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Konjac glucomannan (KGM) as an emerging natural polymer has attracted increasing interests owing to its film-forming properties, excellent gelation, non-toxic characteristics, strong adhesion, good biocompatibility, and easy biodegradability. Benefiting from these superior performances, KGM has been widely applied in the construction of multiple composite materials to further improve their intrinsic performances (e.g., mechanical strength and properties). Up to now, KGM-based composite materials have obtained widespread applications in diverse fields, especially in the field of biomedical. Therefore, a timely review of relevant research progresses is important for promoting the development of KGM-based composite materials. Innovatively, firstly, this review briefly introduced the structure properties and functions of KGMs based on the unique perspective of the biomedical field. Then, the latest advances on the preparation and properties of KGM-based composite materials (i.e., gels, microspheres, films, nanofibers, nanoparticles, etc.) were comprehensively summarized. Finally, the promising applications of KGM-based composite materials in the field of biomedical are comprehensively summarized and discussed, involving drug delivery, wound healing, tissue engineering, antibacterial, tumor treatment, etc. Impressively, the remaining challenges and opportunities in this promising field were put forward. This review can provide a reference for guiding and promoting the design and biomedical applications of KGM-based composites., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Electrical and dynamic stimulation are commonly employed to enhance the maturation of engineered cardiac tissue (ECT) derived from human induced pluripotent stem cells (iPSCs), reflecting the physiological environment of the heart. While electrical stimulation mimics natural bioelectrical signals and dynamic stimulation replicates mechanical forces, the combined effects of these stimuli on ECT maturation have not been thoroughly explored. We hypothesized that simultaneous electro-dynamic stimulation would enhance ECT maturation and function more effectively than either stimulus alone. Human iPSC-derived cardiovascular cells were co-cultured with Collagen I and Matrigel for 2 weeks, followed by a comparative analysis of four groups: no stimulation, dynamic stimulation, electrical stimulation, and simultaneous electro-dynamic stimulation. The functionality of ECTs was assessed by measuring contractile capacity and calcium indicators, and histological assessments examined structural maturation. Our results demonstrated that simultaneous electro-dynamic stimulation significantly increased the CM component, elevated TNNT2 mRNA expression levels, and enhanced calcium transient capacity. Additionally, ECTs subjected to simultaneous stimulation exhibited a positive force-frequency relationship in contractility and an elevation in peak calcium flux, indicative of advanced tissue maturation. Moreover, simultaneous stimulation promoted vascular network formation within the ECTs, suggesting improved structural organization. These findings underscore the importance of simultaneous stimulation for developing effective cardiac tissue engineering strategies., Competing Interests: Declaration of competing interest This research was supported by RIKEN BDR Organoid Project (to H.M.), and Grants-in-Aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture of Japan (to H.M.) (#23K24420). W.M., K.Murata and H.M. are inventors of engineered cardiac tissue-related patents. All authors declare that they have no financial conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Cartilage tissue engineering (CTE) with the help of engineered constructs has shown promise for the regeneration of hyaline cartilage, where fibrocartilage may also be formed due to the biomechanical loading resulting from the host weight and movement. Previous studies have primarily reported on hyaline cartilage formation in vitro and/or in small animals, while leaving the fibrocartilage formation undiscovered. In this paper, we, at the first time, present a comparison study on hyaline cartilage versus fibrocartilage formation in a large animal model of pig by using two constructs (namely hydrogel and hybrid ones) engineered by means of three-dimensional (3D) bioprinting. Both hydrogel and hybrid constructs were printed from the bioink of alginate (2.5%) and ATDC5 cells (chondrogenic cells at a cell density of 5 × 10 6 cells ml -1 ), with the difference in that in the hybrid construct, there was a polycaprolactone (PCL) strand printed between every two bioink strands, which were strategically designed to shield the force imposed on the cells within the bioink strands. Both hydrogel and hybrid constructs were implanted into the chondral defects created in the articular cartilage of weight-bearing portions of pig stifle joints; the cartilage formation was examined at one- and three-months post-implantation, respectively, by means of Safranin O, Trichrome, immunofluorescent staining, and synchrotron radiation-based (SR) inline phase contrast imaging microcomputed tomography (inline-PCI-CT). Glycosaminoglycan (GAG) and collagen type II (Col II) secretion were used to evaluate the hyaline cartilage formation, while collagen type I (Col I) was used to indicate fibrocartilage given that Col I is low in hyaline cartilage but high in fibrocartilage. Our results revealed that cartilage formation was enhanced over time in both hydrogel and hybrid constructs; particularly, the hydrogel construct exhibited more cartilage formation at both one- and three-months post-implantation, while hybrid constructs tended to have less fibrocartilage formed in a long time period. Also, the result from the inline-PCI-CT revealed that the inline-PCI-CT was able to provide not only the information seen in other histology images, but also high-resolution details of biomaterials and regenerating cartilage. This would represent a significant advance toward the non-invasive assessment of cartilage formation regeneration within large animal models and eventually in human patients., (Creative Commons Attribution license.)

