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Patients with diabetes suffer from a variety of complications and easily develop diabetic chronic wounds. The microenvironment of diabetic wounds is characterized by an excessive amount of reactive oxygen species (ROS) and an imbalance of proinflammatory and anti-inflammatory cells/factors, which hinder the regeneration of chronic wounds. In the present study, a wound dressing with immunomodulation and electroconductivity properties was prepared and assayed in vitro and in vivo. [2-(acryloyloxy) ethyl] Trimethylammonium chloride (Bio-IL) and gelatin methacrylate (GelMA) were 3D printed onto a doxycycline hydrochloride (DOXH)-loaded and ROS-degradable polyurethane (PFKU) nanofibrous membrane, followed by UV irradiation to obtain conductive hydrogel strips. DOXH was released more rapidly under a high ROS environment. The dressing promoted migration of endothelial cells and polarization of macrophages to the anti-inflammatory phenotype (M2) in vitro. In a diabetic rat wound healing test, the combination of conductivity and DOXH was most effective in accelerating wound healing, collagen deposition, revascularization, and re-epithelialization by downregulating ROS and inflammatory factor levels as well as by upregulating the M2 macrophage ratio. STATEMENT OF SIGNIFICANCE: The microenvironment of diabetic wounds is characterized by an excessive amount of reactive oxygen species (ROS) and an imbalance of proinflammatory and anti-inflammatory cells/factors, which hinder the regeneration of chronic wounds. Herein, a wound dressing composed of a DOXH-loaded ROS-responsive polyurethane membrane and 3D-printed conductive hydrogel strips was prepared, which effectively accelerated skin regeneration in diabetic wounds in vivo with better epithelialization, angiogenesis, and collagen deposition. DOXH regulated the dysfunctional wound microenvironment by ROS scavenging and polarizing macrophages to M2 phenotype, thereby playing a dominant role in diabetic wound regeneration. This design may have great potential for preparing other similar materials for the therapy of other diseases with excessive inflammation or damage to electrophysiological organs, such as nerve defect and myocardial infarction.

There are limited naturally derived protein biomaterials for the available medical implants. High cost, low yield, and batch-to-batch inconsistency, as well as intrinsically differing bioactivity in some of the proteins, make them less beneficial as common implant materials compared to their synthetic counterparts. Here, we present a milk-derived whey protein isolate (WPI) as a new kind of natural protein-based biomaterial for medical implants. The WPI was methacrylated at 100 g bench scale,95% conversion, and 90% yield to generate a photo-cross-linkable material. WPI-MA was further processed into injectable hydrogels, monodispersed microspheres, and patterned scaffolds with photo-cross-linking-based advanced processing methods including microfluidics and 3D printing. In vivo evaluation of the WPI-MA hydrogels showed promising biocompatibility and degradability. Intramyocardial implantation of injectable WPI-MA hydrogels in a model of myocardial infarction attenuated the pathological changes in the left ventricle. Our results indicate a possible therapeutic value of WPI-based biomaterials and give rise to a potential collaboration between the dairy industry and the production of medical therapeutics.

Immunomodulation is an important phenomenon in the normal mammalian host response toward an injury, and plays a critical role in tissue regeneration and regenerative medicine. Different phenotypes of macrophages show an array of activation states compassing pro-inflammatory to pro-alleviating cells, which are the critical players to modulate immune response and tissue regeneration. In this study, macrophage membranes of different phenotypes (macrophages (M0), classically activated macrophages (M1) and alternatively activated macrophages (M2)) were coated onto poly-ε-caprolactone (PCL) nanofibers to acquire exterior surface proteins and similar functions of the natural membranes. In vitro results unveiled that these nanofibers, especially the M2-PCL nanofibers, can suppress the activities of inflammatory markers such as TNF-α and IL-1β, and stimulate anti-inflammatory markers such as Arg-1, IL-10 and TGF-β. In a C57BL/6 mouse model, the macrophage membrane-coated nanofibers, especially the M2-PCL nanofibers, displayed minimal cellular infiltration and low collagen deposition, increased anti-inflammatory CD206 and decreased inflammatory CD86 levels. The M2-PCL nanofibers most effectively neutralized inflammatory chemokines, regulated the expression of inflammation-associated genes as well as anti-inflammatory genes, and showed strong immunomodulatory effects than the PCL, M0-PCL and M1-PCL nanofibers. STATEMENT OF SIGNIFICANCE: Different types of macrophage membrane-functionalized PCL nanofibers were successfully prepared and well characterized. They inherited the surface proteins imitating the source macrophages, and played an important role in limiting cellular infiltration and collagen deposition. These different macrophages and their membrane-coated nanofibers (M0-PCL, M1-PCL and M2-PCL) behaved like their respective source cells. The M2 mimicking M2-PCL nanofibers effectively polarized macrophages to M2 phenotype and decreased the expression of inflammation-associated chemokines and promoted the anti-inflammation in vitro and in vivo, which is critical for tissue regeneration. The mice implanted with the bio-mimicking M2-PCL nanofibers effectively inhibited toll like receptors signaling induced NF-kB and IRF-5 and their target genes such as Edn-1, IL-6, iNOS, TNF-α, etc. compared to the PCL, and M0-PCL and M1-PCL macrophage membrane-coated nanofibers.

Weak tissue adhesion remains a major challenge in clinical translation of microneedle patches. Mimicking the structural features of honeybee stingers, stiff polymeric microneedles with unidirectionally backward-facing barbs were fabricated and embedded into various elastomer films to produce self-interlocking microneedle patches. The spirality of the barbing pattern was adjusted to increase interlocking efficiency. In addition, the micro-bleeding caused by microneedle puncturing adhered the porous surface of the patch substrate to the target tissue via coagulation. In the demonstrative application of myocardial infarction treatment, the bioinspired microneedle patches firmly fixed on challenging beating hearts, significantly reduced cardiac wall stress and strain in the infarct, and maintained left ventricular function and morphology. In addition, the microneedle patch was minimally invasively implanted onto beating porcine heart in 10 minutes, free of sutures and adhesives. Therefore, the honeybee stinger-inspired microneedles could provide an adaptive and convenient means to implant patches for various medical applications. STATEMENT OF SIGNIFICANCE: Adhesion between tissue and microneedle patches with smooth microneedles is usually weak. We introduce a novel barbing method of fabricating unidirectionally backward facing barbs with controllable spirality on the microneedles on microneedle patches. The microneedle patches self-interlock on mechanically dynamic beating hearts, similar to honeybee stingers. The micro-bleeding and coagulation on the porous surface provide additional adhesion force. The microneedle patches attenuate left ventricular remodeling via mechanical support and are compatible with minimally invasive implantation.

The regeneration of osteochondral defects faces great challenges because of the limited self-regenerative capabilities of cartilage tissues. In situ inductive regeneration can be realized using bioactive scaffolds combined with endogenous reparative cells. Cell migration could be significantly facilitated by scaffolds with oriented channels. For this purpose, silk fibroin (SF) was composited with collagen (Col) to fabricate extracellular matrix (ECM)-mimetic SF/Col composite scaffolds with random pores, radially aligned pores or axially aligned pores by ice-templated assembly and temperature gradient-guided thermally-induced phase separation. Scanning electron microscopy (SEM) observation confirmed the random and aligned architectures in the respective scaffolds. The three kinds of SF/Col composite scaffolds exhibited a porous structure with a porosity of ∼85%, an appropriate elastic modulus with mechanical anisotropy in the aligned scaffolds, and good biocompatibility. The oriented channels could improve in vivo cell migration and infiltration. During the tissue remodeling processes, the regeneration of osteochondral tissues particularly cartilage was obviously faster in the radially aligned scaffold group than in the other two groups. Nevertheless, satisfactory regeneration was achieved in the two aligned scaffold groups with hyaline cartilage formation at 18 weeks post-surgery, while a hybrid of hyaline cartilage and fibrocartilage was formed in the random scaffold group.

