cell types and extracellular matrices. It has been suggested that stiffer matrices could promote aggressive behavior in pancreatic cancer, but the effect of dynamic stiffening and matrix stress-relaxation on cancer cell fate remains largely undefined. This study aimed to explore the impact of dynamic changes in matrix viscoelasticity on pancreatic ductal adenocarcinoma (PDAC) cell behavior by developing a hydrogel system capable of simultaneously increasing stiffness and stress-relaxation on demand. This is achieved by crosslinking two gelatin-based macromers through orthogonal thiol-norbornene photochemistry and post-gelation stiffening with mushroom tyrosinase. The results revealed that higher matrix stiffness, regardless of the degree of stress relaxation, exacerbated the malignant characteristics of PDAC cells. [Display omitted] [ABSTRACT FROM AUTHOR]

Intrauterine adhesions (IUA) are the most common cause of uterine infertility, and conventional treatments have not consistently achieved satisfactory pregnancy rates. Stem cell therapy shows promising potential for the clinical treatment of IUA. Although various advanced biomaterials have been designed for delivering stem cells to the uterine cavity, there remain significant challenges, particularly in devising therapeutic strategies for clinical application that minimize surgical incisions and conform to the intricate structure of uterine cavity. Herein, an injectable hydrogel loaded with human umbilical cord-derived mesenchymal stem cells (UCMSCs) was synthesized via the Diels-Alder click reaction for endometrial regeneration and fertility restoration, exhibiting suitable mechanical properties, good biocompatibility, and desirable degradation properties. Notably, this hydrogel permitted minimally invasive administration and integrated seamlessly with surrounding tissue. Our study revealed that the UCMSCs-laden injectable hydrogel enhanced cell proliferation, migration, angiogenesis, and exhibited anti-fibrotic effects in vitro. The implantation of this hydrogel significantly facilitated endometrium regeneration and restored fertility in a rat endometrial damage model. Mechanistically, in vivo results indicated that the UCMSCs-laden injectable hydrogel effectively promoted macrophage recruitment and facilitated M2 phenotype polarization. Collectively, this hydrogel demonstrated efficacy in regenerating damaged endometrium, leading to the restoration of fertility. Consequently, it holds promise as a potential therapeutic strategy for endometrial damage and fertility decline arising from intrauterine adhesions. Severe endometrial traumas frequently lead to intrauterine adhesions and subsequent infertility. Stem cell therapy shows promising potential for the clinical treatment of IUA; however, challenges remain, including low delivery efficiency and compromised stem cell activity during the delivery process. In this study, we fabricated an injectable hydrogel loaded with UCMSCs via the Diels-Alder click reaction, which exhibited unique bioorthogonality. The in situ-gelling hydrogels could be introduced through a minimally invasive procedure and adapt to the intricate anatomy of the uterus. The UCMSCs-laden injectable hydrogel promoted endometrial regeneration and fertility restoration in a rat endometrial damage model, efficaciously augmenting macrophage recruitment and promoting their polarization to the M2 phenotype. The administration of UCMSCs-laden injectable hydrogel presents a promising therapeutic strategy for patients with severe intrauterine adhesion. [Display omitted] [ABSTRACT FROM AUTHOR]

The existing strategies for myocardial infarction therapy mainly focus on reinstating myocardial blood supply, often disregarding the intrinsic and intricate microenvironment created by elevated levels of reactive oxygen species (ROS) that accompanies myocardial infarction. This microenvironment entails cardiomyocytes apoptosis, substantial vascular cell death, excessive inflammatory infiltration and fibrosis. In such situation, the present study introduces a zinc-based nanozyme injectable multifunctional hydrogel, crafted from ZIF-8, to counteract ROS effects after myocardial infarction. The hydrogel exhibits both superoxide dismutase (SOD)-like and catalase (CAT)-like enzymatic activities, proficiently eliminating surplus ROS in the infarcted region and interrupting ROS-driven inflammatory cascades. Furthermore, the hydrogel's exceptional immunomodulatory ability spurs a notable transformation of macrophages into the M2 phenotype, effectively neutralizing inflammatory factors and indirectly fostering vascularization in the infarcted region. For high ROS and demanding for zinc of the infarcted microenvironment, the gradual release of zinc ions as the hydrogel degrades further enhances the bioactive and catalytic performance of the nanozymes, synergistically promoting cardiac function post myocardial infarction. In conclusion, this system of deploying catalytic nanomaterials within bioactive matrices for ROS-related ailment therapy not only establishes a robust foundation for biomedical material development, but also promises a holistic approach towards addressing myocardial infarction complexities. Myocardial infarction remains the leading cause of death worldwide. However, the existing strategies for myocardial infarction therapy mainly focus on reinstating myocardial blood supply. These therapies often ignore the intrinsic and intricate microenvironment created by elevated levels of reactive oxygen species (ROS). Hence, we designed an injectable Zn-Based nanozyme hydrogel with ROS scavenging activity for myocardial infarction therapy. ALG-(ZIF-8) can significantly reduce ROS in the infarcted area and alleviate the ensuing pathological process. ALG-(ZIF-8) gradually releases zinc ions to participate in the repair process and improves cardiac function. Overall, this multifunctional hydrogel equipped with ZIF-8 makes full use of the characteristics of clearing ROS and slowly releasing zinc ions, and we are the first to test the therapeutic efficacy of Zinc-MOFs crosslinked-alginate hydrogel for myocardial infarction. [Display omitted] [ABSTRACT FROM AUTHOR]

The combination of hydrogels and magnetic nanoparticles, scarcely explored to date, offers a wide range of possibilities for innovative therapies. Herein, we have designed hybrid 3D matrices integrating natural polymers, such as collagen, chitosan (CHI) and hyaluronic acid (HA), to provide soft and flexible 3D networks mimicking the extracellular matrix of natural tissues, and iron oxide nanoparticles (IONPs) that deliver localized heat when exposed to an alternating magnetic field (AMF). First, colloidally stable nanoparticles with a hydrodynamic radius of ∼20 nm were synthesized and coated with either CHI (NPCHI) or HA (NPHA). Then, collagen hydrogels were homogeneously loaded with these coated-IONPs resulting in soft (E 0 ∼ 2.6 kPa), biodegradable and magnetically responsive matrices. Polymer-coated IONPs in suspension preserved primary neural cell viability and neural differentiation even at the highest dose (0.1 mg Fe/mL), regardless of the coating, even boosting neuronal interconnectivity at lower doses. Magnetic hydrogels maintained high neural cell viability and sustained the formation of highly interconnected and differentiated neuronal networks. Interestingly, those hydrogels loaded with the highest dose of NPHA (0.25 mgFe/mg polymer) significantly impaired non-neuronal differentiation with respect to those with NPCHI. When evaluated under AMF, cell viability slightly diminished in comparison with control hydrogels magnetically stimulated, but not compared to their counterparts without stimulation. Neuronal differentiation under AMF was only affected on collagen hydrogels with the highest dose of NPHA, while non-neuronal differentiation regained control values. Taken together, NPCHI-loaded hydrogels displayed a superior performance, maybe benefited from their higher nanomechanical fluidity. Hydrogels and magnetic nanoparticles are undoubtedly useful biomaterials for biomedical applications. Nonetheless, the combination of both has been scarcely explored to date. In this study, we have designed hybrid 3D matrices integrating both components as promising magnetically responsive platforms for neural therapeutics. The resulting collagen scaffolds were soft (E 0 ∼ 2.6 kPa) and biodegradable hydrogels with capacity to respond to external magnetic stimuli. Primary neural cells proved to grow on these substrates, preserving high viability and neuronal differentiation percentages even under the application of a high-frequency alternating magnetic field. Importantly, those hydrogels loaded with chitosan-coated iron oxide nanoparticles displayed a superior performance, likely related to their higher nanomechanical fluidity. [Display omitted] [ABSTRACT FROM AUTHOR]