The oral and maxillofacial region comprises a variety of organs made up of multiple soft and hard tissue, which are anatomically vulnerable to the pathogenic factors of trauma, inflammation, and cancer. The studies of this intricate entity have been long-termly challenged by a lack of versatile preclinical models. Recently, the advancements in the organoid industry have provided novel strategies to break through this dilemma. Here, we summarize the existing biological and engineering approaches that were employed to generate oral and maxillofacial organoids. Then, we detail the use of modified co-culture methods, such as cell cluster co-inoculation and air-liquid interface culture technology to reconstitute the vascular network and immune microenvironment in assembled organoids. We further retrospect the existing oral and maxillofacial assembled organoids and their potential to recapitulate the homeostasis in parental tissues such as tooth, salivary gland, and mucosa. Finally, we discuss how the next-generation organoids may benefit to regenerative and precision medicine for treatment of oral-maxillofacial illness., (© 2024. The Author(s).)

Tissue engineering is a promising approach for generating or repairing living tissues. The development of innovative biomaterials for tissue engineering has the potential to address the unmet clinical needs in certain applications. However, before these biomaterials can be used in clinical settings, they must undergo preclinical testing to ensure safety and performance. The chicken chorioallantoic membrane (CAM) assay is a preferred screening tool for studying biocompatibility, angiogenesis, and inflammation induced by biomaterials owing to ethical and economic considerations. This CAM-based platform increased the throughput of biomaterial testing for tissue engineering before in vivo testing. In this paper, we discuss the advantages of the CAM model. We also provided a step-by-step guide for implementing the CAM model in a research laboratory, along with tips and tricks for successfully running CAM assays. Finally, we present examples of biomaterials screened using CAM assays. CAM assay is a powerful in vivo model for assessing the angiogenic potential of tissue-engineered scaffolds. This guide provides a framework for conducting the assay, but specific experimental conditions should be optimized based on the scaffold material and the research question., (© 2024 The Author(s). Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals LLC.)