The osteoarthritis (OA) symptoms cannot be fully remedied by using only a single functional component because of its complex pathogenesis. Herein, a MnO

Myocardial infarction (MI) is still a major cause of mortality and morbidity worldwide. Elastomer cardiac patches have shown great potential in preventing left ventricle (LV) remodeling post-MI by providing mechanical support to the infarcted myocardium. Improved therapeutic outcomes are expected by mediating pathological processes in the necrosis phase, inflammation phase, and fibrosis phase, through orchestrated biological and mechanical treatments. In this study, a mechanically robust multifunctional cardiac patch integrating reactive oxygen species (ROS)-scavenging, anti-inflammatory, and pro-angiogenic capabilities was developed to realize the integrative strategy. An elastomeric polyurethane (PFTU) containing ROS-sensitive poly (thioketal) (PTK) and unsaturated poly (propylene fumarate) (PPF) segments was synthesized, which was further clicked with pro-angiogenic Arg-Glu-Asp-Val (REDV) peptides to obtain PFTU-g-REDV (PR), and was formulated into a macroporous patch containing rosuvastatin (PRR). The mechanical support and multifunctional effects of the patch were confirmed in a rat MI model in vivo compared to the patches with only mechanical support, leading to reduced cell apoptosis, suppressed local inflammatory response, alleviated fibrosis, and induced angiogenesis. The cardiac functions and LV morphology were also well maintained. These results demonstrate the advantages of the integrated and orchestrated treatment strategy in MI therapy.

Immune response is critical to tissue repair. Designing biomaterials with immunomodulatory functions has become a promising strategy to facilitate tissue repair. Considering the key roles of macrophages in tissue repair and the significance of the balance of M1 and M2, smart biomaterials, which can harness macrophage phenotypes dynamically to match the tissue healing process on demand, have attracted a lot of attention to be set apart from the traditional anti-inflammatory biomaterials. Here, we prepare a gold nanorod-contained shape memory polycaprolactone film with dynamic surface topography, which has the ability to be transformed from flat to microgrooved under near-infrared (NIR) irradiation. Based on the close relationships between the morphologies and the phenotypes of macrophages, the NIR-triggered surface transformation induces the elongation of macrophages, and consequently the upregulated expressions of arginase-1 and IL-10 in vitro, indicating the change of macrophage phenotypes. The sequential modulation of macrophage phenotypes by dynamic surface topography is further confirmed in an in vivo implantation test. The healing-matched modulation of macrophage phenotypes by dynamic surface topography without the stimuli of cytokines offers an effective and noninvasive strategy to manipulate tissue regenerative immune reactions to achieve optimized healing outcomes.

In women of reproductive age, severe injuries to the endometrium are often accompanied by endometrial scar formation or intrauterine adhesions (IUAs), which can result in infertility or miscarriage. Although many approaches have been used to treat severe IUAs, high recurrence rates and endometrial thinning have limited therapeutic efficiency. In this study, a collagen scaffold (CS) loaded with human umbilical cord-derived mesenchymal stem cells (UC-MSCs) was fabricated and applied for endometrial regeneration. The CS/UC-MSCs promoted human endometrial stromal cell proliferation and inhibited apoptosis in vitro through paracrine effects. In a model of endometrial damage, transplantation with the CS/UC-MSCs maintained normal luminal structure, promoted endometrial regeneration and collagen remodeling, induced intrinsic endometrial cell proliferation and epithelium recovery, and enhanced the expression of estrogen receptor α and progesterone receptor. An improved ability of the regenerated endometrium to receive embryos was confirmed. Together, our results indicate that the CS/UC-MSCs promoted endometrial structural reconstruction and functional recovery. Topical administration of the CS/UC-MSCs after trans-cervical resection of adhesions might prevent re-adhesion, promote endometrium regeneration and improve pregnancy outcomes for patients with severe IUAs. STATEMENT OF SIGNIFICANCE: Intrauterine adhesions due to severe endometrium injuries happen frequently in clinic and become one of the crucial reasons for women's infertility or miscarriage. Therefore, how to regenerate the damaged endometrium is a big challenge. In this study, a collagen scaffold (CS) loaded with human umbilical cord-derived mesenchymal stem cells (UC-MSCs) was fabricated and applied for endometrium regeneration. Herein, UC-MSCs, known for low immunogenicity and high proliferative potential, exhibit promising potential for endometrium regeneration; and collagen scaffolds provide suitable physical support. It was proved that transplantation with CS/UC-MSCs promoted endometrial regeneration and fertility restoration. It suggested that topical administration of CS/UC-MSCs in uterus could be a promising strategy for patients suffering severe intrauterine adhesion and infertility.

We have developed the new core-shell bioceramic CSi-Sr4@CaP-px microspheres with tuning porous shell layer so that the biodegradation of both CSi-Sr4 core and CaP shell is readily adjusted synergistically. This is for the first time, to the best of our knowledge, that the bioceramic scaffolds concerning gradient distribution and microstructure-tailoring design is available for tailoring biodegradation and ion release (bioactivity) to optimizing osteogenesis. Furthermore, it is possibly helpful to develop new bioactive scaffold system for time-dependent tailoring bioactivity and microporous structure to significantly enhance bone regeneration and repair applications, especially in some non-load-bearing arbitrary 3D anatomical bone and teeth defects.

The ability of repair and regeneration of tissues or organs has been significantly improved by using biomaterials-based constructs. Our previous studies found the regeneration of both articular cartilage and subchondral bone by implantation of a poly(lactide-co-glycolide) (PLGA)/fibrin gel/bone marrow stem cells (BMSCs)/(lipofectamine/pDNA-transforming growth factor (TGF)-β1) construct in vivo, without the step of pre-induced differentiation of the laden stem cells in vitro. To substantiate the ability to regenerate multi-types of tissues by the same constructs, in this study the constructs were implanted into three types of tissues or tissue defects in vivo, including subcutaneous fascia layer, and ear cartilage and eyelid tarsal plate defects. The ear cartilage and eyelid tarsal plate defects were fully regenerated 8 w post-implantation, showing a similar morphology to the corresponding native tissues. In the neo ear cartilage, abundant chondrocytes with obvious lacunas and cartilage-specific extracellular matrices (ECMs) were found. Neo eyelid tarsal plate with mature meibomian gland acinar units was regenerated. Furthermore, expressions of the ECMs-specific genes and proteins, as well as the cell behavior modulatory factors, Sry related HMG box 9 (Sox9) and TGF-β1 were significantly up-regulated in the regenerated ear cartilages and eyelid tarsal plate than those in the subcutaneously implanted constructs, which were filled with fibrocytes, inflammatory cells, obvious vascularization and slight ECMs deposition. These results confirm firmly the ability to regenerate multi-types of tissues by a stem cells-laden construct via adapting to the microenvironments of corresponding tissues.

The modulation of inflammation in tissue microenvironment takes an important role in cartilage repair and regeneration. In this study, a novel hybrid scaffold was designed and fabricated by filling a reactive oxygen species (ROS)-scavenging hydrogel (RS Gel) into a radially oriented poly(lactide-co-glycolide) (PLGA) scaffold. The radially oriented PLGA scaffolds were fabricated through a temperature gradient-guided phase separation and freeze-drying method. The RS Gel was formed by crosslinking the mixture of ROS-responsive hyperbranched polymers and biocompatible methacrylated hyaluronic acid (HA-MA). The hybrid scaffolds exhibited a proper compressive modulus, good ROS-scavenging capability, and cell compatibility.In vivotests showed that the hybrid scaffolds significantly regulated inflammation and promoted regeneration of hyaline cartilage after they were implanted into full-thickness cartilage defects in rabbits for 12 w. In comparison with the PLGA scaffolds, the neo-cartilage in the hybrid scaffolds group possessed more deposition of glycosaminoglycans and collagen type II, and were well integrated with the surrounding tissue.