Chronic diabetic wounds are a severe complication of diabetes, often leading to high treatment costs and high amputation rates. Numerous studies have revealed that nitric oxide (NO) therapy is a promising option because it favours wound revascularization. Here, base-paired injectable adhesive hydrogels (CAT) were prepared using adenine- and thymine-modified chitosan (CSA and CST). By further introducing S-nitrosoglutathione (GSNO) and binary l -arginine (bArg), we obtained a NO sustained-release hydrogel (CAT/bArg/GSON) that was more suitable for the treatment of chronic wounds. The results showed that the expression of HIF-1α and VEGF was upregulated in the CAT/bArg/GSON group, and improved blood vessel regeneration was observed, indicating an important role of NO. In addition, the research findings revealed that following treatment with the CAT/bArg/GSON hydrogel, the viability of Staphylococcus aureus and Escherichia coli decreased to 14 ± 2 % and 6 ± 1 %, respectively. Moreover, the wound microenvironment was improved, as evidenced by a 60 ± 1 % clearance of DPPH. In particular, histological examination and immunohistochemical staining results showed that wounds treated with CAT/bArg/GSNO exhibited denser neovascularization, faster epithelial tissue regeneration, and thicker collagen deposition. Overall, this study proposes an effective strategy to prepare injectable hydrogel dressings with dual NO donors. The functionality of CAT/bArg/GSON has been thoroughly demonstrated in research on chronic wound vascular regeneration, indicating that CAT/bArg/GSON could be a potential option for promoting chronic wound healing. This article prepares a chitosan hydrogel utilizing the principle of complementary base pairing, which offers several advantages, including good adhesion, biocompatibility, and flow properties, making it a good material for wound dressings. Loaded GSNO and bArg can steadily release NO and l -arginine through the degradation of the gel. Then, the released l -arginine not only possesses antioxidant properties but can also continue to generate a small amount of NO under the action of NOS. This design achieves a sustained and stable supply of NO at the wound site, maximizing the angiogenesis-promoting and antibacterial effects of NO. More neovascularization and abundant collagen were observed in the regenerated tissues. This study provides an effective repair hydrogel material for diabetic wound. [Display omitted] [ABSTRACT FROM AUTHOR]

Epidural steroid injection (ESI) is a common therapeutic approach for managing sciatica caused by lumbar disc herniation (LDH). However, the short duration of therapeutic efficacy and the need for repeated injections pose challenges in LDH treatment. The development of a controlled delivery system capable of prolonging the effectiveness of ESI and reducing the frequency of injections, is highly significant in LDH clinical practice. In this study, we utilized a thiol-ene click chemistry to create a series of injectable hyaluronic acid (HA) based release systems loaded with diphasic betamethasone, including betamethasone dipropionate (BD) and betamethasone 21-phosphate disodium (BP) (BD/BP@HA). BD/BP@HA hydrogel implants demonstrated biocompatibility and biodegradability to matched neuronal tissues, avoiding artificial compression following injection. The sustained release of betamethasone from BD/BP@HA hydrogels effectively inhibited both acute and chronic neuroinflammation by suppressing the nuclear factor kappa-B (NF-κB) pathway. In a mouse model of LDH, the epidural administration of BD/BP@HA efficiently alleviated LDH-induced sciatica for at least 10 days by inhibiting the activation of macrophages and microglia in dorsal root ganglion and spinal dorsal horn, respectively. The newly developed HA hydrogels represent a valuable platform for achieving sustained drug release. Additionally, we provide a simple paradigm for fabricating BD/BP@HA for epidural injection, demonstrating greater and sustained efficiency in alleviating LDH-induced sciatica compared to traditional ESI and displaying potentials for clinical translation. This system has the potential to revolutionize drug delivery for co-delivery of both soluble and insoluble drugs, thereby making a significant impact in the pharmaceutical industry. Lumbar disc herniation (LDH) is a common degenerative disorder leading to sciatica and spine surgery. Although epidural steroid injection (ESI) is routinely used to alleviate sciatica, the efficacy is short and repeated injections are required. There remains challenging to prolong the efficacy of ESI. Herein, an injectable hyaluronic acid (HA) hydrogel implant by crosslinking acrylated-modified HA (HA-A) with thiol-modified HA (HA-SH) was designed to achieve a biphasic release of betamethasone. The hydrogel showed biocompatibility and biodegradability to match neuronal tissues. Notably, compared to traditional ESI, the hydrogel better alleviated sciatica in vivo by synergistically inhibiting the neuroinflammation in central and peripheral nervous systems. We anticipate the injectable HA hydrogel implant has the potential for clinical translation in treating LDH-induced sciatica. [Display omitted] [ABSTRACT FROM AUTHOR]

Low back pain resulting from disc degeneration is a leading cause of disability worldwide. However, to date few therapies target the cause and fail to repair the intervertebral disc (IVD). This study investigates the ability of an injectable hydrogel (NPgel), to inhibit catabolic protein expression and promote matrix expression in human nucleus pulposus (NP) cells within a tissue explant culture model isolated from degenerate discs. Furthermore, the injection capacity of NPgel into naturally degenerate whole human discs, effects on mechanical function, and resistance to extrusion during loading were investigated. Finally, the induction of potential regenerative effects in a physiologically loaded human organ culture system was investigated following injection of NPgel with or without bone marrow progenitor cells. Injection of NPgel into naturally degenerate human IVDs increased disc height and Young's modulus, and was retained during extrusion testing. Injection into cadaveric discs followed by culture under physiological loading increased MRI signal intensity, restored natural biomechanical properties and showed evidence of increased anabolism and decreased catabolism with tissue integration observed. These results provide essential proof of concept data supporting the use of NPgel as an injectable therapy for disc regeneration. Low back pain resulting from disc degeneration is a leading cause of disability worldwide. However, to date few therapies target the cause and fail to repair the intervertebral disc. This study investigated the potential regenerative properties of an injectable hydrogel system (NPgel) within human tissue samples. To mimic the human in vivo conditions and the unique IVD niche, a dynamically loaded intact human disc culture system was utilised. NPgel improved the biomechanical properties, increased MRI intensity and decreased degree of degeneration. Furthermore, NPgel induced matrix production and decreased catabolic factors by the native cells of the disc. This manuscript provides evidence for the potential use of NPgel as a regenerative biomaterial for intervertebral disc degeneration. [Display omitted] [ABSTRACT FROM AUTHOR]