Objective: Utilizing biological scaffolds for cartilage tissue engineering is a promising tool for improving auricular reconstruction. Decellularized auricular scaffolds provide a means of regenerating cartilage for in vivo implantation, but identifying the ideal regenerative mix remains challenging., Methods: Human cadaver auricular cartilage was decellularized and recellularized with either auricular chondrocytes alone, auricular chondrocytes with adipose-derived stem cells, or both cells with platelet-rich plasma. Confirmation of decellularization and recellularization was done by hematoxylin and eosin staining. Extracellular matrix preservation and production were determined by Masson's trichrome, Alcian blue, and Verhoeff-van Gieson staining. Collagen II assessments were made using immunohistochemistry., Results: Decellularization of cadaver auricular cartilage was confirmed by the absence of cells, reduction in glycosaminoglycans, and the preservation of collagen and elastin. Recellularization was more efficient when chondrocytes were seeded with adipose-derived stem cells, which was enhanced by adding platelet-rich plasma. Coculture with platelet-rich plasma yielded better total collagen (56% increase) and glycosaminoglycan (47% increase) induction. Moreover, when platelet-rich plasma was added, collagen II induction was significantly increased (42%; P < 0.05)., Conclusion: We identified a regenerative protocol that included auricular chondrocytes, adipose-derived stem cells, and platelet-rich plasma, which stimulated chondrogenesis on decellularized auricular cartilage. This finding provides a model to explore cartilage formation and the potential for improving auricular and cartilage-based reconstruction., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Polysaccharide-based hydrogels have gained prominence due to their non-toxicity, biocompatibility, and structural adaptability for constructing tissue engineering scaffolds. Polysaccharide crosslinking is necessary for hydrogel stability in vivo. The periodate oxidation enables the modification of native polysaccharide characteristics for wound healing and tissue engineering applications. It produces dialdehydes, which are used to crosslink biocompatible amine-containing macromolecules such as chitosan, gelatin, adipic acid dihydrazide, silk fibroin, and peptides via imine/hydrazone linkages. Crosslinked oxidized ionic polysaccharide hydrogels have been studied for wound healing, cardiac and liver tissue engineering, bone, cartilage, corneal tissue regeneration, abdominal wall repair, nucleus pulposus regeneration, and osteoarthritis. Several modified hydrogel systems have been synthesized using antibiotics and inorganic substances to improve porosity, mechanical and viscoelastic properties, desired swelling propensity, and antibacterial efficacy. Thus, the injectable hydrogels provide a host-tissue-mimetic environment with high cell adhesion and viability, making them appropriate for scarless wound healing and tissue engineering applications. This review describes the oxidation procedure for alginate, hyaluronic acid, gellan gum, pectin, xanthan gum and chitosan, as well as the characteristics of the resulting materials. Furthermore, a critical review of scientific advances in wound healing and tissue engineering applications has been provided., Competing Interests: Declaration of competing interest The authors declare no potential conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Glycosaminoglycans (GAGs), also known as shape modules, are considered junctions that help define the shape of collagen matrix and further promote mineralization during osteogenesis. Many attempts have been made to immobilize GAGs on assembled collagen to modify the latter's surface state. However, it remains unclear how GAGs spontaneously identify collagen molecules during fibrillogenesis in vivo. Understanding the relationship between GAGs and collagen from both the bone physiology and materials science perspectives is of fundamental interest. Here, we introduced hyaluronic acid (HA, a main member of GAGs) during collagen self-assembly, in a process called modification cooperating with self-assembly (MCS). The molecular docking and morphological studies revealed that HA can help define collagen monomer deposition and thus promote fibrillogenesis through steric hindrance or by directly forming hydrogen bonds. Meanwhile, HA acts as a templating chaperone (TC) to increase the local mineral concentration within intrafibrillar channels but does not initiate nucleation, thus improving the crystallinity of formed apatite. The scaffolds synthesized through MCS model significantly improved the physicochemical stability and mechanical strength of collagen-based scaffolds. The optimized scaffolds promoted in-situ osteogenesis by stimulating the osteogenic differentiation of bone mesenchymal stem cells, either in an osteogenic medium, or after implantation into critical calvarial defects. This study provides novel insights towards evolving engineering scaffolds from inert supports to functional substitutes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Engineered matrices with aligned microarchitectures are pivotal in regulating the fibroblast-to-myofibroblast transition, a critical process for wound healing and scar reduction. However, developing a three-dimensional (3D) aligned matrix capable of effectively controlling this transition remains challenging. Herein, we developed a cell-adaptive hydrogel with highly oriented microporous structures, fabricated through bioprinting of thermo/ion/photo-crosslinked gelatin methacrylate/sodium alginate (GelMA/SA) incorporating