Cellular metabolism plays a major role in the regulation of inflammation. The inflammatory macrophages undergo a wide-range of metabolic rewriting due to the production of significant amount of itaconate metabolite from cis-aconitate in the tricarboxylic acid cycle. This itaconate molecule has been recently described as a promising immunoregulator. However, its function and mode of action on macrophages and tissue repair and regeneration are yet unclear. Herein, the itaconate-derivative dimethyl itaconate (DMI) suppresses the IL-23/IL-17 inflammatory axis-associated genes and promotes antioxidant nuclear factor erythroid 2-related factor 2 target genes. The poly-e-caprolactone (PCL)/DMI nanofibers implanted in mice initially maintain inflammation by suppressing anti-inflammatory activity and particular inflammation, while at later stage promotes anti-inflammatory activity for an appropriate tissue repair. Furthermore, the PCL/DMI nanofiber patches show an excellent myocardial protection by reducing infarct area and improving ventricular function via time-dependent regulation of myocardium-associated genes. This study unveils potential DMI macrophage modulatory functions in tissue microenvironment and macrophages rewriting for proper tissue repair.

The excessive reactive oxygen species (ROS) and hypoxia deteriorate the inflammation-related diseases such as myocardial infarction (MI), and thereby deter the normal tissue repair and recovery and further lead to severe fibrosis and malfunction of tissues and organs. In particular, the MI has become one of the leading causes of death nowadays. In this study, a novel type of injectable hydrogel with dual functions of ROS scavenging and O

The dual functional implants of antibacteria and osteointegration are highly demanded in orthopedic and dentistry, especially for patients who suffer from diabetes or osteoporosis simultaneously. However, there is lack of the facile and robust method to produce clinically applicable implants with this dual function although coatings possessing single function have been extensively developed. Herein, hyperbranched poly-L-lysine (HBPL) polymers were covalently immobilized onto the alkali-heat treated titanium (Ti) substrates and implants by using 3-glycidyloxypropyltrimethoxysilane (GPTMS) as the coupling agent, which displayed excellent antibacterial activity against S. aureus and E. coli with an efficiency as high as 89.4% and 92.2% in vitro, respectively. The HBPL coating also significantly promoted the adhesion, spreading, proliferation and osteogenic differentiation of MC3T3-E1 cells in vitro. Furthermore, the results of a S. aureus infection rat model in vivo ulteriorly verified that the HBPL-modified screws had good antibacterial and anti-inflammatory abilities at an early stage of implantation and better osteointegration compared with the control Ti screws.

Due to the poor self-repair capabilities of articular cartilage, chondral or osteochondral injuries are difficult to be recovered. In this study, an N-cadherin mimetic peptide sequence HAVDIGGGC (HAV) was conjugated to direct cell–cell interactions, and an aggrecanase-1 cleavable peptide sequence CRDTEGE-ARGSVIDRC (ACpep) was used to crosslink hyperbranched PEG-based multi-acrylate polymer (HBPEG) with cysteamine-modified chondroitin sulfate (Cys-CS), obtaining an aggrecanase-1 responsively degradable and HAV-conjugated hydrogel ((HAV-HBPEG)-CS-ACpep). A HBPEG-CS-ACpep hydrogel without the HAV motif was also prepared. The two hydrogels exhibited similar equilibrium swelling ratios, elastic moduli and pore sizes after lyophilization, indicating the negligible influence of conjugated HAV on the crosslinking networks and mechanical properties of the hydrogels. After being degraded in PBS, aggrecanase-1 (ADAMTS4) and trypsin, the HBPEG-CS-ACpep hydrogel exhibited significantly decreased elastic moduli with a much lower value when incubated in enzyme solutions. The two hydrogels could maintain the viability of encapsulated bone marrow-derived mesenchymal stem cells (BMSCs), and the (HAV-HBPEG)-CS-ACpep hydrogel better promoted the cell–cell interactions. After being implanted into osteochondral defects in rabbits for 18 weeks, the two cell-laden hydrogel groups achieved better repair effects than the blank control group. Moreover, hyaline cartilage was formed in the (HAV-HBPEG)-CS-ACpep/BMSCs hydrogel group, while a hybrid of hyaline cartilage and fibrocartilage was found in the HBPEG-CS-ACpep/BMSCs hydrogel group.

Regeneration and functional recovery of peripheral nerves remain formidable due to the inefficient physical and chemical cues in the available nerve guidance conduits (NGCs). Introducing micropatterns and bioactive substances into the inner wall of NGCs can effectively regulate the behavior of Schwann cells, the elongation of axons, and the phenotype of macrophages, thereby aiding the regeneration of injured nerve. In this study, linear micropatterns with ridges and grooves of 3/3, 5/5, 10/10, and 30/30 μm were created on poly(d,l-lactide

Bacterial infection is a major obstacle to the wound healing process. The hydrogel dressings with a simpler structure and good antibacterial and wound healing performance are appealing for clinical application. Herein, a robust hydrogel was synthesized from acrylamide (AM), acrylic acid (AA) and N,N′-methylene diacrylamide (MBA) via a redox initiating polymerization. The polymerization conditions were optimized to obtain the hydrogel with minimum unreacted monomers, which were 0.25% and 0.12% for AM and AA, respectively. The hydrogel had good mechanical strength, and could effectively resist damage by external forces and maintain a good macroscopic shape. It showed large water uptake capacity, and could post load a wide range of molecules via hydrogen bonding and electrostatic interaction. Loading of antibiotic doxycycline (DOX) enabled the hydrogel with good antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria in vitro and in vivo. In a rat model of methicillin-resistant Staphylococcus aureus (MRSA)-infected full-thickness skin defect wound, the DOX-loaded hydrogel showed good therapeutic effect. It could significantly promote the wound closure, increased the collagen coverage area, down-regulate the expressions of pro-inflammatory TNF-α and IL-1β factors, and up-regulate the expressions of anti-inflammatory IL-4 factor and CD31 neovascularization factor.

Photodynamic therapy is an effective alternative to traditional treatments due to its minimally invasive nature, negligible systemic toxicity, fewer side effects, and avoidance of drug resistance. However, it is still challenging to design photosensitizers with high singlet oxygen (1O2) quantum yields (QY) due to severe aggregation of the hydrophobic photosensitizers. Herein, we developed a discrete organoplatinum(II) metallacage using therapeutic cis-(PEt3)2Pt(OTf)2 as the building block to improve the 1O2 QY, thus achieving synergistic anticancer efficacy. The metallacage-loaded nanoparticles (MNPs) with tri-modality imaging capability allow precise diagnosis of tumor and real-time monitoring the delivery, biodistribution, and excretion of the MNPs. MNPs exhibited excellent anti-metastatic effect and superior anti-tumor performance against U87MG, drug resistant A2780CIS, and orthotopic tumor models, ablating the tumors without recurrence after a single treatment. Gene chip analyses confirmed the contribution of different therapeutic modalities to the tumor abrogation. This supramolecular platform holds potential in precise cancer theranostics., It is challenging to design photosensitizers (PS) with high quantum yields generating singlet oxygen due to severe aggregation between the hydrophobic PSs. Here they develop organoplatinum(II) metallatocage-based PS to overcome these challenges and show excellent antitumor effect.

Methicillin-resistant Staphylococcus aureus (MRSA) has been one of the major nosocomial pathogens to cause frequent and serious infections that are associated with various biomedical surfaces. This study demonstrated that surface modified with host defense peptide-mimicking β-peptide polymer, has surprisingly high bactericidal activities against Escherichia coli (E. coli) and MRSA. As surface-tethered β-peptide polymers cannot move freely to adopt the collaborative interactions with bacterial membrane and are too short to penetrate the cell envelop, we proposed a mode of action by diffusing away the cell membrane-stabilizing divalent ions, Ca2+ and Mg2+. This hypothesis was supported by our study that Ca2+ and Mg2+ supplementation in the assay medium causes up to 80% loss of bacterial killing efficacy and that the addition of divalent ion chelating ethylenediaminetetraacetic acid into the above assay medium leads to significant recovery of the bacterial killing efficacy. In addition to its potent bacteria...