Dry eye disease (DED) is currently the most prevalent condition seen in ophthalmology outpatient clinics, representing a significant public health issue. The onset and progression of DED are closely associated with oxidative stress-induced inflammation and damage. To address this, an aldehyde-functionalized F127 (AF127) hydrogel eye drop delivering multifunctional antioxidant Cu 2−x Se nanoparticles (Cu 2−x Se NPs) was designed. The research findings revealed that the Cu 2−x Se nanoparticles exhibit unexpected capabilities in acting as superoxide dismutase and glutathione peroxidase. Additionally, Cu 2−x Se NPs possess remarkable efficacy in scavenging reactive oxygen species (ROS) and mitigating oxidative damage. Cu 2−x Se NPs displayed promising therapeutic effects in a mouse model of dry eye. Detailed investigation revealed that the nanoparticles exert antioxidant, anti-apoptotic, and inflammation-mitigating effects by modulating the NRF2 and p38 MAPK signalling pathways. The AF127 hydrogel eye drops exhibit good adherence to the ocular surface through the formation of Schiff-base bonds. These findings suggest that incorporating antioxidant Cu 2−x Se nanoparticles into a tissue-adhesive hydrogel could present a highly effective therapeutic strategy for treating dry eye disease and other disorders associated with reactive oxygen species. A new formulation for therapeutic eye drops to be used in the treatment of dry eye disease (DED) was developed. The formulation combines copper-selenium nanoparticles (Cu 2-x Se NPs) with aldehyde-functionalized Pluronic F127 (AF127). This is the first study to directly examine the effects of Cu 2-x Se NPs in ophthalmology. The NPs exhibited antioxidant capabilities and enzyme-like properties. They effectively eliminated reactive oxygen species (ROS) and inhibited apoptosis through the NRF2 and p38 MAPK signalling pathways. Additionally, the AF127 hydrogel enhanced tissue adhesion by forming Schiff-base links. In mouse model of DED, the Cu 2-x Se NPs@AF127 eye drops demonstrated remarkable efficacy in alleviating symptoms of DED. These findings indicate the potential of Cu 2-x Se NPs as a readily available and user-friendly medication for the management of DED. [Display omitted] [ABSTRACT FROM AUTHOR]

The periodontal ligament (PDL) is a distinctive yet critical connective tissue vital for maintaining the integrity and functionality of tooth-supporting structures. However, PDL repair poses significant challenges due to the complexity of its mechanical microenvironment encompassing hard-soft-hard tissues, with the viscoelastic properties of the PDL being of particular interest. This review delves into the significant role of viscoelastic hydrogels in PDL regeneration, underscoring their utility in simulating biomimetic three-dimensional microenvironments. We review the intricate relationship between PDL and viscoelastic mechanical properties, emphasizing the role of tissue viscoelasticity in maintaining mechanical functionality. Moreover, we summarize the techniques for characterizing PDL's viscoelastic behavior. From a chemical bonding perspective, we explore various crosslinking methods and characteristics of viscoelastic hydrogels, along with engineering strategies to construct viscoelastic cell microenvironments. We present a detailed analysis of the influence of the viscoelastic microenvironment on cellular mechanobiological behavior and fate. Furthermore, we review the applications of diverse viscoelastic hydrogels in PDL repair and address current challenges in the field of viscoelastic tissue repair. Lastly, we propose future directions for the development of innovative hydrogels that will facilitate not only PDL but also systemic ligament tissue repair. • An overview of the construction and application of viscoelastic hydrogels in periodontal ligament repair and regeneration from a materials perspective. • The first summary of the methods and results of measuring the viscoelasticity of the periodontal ligament. • Viscoelastic materials have the potential for periodontal ligaments bionic repair. [Display omitted] [ABSTRACT FROM AUTHOR]

Fibrillar collagens and glycosaminoglycans (GAGs) are structural biomolecules that are natively abundant to the extracellular matrix (ECM). Prior studies have quantified the effects of GAGs on the bulk mechanical properties of the ECM. However, there remains a lack of experimental studies on how GAGs alter other biophysical properties of the ECM, including ones that operate at the length scales of individual cells such as mass transport efficiency and matrix microstructure. This study focuses on the GAG molecules chondroitin sulfate (CS), dermatan sulfate (DS), and hyaluronic acid (HA). CS and DS are stereoisomers while HA is the only non-sulfated GAG. We characterized and decoupled the effects of these GAG molecules on the stiffness, transport, and matrix microarchitecture properties of type I collagen hydrogels using mechanical indentation testing, microfluidics, and confocal reflectance imaging, respectively. We complement these biophysical measurements with turbidity assays to profile collagen aggregate formation. Surprisingly, only HA enhanced the ECM indentation modulus, while all three GAGs had no effect on hydraulic permeability. Strikingly, we show that CS, DS, and HA differentially regulate the matrix microarchitecture of hydrogels due to their alterations to the kinetics of collagen self-assembly. In addition to providing information on how GAGs define key physical properties of the ECM, this work shows new ways in which stiffness measurements, microfluidics, microscopy, and turbidity kinetics can be used complementarily to reveal details of collagen self-assembly and structure. Collagen and glycosaminoglycans (GAGs) are integral to the structure, function, and bioactivity of the extracellular matrix (ECM). Despite widespread interest in collagen-GAG composite hydrogels, there is a lack of quantitative understanding of how different GAGs alter the biophysical properties of the ECM across tissue, cellular, and subcellular length scales. Here we show using mechanical, microfluidic, microscopy, and analytical methods and measurements that the GAG molecules chondroitin sulfate, dermatan sulfate, and hyaluronic acid differentially regulate the mechanical, transport, and microstructural properties of hydrogels due to their alterations to the kinetics of collagen self-assembly. As such, these results will inform improved design and utilization of collagen-based scaffolds of tailored composition, mechanical properties, molecular availability due to mass transport, and microarchitecture. [Display omitted] [ABSTRACT FROM AUTHOR]