shear-oriented polyethylene oxide (PEO) filler. The synergistic interactions among GelMA, PEO, and SA yield a homogeneous mixture conducive to the printing of biomimetic 3D constructs with anisotropic micropores. These anisotropic micropores, along with the biochemical cues provided by the GelMA/PEO/SA scaffolds, enhance the oriented spreading and organization of fibroblasts. The resultant spread and aligned cellular morphologies promote the transition of fibroblasts into myofibroblasts. By co-culturing human keratinocytes on the engineered dermal layer, we successfully create a bilayer skin construct, wherein the keratinocytes establish tight junctions accompanied by elevated expression of cytokeratin-14, while the fibroblasts display a highly spread morphology with increased fibronectin expression. The printed hydrogels accelerate full-thickness wound closure by establishing a bioactive microenvironment that mitigate inflammation and stimulate angiogenesis, myofibroblast transition, and extracellular matrix remodeling. This anisotropic hydrogel demonstrates substantial promise for applications in skin tissue engineering., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Due to the rise in cardiovascular disease and the problem of autologous transplant limitation, the emergence of 3D bioprinted blood vessels using natural polymer materials as ink is becoming increasingly important in the field of small-diameter artificial blood vessels (φ ≤ 6 mm). In this paper, gelatin was firstly adopted to explore alginate/chitosan composite hydrogel properties and solve the current issues of poor mechanical performance and suboptimal printability of small-diameter blood vessels, which indicated that the modification caused a 17.7 % increase in compressive strength and a 63.2 % enhancement in tensile properties. The material microstructure evaluation showed that the samples with gelatin(4 %) presented the excellent water absorption rate(>90 %) significantly increasing their porosities. A self-developed 3D bioprinter was utilized to clarify the controllable mechanism of small-diameter artificial blood vessel, which has superior performance and excellent printability. This study provides a new reference solution to the current challenges in the bio-ink performance and printability of small-diameter artificial blood vessels., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Kunpeng Jiao, Huanbao Liu, Tao zhang, Xiaoxi Li, Xiang Cheng, Guangxi Zhao, Guangming Zheng reports financial support, article publishing charges, equipment, drugs, or supplies, and writing assistance were provided by Shandong University of Technology. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Articular cartilage is a connective tissue with limited self-healing potential, frequently affected by trauma and degenerative changes, leading to osteoarthritis. Photobiomodulation paired with engineered tissue can improve cartilage's poor intrinsic healing and overcome its restricted self-regeneration. In this study, alginate-based scaffolds were fabricated with varying concentrations of CaCl₂ to achieve optimal mechanical, biocompatible, and biodegradable properties. The fluence-dependence of near-infrared (NIR) laser irradiation (830 nm) on chondrocyte viability and proliferation was investigated in a 2D environment across fluences (2.5-10 J/cm 2 ). Optimal conditions of 3 % w/v CaCl₂ and 5 J/cm 2 were identified to construct alginate scaffolds and promote chondrocyte growth in 2D and 3D cultures. Single PBM (830 nm, 5 J/cm 2 ) further exhibited a significant relative intensity of collagen type II immunostaining and stimulation of Col2a1 expression in 2D culture. Multiple PBM sessions (830 nm, 5 J/cm 2 ) significantly enhanced chondrocyte proliferation and glycosaminoglycan production in alginate scaffolds, with a protocol of one session every four days being the most effective. Scanning electron microscopy revealed PBM-induced secretory granule formation, corresponding to a significant increase in extracellular vesicle release. Consequently, integrating PBM and alginate-based scaffolds is a promising technique for accelerating and optimizing cartilage regeneration, with potential application in tissue engineering., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Engineered hydrogel patches have shown promising therapeutic effects in the treatment of myocardial infarction (MI), especially anisotropic patches that mimic the characteristics of native myocardium have attracted widespread attention. However, it remains a great challenge to develop cardiac patches with long-range and orderly electrical conduction based on an effective, mild, and rapid strategy. Here, a multifunctional anisotropic cardiac patch is presented based on microfluidic manipulation. The anisotropic alginate-gelatin methacrylate hydrogel patches are easily and rapidly prepared through microfluidic focusing, ion-photocrosslinking, and parallel packing processes. The fluid-based anisotropic realization process does not involve complex machining and strong field stimulation and is compatible with the loading of macromolecular biological agents. The anisotropic hydrogel patch can mimic the anisotropy of the myocardium and guide the directional polarization of cardiomyocytes. In animal model experiments, it also exhibits significant effects in inhibiting ventricular remodeling, fibrosis, and enhancing cardiac function recovery after MI. These comprehensive features make the multifunctional hydrogel patch a promising candidate for cardiac tissue repair and future provide a new paradigm for expanding microfluidic technology to solve tissue engineering challenges., (© 2024 Wiley‐VCH GmbH.)