Rapid and complete vascularization of the porous orbital implants after enucleation is vital for reducing postoperative complications, such as exposure and infection. In this study, the porous hydroxyapatite (pHA) scaffolds modified with the mesoporous bioactive glass with and without adding copper (MBG, Cu-MBG) were prepared by sol-gel technique and followed by evaporation induced self-assembly (EISA) process. The macro-/microstructure analysis of the modified scaffolds (i.e., MBG/pHA, Cu-MBG/pHA) showed highly interconnected macropores, and unique mesoporous structures in the pore wall with higher surface area. A primary angiogenic test in a panniculus carnosus muscle model in rabbit indicated that the Cu-MBG coating was significantly beneficial for the vascularization in the porous architecture of the scaffolds in the early stage. These results suggest that the Cu-MBG modification provides a simple and effective strategy to endow favorable biological performances with pHA implants and greater potential for future application in orbit reconstruction.

The development of smart theranostic systems with favourable biocompatibility, high loading efficiency, excellent circulation stability, potent anti-tumour activity, and multimodal diagnostic functionalities is of importance for future clinical application. The premature burst release and poor degradation kinetics indicative of polymer-based nanomedicines remain the major obstacles for clinical translation. Herein we prepare theranostic shell-crosslinked nanoparticles (SCNPs) using a β-cyclodextrin-based polyrotaxane (PDI-PCL-b-PEG-RGD⊃β-CD-NH2) to avoid premature drug leakage and achieve precisely controllable release, enhancing the maximum tolerated dose of the supramolecular nanomedicines. cRGDfK and perylene diimide are chosen as the stoppers of PDI-PCL-b-PEG-RGD⊃β-CD-NH2, endowing the resultant SCNPs with excellent integrin targeting ability, photothermal effect, and photoacoustic capability. In vivo anti-tumour studies demonstrate that drug-loaded SCNPs completely eliminate the subcutaneous tumours without recurrence after a single-dose injection combining chemotherapy and photothermal therapy. These supramolecular nanomedicines also exhibit excellent anti-tumour performance against orthotopic breast cancer and prevent lung metastasis with negligible systemic toxicity., Multifunctional nanomedicine platforms are highly promising for anticancer therapy. Here, the authors design polyrotaxane-based theranostic nanoparticles that combine targeted drug delivery with photothermal behaviour to exhibit potent anti-tumour effects in vivo.

Although great strides have been made in medical technology, low back/neck pain and intervertebral disc degeneration initiated from disc degenerative disease remains a clinical challenge. Within the field of regenerative medicine therapy, we have sought to improve the biomechanical transformation of spinal fusion procedures conducted using biodegradable porous implants. Specifically, we have focused on developing mechanically strong bioceramic cages for spinal fusion and functional recovery. Herein, we fabricated the akermanite (AKE) ceramic-based porous cages using low-melting bioactive glass (BG) and 3D printing technology. The osteogenic cell adhesion on the cages was evaluated in vitro, and the spinal fusion was tested in the intervertebral disc trauma model. The results indicated that incorporation of 15% or 30% BG into AKE (i.e., AKE/BG15 and AKE/BG30) could enhance the compressive strength of bioceramic cages by 2- or 5-fold higher than the pure AKE cages (AKE/BG0). In comparison with porous β-tricalcium phosphate cages, the surface of AKE/BG15 and AKE/BG30 cages greatly promoted the growth and alkaline phosphatase expression of osteogenic cells. Histological and biomechanical analysis showed that the AKE/BG15 and AKE/BG30 readily stimulated the new bone tissue growth and improved the spinal biomechanics recovery. In the AKE/BG15 and AKE/BG30 cage groups, 4-6 of the rabbits demonstrated a successful fusion. In contrast, only 0-1 of the initial seeded AKE/BG0 and tricalcium phosphate cages resulted in fusion at 12 weeks post-operatively. In summary, the akermanite-based cages showed an increased bone regenerative effect within an intervertebral disc trauma model, and thus, provided a promising candidate for improving spinal fusion surgery.

Excessive reactive oxygen species (ROS) generated after myocardial infarction (MI) result in the oxidative injury in myocardium. Implantation of antioxidant biomaterials, without the use of any type of drugs, is very appealing for clinical translation, leading to the great demand of novel biomaterials with high efficiency of ROS elimination. In this study, a segmented polyurethane (PFTU) with a high density of ROS-scavenging backbone units is synthesized by the reaction of poly(thioketal) dithiol (PTK) and poly(propylene fumarate) diol (PPF) (soft segments), thioketal diamine (chain extender), and 1,6-hexamethylene diisocyanate (HDI). Its chemical structure is verified by gel permeation chromatography (GPC), 1 H nuclear magnetic resonance (1 H NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The electrospun composite PFTU/gelatin (PFTU/Gt) fibrous patches show good antioxidation capacity and ROS-responsive degradation in vitro. Implantation of the PFTU/gelatin patches on the heart tissue surface in MI rats consistently decreases the ROS level, membrane peroxidation, and cell apoptosis at the earlier stage, which are not observed in the non-ROS-responsive polyurethane patch. Inflammation and fibrosis are also reduced in the PFTU/gelatin-treated hearts, resulting in the reduced left ventricular remodeling and better cardiac functions postimplantation for 28 d.

It is a significant challenge to regenerate full-thickness skin defects with sweat glands. Various skin substitutes have been developed to resolve this issue with minimal success. In this study, to yield a novel construct for in situ regeneration of sweat glands, the collagen-chitosan porous scaffold was combined with Lipofectamine 2000/pDNA-EGF complexes to obtain the gene-activated scaffold (GAS), which was then seeded with bone marrow-derived mesenchymal stem cells (BM-MSCs). The porous scaffold functionalized as a reservoir for the incorporated gene complexes which were released in a sustained manner. The seeded BM-MSCs were transfected in situ by the released complexes and specially differentiated into sweat gland cells in vitro under the induction of the expressed epidermal growth factor (EGF). Application in vivo of the GAS/BM-MSCs constructs on the full-thickness skin defects of SD rats confirmed that GAS/BM-MSCs could accelerate the wound healing process and induce the in situ regeneration of the full-thickness skin with sweat gland-like structures. Analyzed by immunohistochemical staining, RT-qPCR and Western-blotting, the levels of the major sweat gland markers such as carcino-embryonic antigen (CEA), cytokeratin 8 (CK8) and cytokeratin 14 (CK14) were all up-regulated, indicating that GAS/BM-MSCs can facilitate the regeneration of sweat glands-like structure in vivo.

// Xiao-Yi Chen 1, * , San-Zhong Xu 2, * , Xuan-Wei Wang 2, * , Xian-Yan Yang 3 , Liang Ma 3 , Lei Zhang 4 , Guo-Jing Yang 4 , Fan Yang 1 , Lin-Hong Wang 1 , Xin-Li Zhang 5 , Kang Ting 5 , Chang-You Gao 3 , Xiao-Zhou Mou 1 , Zhong-Ru Gou 3 and Hai Zou 6 1 Clinical Research Institute, Zhejiang Provincial People’s Hospital, Hangzhou 310014, China 2 The First Affiliated Hospital, School of Medicine of Zhejiang University, Hangzhou 310009, China 3 Zhejiang-California International Nanosystems Institute, Zhejiang University, Hangzhou 310058, China 4 Rui’an People’s Hospital & The 3rd Affiliated Hospital to Wenzhou Medical University, Rui’an 325005, China 5 Dental and Craniofacial Research Institute, School of Dentistry, University of California, Los Angeles, CA 90095, USA 6 Department of Cardiology, Zhejiang Provincial People’s Hospital, Hangzhou 310014, China * These authors have contributed equally to this work Correspondence to: Xiao-Zhou Mou, email: mouxz@zjheart.com Zhong-Ru Gou, email: zhrgou@zjheart.com Hai Zou, email: haire1993@163.com Keywords: mineral micronutrients, microparticles, osteogenic differentiation, rOMSCs, rMSCs Received: January 02, 2017 Accepted: March 06, 2017 Published: March 28, 2017 ABSTRACT Osteoporosis is a disease characterized by structural deterioration of bone tissue, leading to skeletal fragility with increased fracture risk. Calcium phosphates (CaPs) are widely used in bone tissue engineering strategies as they have similarities to bone apatite except for the absence of trace elements (TEs) in the CaPs. Bioactive glasses (BGs) have also been used successfully in clinic for craniomaxillofacial and dental applications during the last two decades due to their excellent potential for bonding with bone and inducing osteoblastic differentiation. In this study, we evaluated the osteogenic effects of the ionic dissolution products of the quaternary Si-Sr-Zn-Mg-codoped CaP (TEs-CaP) or 45S5 Bioglass® (45S5 BG), both as mixtures and separately, on rat bone marrow-derived mesenchymal stem cells (rOMSCs & rMSCs) from osteoporotic and normal animals, using an MTT test and Alizarin Red S staining. The materials enhanced cell proliferation and osteogenic differentiation, especially the combination of the BG and TEs-CaP. Analysis by quantitative PCR and ELISA indicated that the expression of osteogenic-specific genes and proteins were elevated. These investigations suggest that the TEs-CaP and 45S5 BG operate synergistically to create an extracellular environment that promotes proliferation and terminal osteogenic differentiation of both osteoporotic and normal rMSCs.