Inspired by the anisotropic structure of biological tissues, anisotropic hydrogels have been developed using various nanofillers, however, it remains a big challenge to synthesize hydrogels with large swelling anisotropy. Herein a single molecule filler, α-helical polypeptide, instead of nanoscale fillers, was used to synthesize anisotropic hydrogels. First nematic liquid crystal of poly(γ-benzyl l-glutamate) (PBLG) was prepared by shearing and stabilized by embedding in a crosslinked polymer matrix. The resulting PBLG composite gels were then converted to poly(L-glutamic acid) (PLGA) composite gels by debenzylation. The rigid rod-like structure of α-helical PBLG chains makes them easy to be orientated. The pH-sensitivity of PLGA makes the resulting composite gels pH-sensitive without the need to couple with a stimuli-responsive hydrogel matrix. In response to pH change PLGA composite gels swell anisotropically with a much larger swelling degree in the radial direction than in the axial direction. The swelling anisotropy (3.43) is much higher than most anisotropic hydrogels, particularly the stimuli-responsive ones reported previously. The composite gel also exhibits anisotropic mechanical properties with a larger Young's modulus in the axial direction than that in the radial direction. Preliminary test demonstrated that the composite gels have potential in embolotherapy thanks to its large pH-triggered anisotropic swelling. Anisotropic hydrogels have important biomedical applications. Introduction of oriented nanofillers has been demonstrated a popular and versatile method for their synthesis, however, it remains a big challenge to achieve large swelling anisotropy. Herein a single molecule filler, α-helical polypeptide, instead of nanoscale fillers, was used to synthesize anisotropic hydrogels. This filler can be easily oriented by shearing. More importantly, as single molecule filler, it can constrain the swelling of hydrogel matrix more effectively. Using this filler, a pH-sensitive hydrogel with large swelling anisotropy (3.43) was successfully synthesized. Thanks to its large pH-triggered anisotropic swelling the hydrogel was successfully used as embolic agent to occlude vessels. [Display omitted] [ABSTRACT FROM AUTHOR]

The management of chronic diabetic wounds is a complex issue that requires wound repair, regulation of inflammatory levels, and intervention to prevent bacterial infection. To address this issue, we developed a multifunctional photothermally responsive hydrogel (PAG-CuS) as an effective platform for managing the entire wound-healing process, including promoting wound healing, providing anti-inflammatory therapy, and performing photothermal sterilization. Constructed through copolymerization of acrylic acid (AA), methacrylic anhydride-modified gelatin (GelMA), and lipoic acid sodium (LAS) coated copper sulfide nanoparticles (CuS@LAS), PAG-CuS possessed a porous three-dimensional structure that promoted cell adhesion and had a substantial water-holding capacity. Additionally, the internal CuS@LAS not only conferred photothermal antibacterial properties to the hydrogel but also served as physical cross-linking agents, thus enhancing its mechanical strength. Under the NIR-induced photothermal effect, the porous hydrogel liberates CuS@LAS, and later CuS@LAS expels LAS via micelle deassembly to eliminate intracellular ROS. This results in the down-regulation of MMP-9 expression, promoting ECM production and facilitating wound healing. Meanwhile, the release of Cu2+ from PAG-CuS could enhance CD31 expression in endothelial cells, promoting microvessel formation, which is crucial for wound healing. In the diabetic wound model of GK rats, the PAG-CuS hydrogel reduced ROS levels, increased microvessel count, improved epithelialization, and enhanced wound healing. Therefore, this versatile photothermal hydrogel has the potential to be applied in sterilization, scavenging free radicals, and promoting angiogenesis, making it an effective and comprehensive solution to manage the challenges of diabetic wounds. Assessment of functional recovery and timely adjustment of treatment strategy is critical in the management of chronic diabetic wounds. In this work, we prepared PAG-CuS composite hydrogels by integrating in situ reduction, chemical crosslinking, and nanoenhancement techniques. The near-infrared light-induced photothermal effect of PAG-CuS gel rapidly kills bacteria at the lesion site, and the generated heat simultaneously promotes the multilevel release of LAS from the gel, which could regulate the levels of ROS and MMP-9 to promote extracellular matrix formation. In addition, the Cu2+ released from the gel can promote the formation of blood vessels to improve blood oxygenation. Therefore, this project proposes a synergistic solution to realize the whole process of management to accelerate chronic diabetic wound healing. [Display omitted] [ABSTRACT FROM AUTHOR]

A long-standing challenge in skeletal tissue engineering is to reconstruct a three-dimensionally (3D) interconnected bone cell network in vitro that mimics the native bone microarchitecture. While conventional hydrogels are extensively used in studying bone cell behavior in vitro , current techniques lack the precision to manipulate the complex pericellular environment found in bone. The goal of this study is to guide single bone cells to form a 3D network in vitro via photosensitized two-photon ablation of microchannels in gelatin methacryloyl (GelMA) hydrogels. A water-soluble two-photon photosensitizer (P2CK) was added to soft GelMA hydrogels to enhance the ablation efficiency. Remarkably, adding 0.5 mM P2CK reduced the energy dosage threshold five-fold compared to untreated controls, enabling more cell-compatible ablation. By employing low-energy ablation (100 J/cm2) with a grid pattern of 1 µm wide and 30 µm deep microchannels, we induced dendritic outgrowth in human mesenchymal stem cells (hMSC). After 7 days, the cells successfully utilized the microchannels and formed a 3D network. Our findings reveal that cellular viability after low-energy ablation was comparable to unablated controls, whereas high-energy ablation (500 J/cm2) resulted in 42 % cell death. Low-energy grid ablation significantly promoted network formation and >40 µm long protrusion outgrowth. While the broad-spectrum matrix metalloproteinase inhibitor (GM6001) reduced cell spreading by inhibiting matrix degradation, cells invaded the microchannel grid with long protrusions. Collectively, these results emphasize the potential of photosensitized two-photon hydrogel ablation as a high-precision tool for laser-guided biofabrication of 3D cellular networks in vitro. The inaccessible nature of osteocyte networks in bones renders fundamental research on skeletal biology a major challenge. This limit is partly due to the lack of high-resolution tools that can manipulate the pericellular environment in 3D cultures in vitro. To create bone-like cellular networks, we employ a two-photon laser in combination with a two-photon sensitizer to erode microchannels with low laser dosages into GelMA hydrogels. By providing a grid of microchannels, the cells self-organized into a 3D interconnected network within days. Laser-guided formation of 3D networks from single cells at micron-scale resolution is demonstrated for the first time. In future, we envisage in vitro generation of bone cell networks with user-dictated morphologies for both fundamental and translational bone research. [Display omitted] [ABSTRACT FROM AUTHOR]