To develop a biological bone tissue scaffold with uniform pore size and good cell adhesion was both challenging and imperative. We prepared modified cellulose nanocrystals (CNCs) dispersants (K-PCNCs) by ultrasound-assisted alkylation modification. Subsequently, nano-hydroxyapatite (HC-K) was synthesized using K-PCNCs as a dispersant and composited with polyvinyl alcohol (PVA) to prepare the scaffold using the ice template method. The results showed that the water contact angle and degree of substitution (135°, 1.53) of the K-PCNCs were highest when the ultrasound power was 450 W and the time was 2 h. The dispersion of K-PCNCs prepared under this condition was optimal. SEM showed that the pore distribution of the composite scaffolds was more homogeneous than the PVA scaffold. The porosity, equilibrium swelling rate, and mechanical properties of the composite scaffolds increased and then decreased with the increase of HC-K content, and reached the maximum values (56.1 %, 807.7 %, and 0.085 ± 0.004 MPa) at 9 % (w/w) of HC-K content. Cell experiments confirmed scaffold has good cytocompatibility and mineralization capacity. The ALP activity reached 1.71 ± 0.25 (ALP activity/mg protein). In conclusion, the scaffolds we developed have good biocompatibility and mechanical properties and have great potential in promoting bone defect repair., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Novel bioprinting technique offers strategy for building dense organ systems with complex multilayered vascular networks. Building on a technique called "sacrificial writing in functional tissue," researchers have developed immature organ systems capable of maintaining rudimentary function and maintaining viability owing to an intricate vascular network., (© 2024 International Center for Artificial Organs and Transplantation and Wiley Periodicals LLC.)

This study investigates the efficacy of a novel tissue-engineered scaffold for nerve repair and functional reconstruction following injury. Utilizing stable jet electrospinning, we fabricated aligned ultrafine fibers from dopamine and poly(L-lactic acid) (PLLA), further developing a biomimetic, oriented, and electroactive scaffold comprising poly(pyrrole) (PPy), polydopamine (PDA), and PLLA through dual in situ polymerizations. The scaffold demonstrated enhanced cell adhesion and reactive oxygen species (ROS) scavenging capabilities and promoted the differentiation of mesenchymal stem cells (MSCs) into Schwann-like cells, essential for nerve regeneration. In vivo assessments revealed significant peripheral nerve regeneration in 10 mm sciatic nerve defects in rats, with observations made 12 weeks post-transplantation. This included facilitated myelination and increased muscle density on the injured side, leading to improved motor function recovery. Our results suggest that the aligned PPy/PDA/PLLA fibrous scaffold offers a promising approach for promoting the differentiation of MSCs into Schwann-like cells conducive to nerve regeneration and represents a significant advancement in nerve repair technologies. This study provides a foundational basis for future research into tissue-engineered solutions for nerve damage, potentially impacting clinical strategies for nerve reconstruction., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Biomaterials play vital roles in regenerative medicine, specifically in tissue engineering applications. They promote angiogenesis and facilitate tissue creation and repair. The most difficult aspect of this field is acquiring smart biomaterials that possess qualities and functions that either surpass or are on par with those of synthetic products. The biocompatibility, biodegradability, film-forming capacity, and hydrophilic nature of the non-sulfated glycosaminoglycans (GAGs) (hyaluronic acid (HA) and chitosan (CS)) have attracted significant attention. In addition, CS and HA possess remarkable inherent biological capabilities, such as antimicrobial, antioxidant, and anti-inflammatory properties. This review provides a comprehensive overview of the recent progress made in designing and fabricating CS/HA-based hybrid materials for dermatology applications. Various formulations utilizing CS/HA have been developed, including hydrogels, microspheres, films, foams, membranes, and