The adverse effect of airborne PM2.5 pollutes on human beings and the environment, most likely due to heavy metal leaching, has received extensive attention recently. It is urgently required to develop a simple and effective method to suppress the toxicity of PM2.5 pollutes. In this study, the heavy metal content of PM2.5 pollutes around Zhejiang university were firstly identified. Their cytotoxicity was confirmed, by inducing significantly enhanced intracellular reactive oxygen species level. Poly(N-isopropylacrylamide) (PNIPAM) submicron hydrogel particles with tunable crosslinking densities and thermo-responsive swelling/shrinking properties were then prepared by adjusting the crosslinking density. Anti-oxidant drug melatonin (MLT) was encapsulated into the obtained PNIPAM nanogel particles with the drug loading efficiency larger than 50%, achieving thermo-responsive drug release profile. The PNIPAM/MLT particles had a strong ability to reduce the cytotoxicity to Raw264.7 cells induced by the extractant of PM2.5 pollutes, as well as to suppress the intracellular reactive oxygen species (ROS) level and secretion of tumor necrosis factor alpha (TNF-α), especially when the cells were treated under 25°C for 3h after ingestion of the PNIPAM/MLT particles. This concept-proving study demonstrates the potential to use the thermo-responsive PNIPAM/MLT particles to suppress the toxicity of airborne PM2.5 pollutes, which is a paramount requirement for human health.

Migration and differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) is an important biological process in tissue regeneration. Nanostructured titanium materials are believed to play a fundamental role in dental and orthopedic applications. However, the protein adsorption on nanostructured titanium materials and its correlation with the subsequent cell behaviors have not been studied. In this work, the titania nanotube arrays with different tubular diameters ranging from 27.3 to 88.2 nm were fabricated by using an electrochemical etching method. The adsorbed amounts and types of cell adhesion-related proteins (such as fibronectin, vitronectin, and laminin) from serum were investigated, revealing that these proteins were preferred to bind onto the surface with nanotubes of a smaller diameter. Adhesion and migration of BMSCs were studied as a function of different nanotube diameters in the presence or absence of serum proteins. Compared with the nanotube surface with a larger tubular diameter (88.2 nm), the surface with a smaller one could better support BMSCs in terms of adhesion and spreading. The pre-adsorbed serum proteins significantly enhanced adhesion and migration abilities of BMSCs. However, the adequate interactions between cells and serum proteins on the nanotubes surface with smallest nanotubes in diameter weakened cell mobility. Arrangement of cytoskeleton and expressions of key genes and proteins were studied, revealing that the nanostructured surfaces and pre-adsorbed proteins jointly mediated the adhesion and migration of BMSCs.

Cell adhesive and other functional peptides (such as RGD, KRSR, YIGSR, VAPG, and BMP-2 peptides) are extensively studied and utilized in tissue engineering scaffolds and biomedical devices to modulate cell functions. Though PEG is frequently used as the antifouling layer, it is unclear how it affects the performance of functional peptides. By analyzing the impact of PEG at short (OEG4), medium (OEG8), and long chain length (PEG2K), we reveal that PEG chain length is critical and a medium-length PEG enables functional peptides to display their optimal and genuine functions in cell adhesion, migration, and differentiation by providing excellent antifouling to minimize background noise of unwanted cell adhesion and high enough surface density of functional peptides. Our result provides new avenues for maximizing the genuine functions of peptides. This study also provides a solution to prevent the heterogeneous and even divergent results caused by inappropriate choice of antifouling PEG and provides a general guidance in identifying new functional peptides.

Stimuli-responsive biomaterials supply a promising solution to adapt to the complex physiological environment for different biomedical applications. In this study, a dynamic UV-triggered pH-responsive biosurface was constructed on titania nanotubes (TNTs) by loading photoacid generators, diphenyliodonium chloride, into the nanotubes, and grafting 2,3-dimethyl maleic anhydride (DMMA)-modified hyperbranched poly(l-lysine) (HBPLL) onto the surface. The local acidity was dramatically enhanced by UV irradiation for only 30 s, leading to the dissociation of DMMA and thereby the transformation of surface chemistry from negatively charged caboxyl groups to positively charged amino groups. The TNTs-HBPLL-DMMA substrate could better promote proliferation and spreading of rat bone mesenchymal stem cells (rBMSCs) after UV irradiation. The osteogenic differentiation of rBMSCs was enhanced because of the charge reversal in combination with the titania-based substrates.

Reactive oxygen species (ROS) play an important role in the pathogenesis of numerous diseases including atherosclerosis, diabetes, inflammation and myocardial infarction (MI). In this study, a ROS-responsive biodegradable elastomeric polyurethane containing thioketal (PUTK) linkages was synthesized from polycaprolactone diol (PCL-diol ), 1,6-hexamethylene diisocyanate (HDI), and ROS-cleavable chain extender. The PUTK was electrospun into fibrous patches with the option to load glucocorticoid methylprednisolone (MP), which were then used to treat MI of rats in vivo. The fibrous patches exhibited suitable mechanical properties and high elasticity. The molecular weight of PUTK was decreased significantly after incubation in 1 mM H2O2 solution for 2 weeks due to the degradation of thioketal bonds on the polymer backbone. Both the PUTK and PUTK/MP fibrous patches showed good antioxidant property in an oxidative environment in vitro. Implantation of the ROS-responsive polyurethane patches in MI of rats in vivo could better protect cardiomyocytes from death in the earlier stage (24 h) than the non ROS-responsive ones. Implantation of the PUTK/MP fibrous patches for 28 days could effectively improve the reconstruction of cardiac functions including increased ejection fraction, decreased infarction size, and enhanced revascularization of the infarct myocardium.

Reactive oxygen species (ROS) have been considered the pivotal signaling molecules in many physiological processes, and are usually overproduced in various inflammatory tissues. Overproduction of ROS may disrupt cellular homeostasis, cause non-specific damage to critical components, and lead to a series of diseases. ROS are acknowledged as a type of emerging triggered event similar to acidic pH, overproduced enzymes, temperature and other specific stimuli found in pathological microenvironments. Recently, ROS-responsive biomaterials have been identified as a type of promising therapeutic substance to alleviate oxidative stress in tissue microenvironments, and for use as a vehicle triggered by inflammatory diseases to realize drug release under physiological oxidative microenvironments. In this review, we discuss mainly the mechanisms of ROS-responsive biomaterials with solubility switch and chemical degradation, and those ROS-responsive groups used in ROS-responsive biomaterials. The mechanism of ROS overproduction in pathophysiological conditions is introduced. The various applications of ROS-responsive biomaterials in tissue regeneration and disease therapy, such as cardiovascular diseases, osteoarthritis, chronic diabetic wounds, inflammatory bowel disease and other inflammatory diseases, are summarized.