Microneedles (MNs) are increasingly used in transdermal drug delivery due to high bioavailability, simple operation, and improved patient compliance. However, further clinical applications are hindered by unsatisfactory mechanical strength and uncontrolled drug release. Herein, an enzyme-mediated approach is reported for the fabrication of nanocomposite hydrogel-based MNs with tunable mechanical strength and controllable transdermal efficiency. As a proof-of-concept, tetrakis(1-methyl-4-pyridinio)porphyrin (TMPyP) was chosen as a model drug for photodynamic therapy of melanoma. TMPyP-loaded PLGA nanoparticles (NP/TMPyP) served as an inner phase of MNs for controlled release of photosensitizers, and enzyme-mediated hyaluronic acid-tyramine (HAT) hydrogels served as an external phase for optimizing the mechanical strength of MNs. By changing the concentration of HRP and H 2 O 2 , three types of MNs were fabricated for transdermal delivery of TMPyP, which demonstrated different cross-linking densities and various mechanical strength. Among the three MNs, the HAT-Medium@NP/TMPyP-MN with a medium mechanical strength exhibited the highest values of transdermal efficiency in vitro and the longest retention time in vivo. As compared to pure TMPyP and TMPyP-loaded nanoparticles, the HAT-Medium@NP/TMPyP-MN demonstrated higher anticancer efficacy in both melanoma A375 cells and a xenografted tumor mouse model. Therefore, the enzyme-mediated nanocomposite hydrogel MNs show great promise in the transdermal delivery of therapeutic drugs with enhanced performance. This study reports an enzyme-mediated approach for the fabrication of photodynamically-active microneedles (HAT@NP/TMPyP-MNs) with tunable mechanical strength and controllable transdermal efficiency. On one hand, HAT hydrogels that bear different cross-linking densities, facilitate tunable mechanical strength and optimized transdermal performances of MNs; on the other hand, NP/TMPyP and HAT network contribute to sustained release of photosensitizers. Comparing to other formulation (i.e., NP/TMPyP or TMPyP), the HAT-Medium@NP/TMPyP-MN exhibited excelling anticancer efficacy in photodynamic therapy in vitro and in vivo. We believe that the combination of enzyme-mediated polymeric cross-linking and slow-releasing nano-vehicles in a single nanocomposite platform provides a versatile approach for the fabrication of MNs with enhanced therapeutic efficacy, which holds great promise in the transdermal delivery of various therapeutic drugs in future. [Display omitted] [ABSTRACT FROM AUTHOR]

Plasma membrane isolation is a foundational process in membrane proteomic research, cellular vesicle studies, and biomimetic nanocarrier development, yet separation processes for this outermost layer are cumbersome and susceptible to impurities and low yield. Herein, we demonstrate that cellular cytosol can be chemically polymerized for decoupling and isolation of plasma membrane within minutes. A rapid, non-disruptive in situ polymerization technique is developed with cell membrane-permeable polyethyleneglycol-diacrylate (PEG-DA) and a blue-light-sensitive photoinitiator, lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP). The photopolymerization chemistry allows for precise control of intracellular polymerization and tunable confinement of cytosolic molecules. Upon cytosol solidification, plasma membrane proteins and vesicles are rapidly derived and purified as nucleic acids and intracellular proteins as small as 15 kDa are stably entrapped for removal. The polymerization chemistry and membrane derivation technique are broadly applicable to primary and fragile cell types, enabling facile membrane vesicle extraction from shorted-lived neutrophils and human primary CD8 T cells. The study demonstrates tunable intracellular polymerization via optimized live cell chemistry, offers a robust membrane isolation methodology with broad biomedical utility, and reveals insights on molecular crowding and confinement in polymerized cells. Isolating the minute fraction of plasma membrane proteins and vesicles requires extended density gradient ultracentrifugation processes, which are susceptible to low yield and impurities. The present work demonstrates that the membrane isolation process can be vastly accelerated via a rapid, non-disruptive intracellular polymerization approach that decouples cellular cytosols from the plasma membrane. Following intracellular polymerization, high-yield plasma membrane proteins and vesicles can be derived from lysis buffer and sonication treatment, respectively. And the intracellular content entrapped within the polymerized hydrogel is readily removed within minutes. The technique has broad utility in membrane proteomic research, cellular vesicle studies, and biomimetic materials development, and the work offers insights on intracellular hydrogel-mediated molecular confinement. [Display omitted] [ABSTRACT FROM AUTHOR]

Intimal hyperplasia is a common lesion that can be observed in diverse vascular diseases. Drug-eluting stents and drug-coated balloons, which can release anti-proliferative agents to inhibit smooth muscle cell (SMC) proliferation, are developed to prevent intimal hyperplasia. However, these intervention devices still cannot achieve satisfactory clinical outcomes. In contrast to endovascular drug delivery, vascular adventitial drug delivery is a new strategy. To develop a vascular adventitial drug delivery system to treat intimal hyperplasia post vascular injuries, we loaded miR-145-5p-agomir (miR-145) into an injectable and in-situ self-assembling RAD peptide hydrogel. In vitro data showed that the miR-145 could be well incorporated into the RAD peptide hydrogels and released in a slow and controlled manner. The released miR-145 could transfect SMCs successfully, and the transfected SMCs exhibited a reduced migration capacity and higher expressions of SMC contractile biomarkers as compared to the non-transfected SMCs. In vivo data showed that the retention of the miR-145 was greatly elongated by the RAD peptide hydrogels. In addition, the application of the miR-145-loaded RAD peptide hydrogels surrounding injured arteries decreased the proliferative SMCs, promoted the regeneration of endothelium, reduced the macrophage infiltration, inhibited the neointimal formation and prevented adverse ECM remodeling via downregulation of KLF4 expression. The RAD peptide hydrogels loaded with miR-145 can successfully inhibit intimal hyperplasia after vascular injuries and thus hold great potential as an innovative extravascular drug delivery approach to treat vascular diseases. Intimal hyperplasia is a common lesion that can be observed in diverse vascular diseases. Drug-eluting stents and drug-coated balloons, which can release anti-proliferative agents to inhibit smooth muscle cell (SMC) proliferation, are developed to prevent intimal hyperplasia. However, these intervention devices still cannot achieve satisfactory clinical outcomes. In contrast to endovascular drug delivery, vascular adventitial drug delivery is a new strategy. Our work here demonstrates that the RAD peptide hydrogels loaded with miR-145-5p-agomir (miR-145) can successfully reverse intimal hyperplasia after vascular injuries and thus hold great potential as an innovative vascular adventitial drug delivery approach to treat vascular diseases. Our work proposes a possible paradigm shift from endovascular drug delivery to extravascular drug delivery for vascular disorder treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Enterocutaneous fistula (ECF) is a severe medical condition where an abnormal connection forms between the gastrointestinal tract and skin. ECFs are, in most cases, a result of surgical complications such as missed enterotomies or anastomotic leaks. The constant leakage of enteric and fecal contents from the fistula site leads to skin breakdown and increases the risk of infection. Despite advances in surgical techniques and postoperative management, ECF accounts for significant mortality rates, estimated between 15 and 20 %, and causes debilitating morbidity. Therefore, there is a critical need for a simple and effective method to seal and heal ECFs. Injectable hydrogels with combined properties of robust mechanical properties and cell infiltration/proliferation have the potential to block and heal ECFs. Herein, we report the development of an injectable nanoengineered adhesive hydrogel (INAH) composed of a synthetic nanosilicate (Laponite®) and a gelatin-dopamine conjugate for treating ECFs. The hydrogel undergoes fast cross-linking using a co-injection method, resulting in a matrix with improved mechanical and adhesive properties. INAH demonstrates appreciable blood clotting abilities and is cytocompatible with fibroblasts. The adhesive properties of the hydrogel are demonstrated in ex vivo adhesion models with skin and arteries, where the volume stability in the hydrated internal environment facilitates maintaining strong adhesion. In vivo assessments reveal that the INAH is biocompatible, supporting cell infiltration and extracellular matrix deposition while not forming fibrotic tissue. These findings suggest that this INAH holds promising translational potential for sealing and healing ECFs. This research manuscript presents a groundbreaking INAH for treating ECFs. The INAH, composed of a synthetic nanosilicate and gelatin-dopamine conjugate, offers versatile implications in tissue regeneration and localized drug delivery. Acting as a scaffold, the shear-thinning hydrogel enables easy injection, forming a stable structure that supports tissue regeneration and integrates with surrounding tissues. By incorporating bioactive cues, it guides cell behavior and promotes functional tissue regeneration. The INAH also demonstrates potential for localized drug delivery, releasing therapeutic agents over time to enhance efficacy and minimize side effects. This research showcases INAH as a promising solution for ECFs, with applications in tissue engineering and regenerative medicine, marking a significant advancement in the field. [Display omitted] [ABSTRACT FROM AUTHOR]