nanoparticles, based on the fabrication protocol (physical or chemical). Each formulation aims to enhance the materials' remarkable biological properties while also addressing their limited stability in water and mechanical strength. Additionally, this review gave a thorough outline of future suggestions for enhancing the mechanical strength of CS/HA wound dressings, along with methods to include biomolecules to make them more useful in skin biomedicine applications., Competing Interests: Declaration of competing interest I wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Osteochondral tissue engineering using layered scaffolds is a promising approach for treating osteochondral defects as an alternative to microfracture procedure, autologous chondrocyte implantation, and cartilage-bone grafting. The team previously investigated the chondrogenesis of mesenchymal stem cells (MSCs) on a polycaprolactone (PCL)/acetylated hyaluronic acid scaffold. The present study first focused on fabricating a novel osteoconductive scaffold utilizing bismuth-nanohydroxyapatite/reduced graphene oxide (Bi-nHAp/rGO) nanocomposite and electrospun PCL. The osteoconductive ability of the scaffold was investigated by evaluating the alkaline phosphatase (ALP) activity and the osteogenic genes expression in the adipose-derived MSCs. The expression of Runx2, collagen I, ALP, and osteocalcin as well as the result of ALP activity indicated the osteoconductive potential of the Bi-nHA-rGO/PCL scaffold. In the next step, a bilayer scaffold containing Bi-nHAp/rGO/PCL as an osteogenic layer and acetylated hyaluronic acid/PCL as a chondrogenic layer was prepared by the electrospinning technique and transplanted into osteochondral defects of rats. The chondrogenic and osteogenic markers corresponding to the surrounding tissues of the transplanted scaffold were surveyed 60 days later by real-time polymerase chain reaction (PCR) and immunohistochemistry methods. The results showed increased chondrogenic (Sox9 and collagen II) and osteogenic (osteocalcin and ALP) gene expression and augmented secretion of collagens II and X after transplantation. The results strongly support the efficacy of this constructed cell-free bilayer scaffold to induce osteochondral defect regeneration., (Copyright © 2024 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)

Microalgae are microorganisms that are rich in bioactive compounds, including pigments, proteins, lipids, and polysaccharides. These compounds can be utilized for a number of biomedical purposes, including drug delivery, wound healing, and tissue engineering. Nevertheless, encapsulating microalgae cells and microalgae bioactive metabolites is vital to protect them and prevent premature degradation. This also enables the development of intelligent controlled release strategies for the bioactive compounds. This review outlines the most employed encapsulation techniques for microalgae, with a particular focus on their biomedical applications. These include ionic gelation, oil-in-water emulsions, and spray drying. Such techniques have been widely explored, due to their ability to protect sensitive compounds from degradation, enhance their stability, extend their shelf life, mask undesirable tastes or odours, control the release of bioactive compounds, and enable targeted delivery to specific sites within the body or environment. Moreover, a patent landscape analysis is also provided, allowing an overview of the microalgae encapsulation technology development applied to a variety of fields, including pharmaceuticals, cosmetics, food, and agriculture., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