Gold nanorods (GNRs) with longitudinal surface plasmon resonance (LSPR) peaks in second near-infrared (NIR-II) window have attracted a great amount of attention as photothermal transducer because of their inherently excellent photothermal transition efficiency, high biocompatibility and versatile surface functionalization. One key question for the application of these GNRs against tumors in vivo is which size/shape and surface ligand conjugation are promising for circulation and tumor targeting. In this study, we prepared a series of gold nanorods (GNRs) of similar aspect ratio and LSPR peaks, and thus similar photothermal transfer efficiency under irradiation of 980 nm laser, but with tunable size in width and length. The obtained GNRs were subjected to surface modification with PEG and tumor targeting ligand lactoferrin. With these tailor-designed GNRs in hand, we have the chance to study the impact of dimension and surface property of the GNRs on their internalization via tumor cells, photothermal cytotoxicity in vitro, blood circulation and tissue distribution pattern in vivo. As a result, the GNRs with medium size (70 nm in length and 11.5 nm in width) and surface PEG/LF modification (GNR70@PEG-LF) exhibit the fastest cell internalization via HepG2 cells and best photothermal outcome in vitro. The GNR70@PEG-LF also display long circulation time and the highest tumor accumulation in vivo, due to the synergetic effect of surface coating and dimension. Finally, tumor ablation ability of the GNRs under irradiation of 980 nm light were validated on mice xenograft model, suggesting their potential photothermal therapy against cancer in NIR-II window.

Conventional 3D porous scaffolds used as tarsal plate substitute may cause corneal irritation and conjunctival mucoid discharge, and even lead to blindness and cicatricial blepharon deformities. In this study, collagen/chitosan (Col/CS) sponges with thickness of 240 μm, 466 μm, and 724 μm were composited onto poly(propylene fumarate)-co-2-hydroxyethyl methacrylate (PPF–HEMA) polymer networks to obtain the corresponding biphasic scaffolds, which simulate the natural anatomy of posterior lamella of eyelid. These three scaffolds exhibited a porous structure with porosity of ∼90%, simulated elastic modulus, appropriate degradation rate and good biocompatibility. Composited with Col/CS sponge of difference thickness, the scaffolds induced different cellular behaviors such as proliferation, distribution and stratification, by regulating the mechanical properties cells sensed as effective modulus. In a rabbit tarso-conjunctival defect model, the grafted biphasic scaffolds promoted re-epithelization with functional regenerated conjunctiva. Hence, the biphasic composite scaffolds may be a promising substitute for tarso-conjunctival repair.

The nanodiamonds (NDs) have attracted much attention in biomedical applications due to their excellent magnetic and optical properties. However, comprehensive study of different surfacemodified NDs on toxicity and differentiation of mesenchymal stem cells are very deficient. In this study, three types of NDs, i.e., ND-COOH, ND-NH+₃ and ND-PEG were co-cultured with rat bone mesenchymal stem cells (MSCs) to assess their biosafety and effects on differentiation. In a dry state, they had a similar diameter of about 6-7 nm, and aggregated into ˜100 nm (hydrodynamic size) in cell culture medium. Co-culture with MSCs showed that the ND-COOH and ND-PEG had lower cytotoxicity than ND-NH+₃. Alkaline comet assay showed slight genotoxicity for all the NDs regardless of their surface coatings. The reactive oxygen species (ROS) test showed that the cytotoxicity and genotoxicity of NDs may be attributed to the NDs-mediated intracellular oxidative stress. All the NDs did not show significant impact on the osteogenic differentiation of MSCs, whereas the ND-COOH and ND-PEG slightly impaired the adipogenic differentiation. Taken together, these findings provide some momentous implications for the design of surface chemical structures of NDs for their applications in biological field.

The recruitment of endogenous mesenchymal stem cells (MSCs), as an alluring approach for in situ tissue regeneration, always accompanies with other types of cells. Therefore, it is of enormous value to bestow a substrate with the property of selective capture to MSCs. However, it was reported that when MSCs are cultured on a substrate with excessive affinity, their stemness diminished. Therefore, constructing a substrate with the balanced ability of selective capture and stemness maintenance becomes a big challenge. In this study, an Aptamer 19S (Apt19S)-modified substrate was fabricated by grafting Apt19S on a PEGylated glass substrate. The X-ray photoelectron spectroscopy results verified that the antifouling poly(ethylene glycol) (PEG) layer was created. Tracking by ellipsometry, the thicknesses of PEG layers were proved to increase with PEG concentration. The results of the quartz crystal microbalance also validated that the Apt19S densities could be modulated by the concentrations of the Apt19S solution. The results of the cell adhesion assay indicated that the modification of Apt19S caused a significant increase in the adhesion ratio and area of rBMSCs. Selective adhesion was confirmed by coculture of rBMSCs with macrophages and NIH3T3 cells, demonstrating that a higher proportion of rBMSCs adhered to the Apt19S-modified substrate. The results of specific capture were further confirmed by a flow model to simulate the body fluid flow. The comprehensive results of reverse transcription polymerase chain reaction, immunofluorescence staining, proliferation capacity, and differentiation assay showed that the stemness of rBMSCs was maintained better on a substrate with the appropriate Apt19S density. All of these results indicated that Apt19S modification is an effective strategy to endow a substrate with the specific capture ability of MSCs, and the balance between selective capture and stemness maintenance can be achieved by the precise regulation of the aptamer density.

Although the negative impacts of particulate matter (PM2.5) on human health have been well recognized, very few efforts have been paid to find new strategies to suppress the toxicity of PM2.5 both in vitro and in vivo. In this study, reactive oxygen species (ROS)-responsive nanoparticles made of poly(1,4-phenleneacetonedimethylene thioketal) (PPADT) were used to load immunosuppressant drug tacrolimus (FK506) with a drug loading efficiency of around 44%. The PPADT particles showed very good ROS-responsiveness and were degraded in an oxidation environment. By exhausting intracellular ROS, they could effectively suppress the toxicity of A549 lung epithelial cells and RAW264.7 macrophages induced by the PM2.5 particulates collected from three different regions in China. Moreover, the inflammatory response of PM2.5 could also be significantly suppressed, showing much better performance than the free FK506 drugs both in vitro and in vivo. This concept-proving research demonstrates the promising application for the ROS-sensitive drug release particles in dispelling the toxicity and suppressing the inflammation of PM2.5 pollutes, shedding a new light in the design and applications of stimuli-responsive systems in the bionanotechnology and healthcare fields.

Decellularization treatment has been widely used to decrease the potential immunogenicity and improve the anticalcification properties of bio-derived materials, which may be utilized as an alternative method for the preparation of bioprosthetic heart valves. However, the excessive decellularization treatments will deteriarate the properties of heart valves. Among the decellularizaton parameters, detergent concentration and processing time are considered as those of the most key factors. Therefore, it should be meaningful to balance the decellularization efficiency and properties of bioprosthetic heart valves by optimizing the detergent concentration and processing time. In this study, three groups of the decellularized heart valves treated by sodium deoxycholate (SD) with different concentration and processing time were investigated through histological, biochemical, and mechanical analysis. Similar decellularization efficiency can be concluded through histological staining, DNA and α-Gal quantification results. Extracellular matrix contents quantification and tensile test results revealed that there is no obvious difference among the three decellularized heart valves. in vitro cytotoxicity assay showed that the remnant detergent is not enough to cause cell death, which indicated that the decellularized porcine aortic heart valves may be suitable for further in vivo research. In conclusion, Triton X-100/SD may be a suitable protocol used for heart valves decellularization. And it is feasible to vary the detergent processing time by changing the detergent concentration without compromising the decellularization efficiency.