In cases of blinding disease or trauma, hydrogels have been proposed as scaffolds for corneal regeneration and vehicles for ocular drug delivery. Restoration of corneal transparency, augmenting a thin cornea and postoperative drug delivery are particularly challenging in resource-limited regions where drug availability and patient compliance may be suboptimal. Here, we report a bioengineered hydrogel based on porcine skin collagen as an alternative to human donor corneal tissue for applications where long-term stability of the hydrogel is required. The hydrogel is reinforced with cellulose nanofibers extracted from the Ciona intestinalis sea invertebrate followed by double chemical and photochemical crosslinking. The hydrogel is additionally loaded with dexamethasone to provide sustained anti-inflammatory activity. The reinforced double-crosslinked hydrogel after drug loading maintained high optical transparency with significantly improved mechanical characteristics compared to non-reinforced hydrogels, while supporting a gradual sustained drug release for 60 days in vitro. Dexamethasone, after exposure to crosslinking and sterilization procedures used in hydrogel production, inhibited tube formation and cell migration of TNFα-stimulated vascular endothelial cells. The drug-loaded hydrogels suppressed key pro-inflammatory cytokines CCL2 and CXCL5 in TNFα-stimulated human corneal epithelial cells. Eight weeks after intra-stromal implantation in the cornea of 12 New-Zealand white rabbits subjected to an inflammatory suture stimulus, the dexamethasone-releasing hydrogels suppressed TNFα, MMP-9, and leukocyte and fibroblast cell invasion, resulting in reduced corneal haze, sustained corneal thickness and stromal morphology, and reduced overall vessel invasion. This collagen-nanocellulose double-crosslinked hydrogel can be implanted to treat corneal stromal disease while suppressing inflammation and maintaining transparency after corneal transplantation. To treat blinding diseases, hydrogel scaffolds have been proposed to facilitate corneal restoration and ocular drug delivery. Here, we improve on a clinically tested collagen-based scaffold to improve mechanical robustness and enzymatic resistance by incorporating sustainably sourced nanocellulose and dual chemical-photochemical crosslinking to reinforce the scaffold, while simultaneously achieving sustained release of an incorporated anti-inflammatory drug, dexamethasone. Evaluated in the context of a corneal disease model with inflammation, the drug-releasing nanocellulose-reinforced collagen scaffold maintained the cornea's transparency and resisted degradation while suppressing inflammation postoperatively. This biomaterial could therefore potentially be applied in a wider range of sight-threatening diseases, overcoming suboptimal administration of postoperative medications to maintain hydrogel integrity and good vision. [Display omitted] [ABSTRACT FROM AUTHOR]

Guanosine is often used to construct supramolecular hydrogels due to its self-assembly properties, however, the high temperature and strong alkaline construction methods greatly limit its application in biomedical fields. In this work, a guanosine-driven hyaluronic acid-based supramolecular hydrogel was developed under mild condition by employing phenylboronic acid-functionalized hyaluronic acid (HA-PBA) backbone and guanosine molecules. Guanosines self-assembled into G-quartet planes under potassium ion conditions, and formed boronic ester bonds with HA-PBA, which induced rapid formation of dynamically cross-linked hydrogels. Hemin was then binding to the G-quartet plane via π-π interactions in the hydrogels, which exhibited peroxidase activity and were highly effective in killing bacteria by generating hydroxyl radicals in the presence of H 2 O 2. Furthermore, glucose oxidase (GOx) was incorporated into the hydrogels and the HP/G@hemin@GOx hydrogels showed good antibacterial properties, modulation of wound glucose and ROS level, and good therapeutic efficacy for diabetic chronic wounds. Overall, the self-assembly of guanosine has been shown for the first time to be a feasible method for constructing natural polymer-based supramolecular hydrogels. This guanosine-driven HA-based supramolecular hydrogel can act as a potential wound dressing for chronic diabetic wound treatment. Chronic wound repair remains an unsolved clinical challenge. Herein, we propose to utilize phenylboronic acid-modified hyaluronic acid and guanosine to construct supramolecular gels with peroxidase activity for chronic wound treatment. The self-assembly behavior of guanosine drives the natural macromolecular backbone to form the hydrogel, and the proposed method simplifies the gelation conditions and improves its biosafety. The G-quartets formed by the self-assembly of guanosine can act as the loading site for hemin. G-quartet/hemin complex imported peroxidase activity to the hydrogels, endowing them with the ability to kill bacteria and regulate ROS levels of cells in the wound site. This guanosine-driven supramolecular hydrogel significantly increased the rate of wound healing in diabetic mice, promising a new strategy for chronic wound treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