The biodegradable polymer microparticles with different surface morphology and chemical compositions may influence significantly the behaviors of cells, and thereby further the performance of tissue regeneration in vivo. In this study, multi-stage hierarchical textures of poly(D,L-lactic-co-glycolide) (PLGA)/PLGA-b -PEG (poly(ethylene glycol)) microspheres with a diameter as large as 50–100 μm are fabricated based on interfacial instability of an emulsion. The obtained fuzzy structures on the microspheres are sensitive to annealing, which are changed gradually to a smooth one after treatment at 37 °C for 6 d or 80 °C for 1 h. The surface microstructures that are chemically dominated by PEG can be stabilized against annealing by dopamine deposition. By the combination use of annealing and dopamine deposition, a series of microspheres with robust surface topologies are facilely prepared. The fuzzy microstructures and dopamine deposition show a synergetic role to enhance cell-material interaction, leading to a larger number of adherent bone marrow-derived mesenchymal stem cells (BMSCs), A549 and MC 3T3 cells. The fuzzy microspheres with dopamine deposition can significantly promote bone regeneration 12 w post surgery in vivo, as revealed by micro-CT, histological, western blotting and RT-PCR analyses.

Selective cell adhesion and migration, which mimics the natural biological events in vivo, is very important for the right repair of damaged tissues. In this study, glycosylated hyperbranched polymers (LA-HPMA) were synthesized, and were grafted on glass slide through dopamine deposition with different densities adjusted by co-grafting of poly(ethylene glycol) (PEG). The LA-HPMA and PEG molecular brushes were characterized by X-ray photoelectron spectroscopy (XPS), quartz crystal microbalance with dissipation (QCM-d) and ellipsometry. The adhesion of human hepatoma (HepG2) cells was promoted on the surface of a higher LA-HPMA density, and the migration rate was accelerated from 6.4μm/h on PEG surface to 12.7μm/h on 75% LA-HPMA surface. By contrast, the density and spreading area of mouse embryonic fibroblast (NIH3T3) cells were not significantly influenced by the LA-HPMA density, and the migration rate did not change significantly on all types of surfaces either. Therefore, the specific interactions of carbohydrate-protein can be used to modulate cell behaviors in vitro, for example the selective adhesion and migration of HepG2 cells.

Chirality is one of the most fascinating and ubiquitous features in nature, especially in biological systems. The effects of chiral surfaces, especially in combination with degradable materials of good biocompatibility, on stem cell behaviors has not yet been tackled. In this communication, the chiral monomers N-acryloyl-l(d)-valine (l(d)-AV) are synthesized and are polymerized to obtain chiral (l(d)-PAV-SH) oligomers, which are covalently immobilized onto electron-deficient poly(propylene fumarate) polyurethane (PPFU) via Michael addition. The PPFU-l-PAV can interact more strongly and actively with bone marrow stem cells (BMSCs) than PPFU-d-PAV, leading to a larger cell spreading area, faster migration velocity, and stronger osteodifferentiation tendency.

The poly(allylamine hydrochloride)/trisodium citrate aggregates were fabricated and further covalently crosslinked via the coupling reaction of carboxylic sites on trisodium citrate with the amine groups on polyamine, onto which poly-L-lysine and hyaluronic acid were sequentially assembled, forming stable microspheres. The pH sensitive dye and pH insensitive dye were further labeled to enable the microspheres with pH sensing property. Moreover, these microspheres could be specifically targeted to HeLa tumor cells, since hyaluronic acid can specifically recognize and bind to CD44, a receptor overexpressed on many tumor cells. Quantitative pH measurement by confocal laser scanning microscopy demonstrated that the microspheres were internalized into HeLa cells, and accumulated in acidic compartments. By contrast, only a few microspheres were adhered on the NIH 3T3 cells surface. The microspheres with combined pH sensing property and targeting ability can enhance the insight understanding of the targeted drug vehicles trafficking after cellular internalization.

The surface chemistry of nanoparticles (NPs) is one of the critical factors determining their cellular responses. In this study, the cytotoxicity and genotoxicity of copper oxide (CuO) NPs with a similar size but different surface chemistry to rat bone marrow mesenchymal stem cells (MSCs) were investigated. The morphology, size and surface charge of four types of CuO NPs, i.e., CuO-core, CuO-COOH, CuO-NH2 and CuO-PEG NPs, were characterized by TEM, dynamic light scattering (DLS) and zeta-potential measurement, respectively. All of the four CuO NPs had a negative surface charge around -10 mV and showed a similar tendency to form agglomerates with a size of -200 nm in cell culture environment. The cytotoxicity of CuO NPs to MSCs at various concentrations and incubation periods were firstly evaluated. The CuO NPs showed dose-dependent and time-dependent toxicity to MSCs, and their surface chemistry had influence on the toxicity to some extent too. The intracellular reactive oxygen species (ROS) level of MSCs was then quantified. Finally, the genotoxicity of the CuO NPs was studied by comet assay. The results suggest that the genotoxicity of CuO NPs was mainly dependent on NPs concentration, and was only slightly influenced by their surface chemistry. The osteogenic and adipogenic differentiation abilities of the MSCs exposed to different CuO NPs were studied by Alizarin Res S and Oil Red O staining. The preliminary results showed that the exposure to 10 μg/mL CuO NPs will, not lead to significant impact on the differentiation potential of the MSCs.

The graphene oxide (GO) has attracted tremendous attention in biomedical fields. In order to combine the unique physicochemical properties of GO nanosheets with topological structure of aligned nanofibrous scaffolds for nerve regeneration, the GO nanosheets were coated onto aligned and aminolyzed poly- l -lactide (PLLA) nanofibrous scaffolds. Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) revealed that the surface of aligned PLLA nanofibers after being coated with GO became rougher than those of the aligned PLLA and aminolyzed PLLA nanofibrous scaffolds. The GO nanosheets did not destroy the alignment of nanofibers. The characterizations of X-ray photoelectron spectroscopy (XPS) and water contact angle displayed that the aligned PLLA nanofibrous scaffolds were introduced with hydrophilic groups such as NH 2 , COOH, and OH after aminolysis and GO nanosheets coating, showing better hydrophilicity. The GO-coated and aligned PLLA nanofibrous scaffolds significantly promoted Schwann cells (SCs) proliferation with directed cytoskeleton along the nanofibers compared with the aligned PLLA and aminolyzed PLLA nanofibrous scaffolds. These scaffolds also greatly improved the proliferation of rat pheochromocytoma 12 (PC12) cells, and significantly promoted their differentiation and neurite growth along the nanofibrous alignment in the presence of nerve growth factor (NGF). This type of scaffolds with nanofibrous surface topography and GO nanosheets is expected to show better performance in nerve regeneration. Statement of Significance Recovery of damaged nerve functions remains a principal clinical challenge in spite of surgical intervention and entubulation. The use of aligned fibrous scaffolds provides suitable microenvironment for nerve cell attachment, proliferation and migration, enhancing the regeneration outcome of nerve tissue. Surface modification is generally required for the synthetic polymeric fibers by laminin, fibronectin and YIGSR peptides to stimulate specific cell functions and neurite outgrowth. Yet these proteins or peptides present the poor processibility, limited availability, and high cost, influencing their application in clinic. In this work, we combined GO nanosheets and topological structure of aligned nanofibrous scaffolds to direct cell migration, proliferation, and differentiation, and to induce neurite outgrowth for nerve regeneration. The GO coating improved several biomedical properties of the aligned PLLA nanofibrous scaffolds including surface roughness, hydrophilicity and promotion of cells/material interactions, which significantly promoted SCs growth and regulated cell orientation, and induced PC12 cells differentiation and neurite growth. The design of this type of structure is of both scientific and technical importance, and possesses broad interest in the fields of biomaterials, tissue engineering and regenerative medicine.