A versatile hydrogel was developed for enhancing bioactive wound healing by introducing the amphiphilic GHK peptide (GHK-C16) into a photo-crosslinkable tyramine-modified hyaluronic acid (HA-Ty). GHK-C16 self-assembled into GHK nanofibers (GHK NF) in HA-Ty solution, which underwent in situ gelation after the wound area was filled with precursor solution. Blue light irradiation (460–490 nm), with riboflavin phosphate as a photoinitiator, was used to trigger crosslinking, which enhanced the stability of the highly degradable hyaluronic acid and enabled sustained release of the nanostructured GHK derivatives. The hydrogels provided a microenvironment that promoted the proliferation of dermal fibroblasts and the activation of cytokines, leading to reduced inflammation and increased collagen expression during wound healing. The complexation of Cu2+ into GHK nanofibers resulted in superior wound healing capabilities compared with non-lipidated GHK peptide with a comparable level of growth factor (EGF). Additionally, nanostructured Cu-GHK improved angiogenesis through vascular endothelial growth factor (VEGF) activation, which exerted a synergistic therapeutic effect. Furthermore, in vivo wound healing experiments revealed that the Cu-GHK NF/HA-Ty hydrogel accelerated wound healing through densely packed remodeled collagen in the dermis and promoting the growth of denser fibroblasts. HA-Ty hydrogels incorporating GHK NF also possessed improved mechanical properties and a faster wound healing rate, making them suitable for advanced bioactive wound healing applications. By combining photo-crosslinkable tyramine-modified hyaluronic acid with self-assembled Cu-GHK-C16 peptide nanofibers (Cu-GHK NF), the Cu-GHK NF/HA-Ty hydrogel offers remarkable advantages over conventional non-structured Cu-GHK for wound healing. It enhances cell proliferation, migration, and collagen remodeling—critical factors in tissue regeneration. The incorporation of GHK nanofibers complexed with copper ions imparts potent anti-inflammatory effects, promoting cytokine activation and angiogenesis during wound healing. The Cu-GHK NF/hydrogel's unique properties, including in situ photo-crosslinking, ensure high customization and potency in tissue regeneration, providing a cost-effective alternative to growth factors. In vivo experiments further validate its efficacy, demonstrating significant wound closure, collagen remodeling, and increased fibroblast density. Overall, the Cu-GHK NF/HA-Ty hydrogel represents an advanced therapeutic option for wound healing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Ionizing radiation, commonly used for head and neck cancer treatment, typically damages the salivary glands, resulting in hyposalivation. The development of treatments to restore this lost function is crucial for improving the quality of life for patients suffering from this condition. To address this clinical need, we have developed an innovative hydrogel by chemically conjugating laminin-1 peptides (A99 and YIGSR) and growth factors, FGF-7 and FGF-10, to fibrin hydrogels. Our results demonstrate that FGF-7/10 and laminin-1 peptides fortified fibrin hydrogel [enhanced laminin-1 peptides fibrin hydrogel (Ep-FH)] promotes salivary gland regeneration and functionality by improving epithelial tissue organization, establishing a healthy network of blood vessels and nerves, while reducing fibrosis in a head and neck irradiated mouse model. These results indicate that fibrin hydrogel-based implantable scaffolds containing pro-regenerative signals promote sustained secretory function of irradiated salivary glands, offering a potential alternative treatment for hyposalivation in head and neck cancer patients undergoing radiation treatment. These unique findings emphasize the potential of fibrin hydrogel-based implantable scaffolds enriched with pro-regenerative signals in sustaining the secretory function of irradiated salivary glands and offer a promising alternative treatment for addressing hyposalivation in head and neck cancer patients undergoing radiation therapy. Radiation therapies used to treat head and neck cancers often result in damaged salivary gland, leading to severe dryness of the oral cavity. In this study, we engineered FGF-7 and FGF-10 and immobilized them into L 1p -FH. The resulting hydrogel, Ep-FH, restored irradiated salivary gland functionality by enhancing epithelial tissue organization, promoting the development of a healthy network of blood vessels and nerves as well as reduction of fibrosis. [Display omitted] [ABSTRACT FROM AUTHOR]

The field of cancer immunotherapy has shown significant growth, and researchers are now focusing on effective strategies to enhance and prolong local immunomodulation. Injectable hydrogels (IHs) have emerged as versatile platforms for encapsulating and controlling the release of small molecules and cells, drawing significant attention for their potential to enhance antitumor immune responses while inhibiting metastasis and recurrence. IHs delivering natural killer (NK) cells, T cells, and antigen-presenting cells (APCs) offer a viable method for treating cancer. Indeed, it can bypass the extracellular matrix and gradually release small molecules or cells into the tumor microenvironment, thereby boosting immune responses against cancer cells. This review provides an overview of the recent advancements in cancer immunotherapy using IHs for delivering NK cells, T cells, APCs, chemoimmunotherapy, radio-immunotherapy, and photothermal-immunotherapy. First, we introduce IHs as a delivery matrix, then summarize their applications for the local delivery of small molecules and immune cells to elicit robust anticancer immune responses. Additionally, we discuss recent progress in IHs systems used for local combination therapy, including chemoimmunotherapy, radio-immunotherapy, photothermal-immunotherapy, photodynamic-immunotherapy, and gene-immunotherapy. By comprehensively examining the utilization of IHs in cancer immunotherapy, this review aims to highlight the potential of IHs as effective carriers for immunotherapy delivery, facilitating the development of innovative strategies for cancer treatment. In addition, we demonstrate that using hydrogel-based platforms for the targeted delivery of immune cells, such as NK cells, T cells, and dendritic cells (DCs), has remarkable potential in cancer therapy. These innovative approaches have yielded substantial reductions in tumor growth, showcasing the ability of hydrogels to enhance the efficacy of immune-based treatments. As cancer immunotherapy continues to expand, the mode of therapeutic agent delivery becomes increasingly critical. This review spotlights the forward-looking progress of IHs, emphasizing their potential to revolutionize localized immunotherapy delivery. By efficiently encapsulating and controlling the release of essential immune components such as T cells, NK cells, APCs, and various therapeutic agents, IHs offer a pioneering pathway to amplify immune reactions, moderate metastasis, and reduce recurrence. Their adaptability further shines when considering their role in emerging combination therapies, including chemoimmunotherapy, radio-immunotherapy, and photothermal-immunotherapy. Understanding IHs' significance in cancer therapy is essential, suggesting a shift in cancer treatment dynamics and heralding a novel period of focused, enduring, and powerful therapeutic strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

Organoids are an emerging technology with great potential in human disease modelling, drug development, diagnosis, tissue engineering, and regenerative medicine. Organoids as 3D-tissue culture systems have gained special attention in the past decades due to their ability to faithfully recapitulate the complexity of organ-specific tissues. Despite considerable successes in culturing physiologically relevant organoids, their real-life applications are currently limited by challenges such as scarcity of an appropriate biomimetic matrix. Peptide amphiphiles (PAs) due to their well-defined chemistry, tunable bioactivity, and extracellular matrix (ECM)-like nanofibrous architecture represent an attractive material scaffold for organoids development. Using cerebral organoids (COs) as exemplar, we demonstrate the possibility to create bio-instructive hydrogels with tunable stiffness ranging from 0.69 kPa to 2.24 kPa to culture and induce COs growth. We used orthogonal chemistry involving oxidative coupling and supramolecular interactions to create two-component hydrogels integrating the bio-instructive activity and ECM-like nanofibrous architecture of a laminin-mimetic PAs (IKVAV-PA) and tunable crosslinking density of hyaluronic acid functionalized with tyramine (HA-Try). Multi-omics technology including transcriptomics, proteomics, and metabolomics reveals the induction and growth of COs in soft HA-Tyr hydrogels containing PA-IKVAV such that the COs display morphology and biomolecular signatures similar to those grown in Matrigel scaffolds. Our materials hold great promise as a safe synthetic ECM for COs induction and growth. Our approach represents a well-defined alternative to animal-derived matrices for the culture of COs and might expand the applicability of organoids in basic and clinical research. Synthetic bio-instructive materials which display tissue-specific functionality and nanoscale architecture of the native extracellular matrix are attractive matrices for organoids development. These synthetic matrices are chemically defined and animal-free compared to current gold standard matrices such as Matrigel. Here, we developed hydrogel matrices with tunable stiffness, which incorporate laminin-mimetic peptide amphiphiles to grow and expand cerebral organoids. Using multi-omics tools, the present study provides exciting data on the effects of neuro-inductive cues on the biomolecular profiles of brain organoids. [Display omitted] [ABSTRACT FROM AUTHOR]