The adverse effects of metal-based nanoparticles on human beings and the environment have received extensive attention recently. It is urgently required to develop a simple and effective method to suppress the toxicity of metal-based nanomaterials. In this study, a hydrophobic antioxidant and a chelation agent curcumin (CUR) were encapsulated into bovine serum albumin (BSA) particles by a simple co-precipitation method, and followed by glutaraldehyde cross-linking. The CUR/BSA particles had an average size of 300 nm in diameter with a negatively charged surface and sustained curcumin release properties. The cellular uptake and cytotoxicity of CUR/BSA particles were followed on A549 cells, HepG2 cells and RAW264.7 cells. The CUR/BSA particles had higher intracellular accumulation and lower cytotoxicity compared with the free curcumin at the same drug concentration. The CUR/BSA particles could suppress the cytotoxicity generated by CuO nanoparticles as a result of decrease of both the intracellular reactive oxygen species (ROS) level and Cu(2+) concentration, while the free curcumin did not show any obvious detoxicating effect. The detoxicating effects of CUR/BSA particles were further studied in an intratracheal instillation model in vivo, demonstrating significant reduction of toxicity and inflammatory response in rat lungs induced by CuO nanoparticles. The concept-proving study demonstrates the potential of the CUR/BSA particles in suppressing cytotoxicity of metal-based nanomaterials, which is a paramount requirement for the safe application of nanotechnology.

The feasible fabrication of nerve guidance conduits (NGCs) with good biological performance is important for translation in clinics. In this study, poly(d,l-lactide-co-caprolactone) (PLCL) films loaded with various amounts (wt; 5%, 15%, 25%) of methylcobalamin (MeCbl) are prepared, and are further rolled and sutured to obtain MeCbl-loaded NGCs. The MeCbl can be released in a sustainable manner up to 21 days. The proliferation and elongation of Schwann cells, and the proliferation of Neuro2a cells are enhanced on these MeCbl-loaded films. The MeCbl-loaded NGCs are implanted into rats to induce the regeneration of 10 mm amputated sciatic nerve defects, showing the ability to facilitate the recovery of motor and sensory function, and to promote myelination in peripheral nerve regeneration. In particular, the 15% MeCbl-loaded PLCL conduit exhibits the most satisfactory recovery of sciatic nerves in rats with the largest diameter and thickest myelinated fibers.

It is well known that stealth coating effectively extends the circulation lifetime of nanomaterials in blood, which favors systemic delivery but also limits their cellular internalization and in turn prevents efficient tumor-targeting and accumulation. In this study, we address this dilemma by developing an enzyme-responsive zwitterionic stealth peptide coating capable of responding to matrix metalloproteinase-9 (MMP-9) which is overexpressed in tumor microenvironment. The peptide consists of a cell-penetrating Tat sequence, an MMP-9 cleavable sequence, and a zwitterionic antifouling sequence. Using this coating to protect photothermal gold nanorods (AuNRs), we found that responsive AuNRs showed both satisfactory systemic circulation lifetime and significantly enhanced cellular uptake in tumors, resulting in clearly improved photothermal therapeutic efficacy in mouse models. These results suggest that multifunctional peptide coated AuNRs sensitive to MMP-9 are promising nanomaterials, conferring both extended systemic circulation and enhanced tumor tissue accumulation, for more specific and efficient tumor therapy. STATEMENT OF SIGNIFICANCE: It is well known that stealth coating effectively extends the circulation lifetime of nanomaterials in blood, which favors systemic delivery but also limits their cellular internalization and in turn prevents efficient tumor-targeting and accumulation. In this study, we address this dilemma by developing an enzyme-responsive zwitterionic stealth peptide coating capable of responding to matrix metalloproteinase-9 (MMP-9) which is overexpressed in tumor microenvironment. The peptide consists of a cell-penetrating Tat sequence, an MMP-9 cleavable sequence, and a zwitterionic antifouling sequence. Using this coating to protect photothermal gold nanorods (AuNRs), we found that responsive AuNRs showed both satisfactory systemic circulation lifetime and significantly enhanced cellular uptake in tumors, resulting in clearly improved photothermal therapeutic efficacy in mouse models.

Bioactive stimulation and spatiotemporal evolution of porous scaffolds with time are crucial for bone regeneration rate in bone repair process. Granule-type bioceramic scaffolds have attracted significant interest in biomedical applications in recent years. However, the major limitation of such porous architecture is that the low initial porosity is disadvantageous for enhancing new bone tissue ingrowth. Here we reported that the yolk-shell-structured biphasic bioceramic granules with adjustable shell microstructures were favorable for controllable ion release in vitro, superior to the granules with the conventional homogenous hybrid structures. Also, we illustrated a significant difference in biodegradation of the granules in vivo, and especially the porous-shell granules exhibited appreciable new bone tissue ingrowth with time. The underlying fundamental mechanisms governing the new bone tissue ingrowth behavior of the yolk-shell granule scaffolds were elucidated based on microCT analyses and histological observation. It was underscored that during biodegradation in vivo, the highly bioactive ions in yolk layer were continuously released due to the porous structures of the sparingly dissolvable shell layer, thereby resulting in hollow shell and rapid new bone tissue ingrowth. Hence, these results demonstrate that the slight tailoring in microstructure and component distribution of biphasic composites is beneficial for adjusting the bone regeneration, and may help us to precisely control bone repair efficiency for a variety of clinical conditions.

Tissue regeneration involves versatile types of cells. The accumulation and disorganized behaviors of undesired cells impair the natural healing process, leading to uncontrolled immune response, restenosis, and/or fibrosis. Cell-selective surfaces and interfaces can have specific and positive effects on desired types of cells, allowing tissue regeneration with restored structures and functions. This review outlines the importance of surfaces and interfaces of biomaterials with cell-selective properties. The chemical and biological cues including peptides, antibodies, and other molecules, physical cues such as topography and elasticity, and physiological cues referring mainly to interactions between cells-cells and cell-chemokines or cytokines are effective modulators for achieving cell selectivity upon being applied into the design of biomaterials. Cell-selective biomaterials have also shown practical significance in tissue regeneration, in particular for endothelialization, nerve regeneration, capture of stem cells, and regeneration of tissues of multiple structures and functions.

The interplay of microstructures and biological cues is critical to regulate the behaviors of Schwann cells (SCs) in terms of cellular spatial arrangement and directional migration as well as neurite orientation for bridging the proximal and distal stumps of the injured peripheral nervous system. In this study, stripe micropatterns having ridges/grooves of width 20/20 and 20/40 μm were fabricated on the surface of maleimide-functionalized biodegradable poly(ester carbonate) (P(LLA-MTMC)) films by the polydimethylsiloxane mold-pressing method, respectively. The laminin-derived CQAASIKVAV peptides end-capped with an SH group were then grafted by the thiol-ene click reaction under mild conditions to obtain micropatterned and peptide-grafted films. SCs cultured on these films, especially on the 20/40-μm film, displayed faster and aligned adhesion as well as a larger number of elongated cells with a higher length-to-width (L/W) ratio along the stripe direction than those on the flat-pep film. The migration rate of SCs was significantly enhanced in parallel to the stripe direction with a large net displacement. The micropatterned and peptide-grafted films, especially the 20/40-μm film, could promote SC proliferation and nerve growth factor (NGF) secretion in a manner similar to that of the peptide-grafted planar film. Moreover, the neurites of rat pheochromocytoma 12 (PC12) cells sprouted along the ridges with a longer average length on the micropatterned and peptide-grafted films. The synergistic effect of physical patterns and biological cues was evaluated by considering the results of cell adhesion force; immunofluorescence staining of vinculin; fluorescence staining of F-actin and the nucleus; as well as gene expression of neural cadherin (NCAD), neurocan (NCAN), and myelin protein zero (P0). Statement of Significance The interplay of microstructures and biological cues is critical to regulate the behaviors of Schwann cells (SCs) and nerve cells, and thereby the regeneration of peripheral nerve system. In this study, the combined micropatterning and CQAASIKVAV grafting endowed the modified P(LLA-MTMC) films with both contact guidance and bioactive chemical cues to enhance cell proliferation, directional alignment and migration, longer net displacement and larger NGF secretion, and stronger neurite outgrowth of SCs and PC12 cells. Hence, the integration of physical micropatterns and bioactive molecules is an effective way to obtain featured biomaterials for the regeneration of nerves and other types of tissues.