A visible light- and reactive oxygen species (ROS)-responsive pressure/strain sensor based on carbon dot (CD)-loaded conductive hydrogel was developed for detecting high-fat diet (HFD) and preventing the risk of non-alcoholic fatty liver disease. The designed nanoparticle consisted of a diselenide polymer dot (dsPD) loaded with a visible light-responsive CD to form dsPD@CD (DSCD). The influence of visible light irradiation and ROS on DSCD facilitated the electron transport, enhancing the conductivity of DSCD-embedded hydrogel (DSCD hydrogel) from 1.3 to 35.9 mS/m. Alternatively, the tensile modulus of the DSCD hydrogel enhanced to 223 % after light-induced ROS treatment, which simultaneously impacted the capacitive response (120 %). The hydrogel implantation into inguinal white adipose tissue of HFD mice showed 82 % higher conductivity and 83 % enhanced pressure sensing response to HFD-generated high ROS levels compared with the normal diet-fed mice. Additionally, the ROS scavenging activity of DSCD hydrogel was confirmed by the downregulation of ROS-responsive genes, such as Sod2, Nrf2 , and catalase (Cat) in murine primary hepatocytes isolated from fatty liver-induced mice. In addition, in vivo animal studies also confirmed the suppression of hepatic lipogenesis, as shown by decreased Pparγ and Fasn expression and hypertrophy of adipocytes in HFD mice. The distinguishable real-time wireless resistance response observed with pressure sensing indicates the potential application of the device for monitoring the risk of non-alcoholic fatty liver disease. A visible-light-induced ROS-responsive carbon dot-loaded conductive hydrogel was developed for the detection of HFD-induced alterations in ROS levels by evaluating the conductivity and electrochemical responses with applied pressure/strain. The implanted hydrogel facilitates the recovery of the inflated adipocytes induced by NAFLD, which reduces fat accumulation in the liver, preventing the risk of NAFLD. Real-time detection based on the resistance response during local compression of the hydrogel is possibly performed utilizing a wireless sensing device, demonstrating the ease of NAFLD monitoring. [Display omitted] [ABSTRACT FROM AUTHOR]

Retinal vascular diseases such as neovascular age-related macular degeneration (nAMD) are the leading cause of blindness worldwide. They can be treated with intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents by inhibiting VEGF which is a major agent of abnormal blood vessel growth. However, because of drug's short half-life, clinical treatment often requires monthly repeated intravitreal injections, causing treatment burden and undertreatment. Among various kinds of drug carriers, in situ forming hydrogels have been studied as potential intravitreal drug carriers for the high drug loading, easy injection, controlled drug release, and protection of encapsulated drugs from the environment. However, gelation time, crosslinking degree, and drug release patterns following injection of a liquid that will be subsequently gelled in situ are susceptible to be hindered by dilution of the hydrogel precursor solution with body fluids (e.g. , blood or vitreous). Here, we report an injectable pre-crosslinked hydrogel rod to overcome the limitations of in situ forming hydrogels and to extend intravitreal half-life of anti-VEGF for reducing intraocular injection frequency. Hydrogel rods can be simply prepared using in situ forming hydrogels, and injectable using a designed rod injector. The adjustable crosslinking degree of hydrogel rods easily controlled bevacizumab release profiles in a sustained manner. Compared with in situ forming hydrogels, hydrogel rods effectively reduced initial burst release, and showed sustained release with long-term drug efficacy in vitro. From the 4-month in vivo pharmacokinetic analysis, following the intravitreal injection of hydrogel rods, the half-life of bevacizumab in the vitreous and retina was significantly extended, and drug elimination to aqueous humor was effectively reduced. Finally, intraocular stability, degradation, and inflammatory response of hydrogel rods were evaluated. We expect that the hydrogel rod can be a potential drug delivery system for the treatment of nAMD and other conditions that need long-term and local sustained drug administration. Herein, we report an injectable pre-crosslinked hydrogel rod based on an in situ forming hydrogel to achieve intravitreal long-acting anti-VEGF delivery to reduce injection frequency and improve the long-term visual outcomes of patients with retinal vascular diseases. Hydrogel rods were readily prepared using removable molds and injected using customized injectors. Compared to the in situ forming hydrogel, hydrogel rods showed significantly reduced initial burst release, controllable release profiles for several months, physical stability, and a long-acting anti-angiogenic effect. Animal studies demonstrated that the hydrogel rods dramatically prolonged the intraocular drug half-life while significantly reducing drug elimination for up to four months. Moreover, the biodegradability and safety of the hydrogel rods suggest their suitability as an advanced intravitreal DDS for treating retinal vascular diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

Corneal scarring and opacification are a significant cause of blindness affecting millions worldwide. The current standard of care for corneal blindness is corneal transplantation, which suffers from several drawbacks. One alternative approach that has shown promise is the use of xenogeneic corneal extracellular matrix (ECM), but its clinical applicability is challenging due to safety concerns. This study reports the innovative use of human cornea-derived ECM to prevent post-traumatic corneal scarring. About 30 - 40% of corneas donated to the eye banks do not meet the standards defined for clinical use and are generally discarded, although they are completely screened for their safety. In this study, human cornea-derived decellularized ECM hydrogel was prepared from the non-transplantation grade human cadaveric corneas obtained from an accredited eye-bank. The prepared hydrogel was screened for its efficacy against corneal opacification following an injury in an animal model. Our in vivo study revealed that, the control collagen-treated group developed corneal opacification, while the prophylactic application of human cornea-derived hydrogel effectively prevented corneal scarring and opacification. The human hydrogel-treated corneas were indistinguishable from healthy corneas and comparable to those treated with the xenogeneic bovine corneal hydrogel. We also demonstrated that the application of the hydrogel retained the biological milieu including cell behavior, protein components, optical properties, curvature, and nerve regeneration by remodeling the corneal wound after injury. The hydrogel application is also sutureless, resulting in faster corneal healing. We envision that this human cornea-derived ECM-based hydrogel has potential clinical application in preventing scarring from corneal wounding. There are significant challenges surrounding corneal regeneration after injury due to extensive scarring. Although there is substantial research on corneal regeneration, much of it uses synthetic materials with chemical cross-linking methods or xenogeneic tissue-based material devices which have to undergo exhaustive safety analysis before clinical trials. Herein, we demonstrate the potential application of a human corneal extracellular matrix hydrogel without any additional materials for scarless corneal tissue regeneration, and a method to reduce the wasting of donated allogenic corneal tissue from eye banks. We found no difference in efficacy between the usage of human tissues compared to xenogeneic sources. This may help ease clinical translation and can be used topically without sutures as an outpatient procedure. [Display omitted] [ABSTRACT FROM AUTHOR]