We have fabricated and characterized novel bioactive nanocomposite interpenetrating polymer network (IPN) scaffolds to treat bone defects by loading mesoporous silica nanoparticles (MSNs) into blends of Konjac glucomannan, polyvinyl alcohol, and polycaprolactone. By loading MSNs, we developed a porous nanocomposite scaffold with mechanical strengths comparable to cancellous bone. In vitro cell culture studies proved the cytocompatibility of the nanocomposite scaffolds. RT-PCR studies confirmed that these scaffolds significantly upregulated major osteogenic markers. The in vivo chick chorioallantoic membrane (CAM) assay confirmed the proangiogenic activity of the nanocomposite IPN scaffolds. In vivo studies were performed using Wistar rats to evaluate the scaffolds' compatibility, osteogenic activity, and proangiogenic properties. Liver and renal function tests confirmed that these scaffolds were nontoxic. X-ray and μ-CT results show that the bone defects treated with the nanocomposite scaffolds healed at a much faster rate compared to the untreated control and those treated with IPN scaffolds. H&E and Masson's trichrome staining showed angiogenesis near the newly formed bone and the presence of early-stage connective tissues, fibroblasts, and osteoblasts in the defect region at 8 weeks after surgery. Hence, these advantageous physicochemical and biological properties confirm that the nanocomposite IPN scaffolds are ideal for treating bone defects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bone implantation is one of the recognized and effective means of treating bone defects, but osteoporosis and bone tumor-related bone abnormalities have a series of problems such as susceptibility to infection, difficulty in healing, and poor therapeutic effect, which poses a great challenge to clinical medicine. Three-dimensional things may be printed using 3D printing. Researchers can feed materials through the printer layer by layer to create the desired shape for a 3D structure. It is widely employed in the healing of bone defects, and it is an improved form of additive manufacturing technology with prospective future applications. This review's objective is to provide an overview of the findings reports pertaining to 3D printing biopolymers in recent years, provide an overview of biopolymer materials and their composites with black phosphorus for 3D printing bone implants, and the characterization methods of composite materials are also summarized. In addition, summarizes 3D printing methods based on ink printing and laser printing, pointing out their special features and advantages, and provide a combination strategy of photothermal therapy and bone regeneration materials for black phosphorus-based materials. Finally, the associations between bone implant materials and immune cells, the bio-environment, as well as the 3D printing bone implants prospects are outlined., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Currently, the healing of large bone defects relies on invasive surgeries and the transplantation of autologous bone. As a less invasive treatment option, the provision of microenvironments that promote the regeneration of defective bones holds great promise. Here, we developed hyaluronic acid (HA)/gelatin (Ge) microgel-based scaffolds to guide bone regeneration. To enable the formation of microgels by enzymatic cross-linking in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H 2 O 2 ), we modified the polymers with tyramine (TA). Spectrophotometry and proton nuclear magnetic resonance ( 1 H NMR) spectroscopy analysis confirmed successful tyramine substitution on polymer backbones. To enable the formation of microgels by a water-in-oil emulsion approach, the HRP and H 2 O 2 concentrations were tuned to achieve the gelation in a few seconds. By varying the stirring speed from 600 to 1000 rpm, spherical microgels were produced with an average size of 116 ± 8.7 and 68 ± 4.7 μm, respectively. The results showed that microgels were injectable through needles and showed good biocompatibility with the cultured human osteosarcoma cell line (MG-63). HA/Ge-TA microgels served as a promising substrate for MG-63 cells since they improved the alkaline phosphatase activity and level of calcium deposition. In summary, the developed HA/Ge-TA microgels are promising injectable microgel-based scaffolds in bone tissue engineering., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Bone injury represents an urgent clinical problem, and implantable bioscaffolds offer suitable means for replacing and regenerating damaged tissues. This paper proposes an in-situ foaming printing method employing material extrusion additive manufacturing technology and physical foaming to prepared poly(lactic acid)/chitin nanocrystals (CHNCs) microporous composite scaffolds, featuring pore sizes ranging from 9 ± 5 μm. This method offers a novel strategy for the preparation of poly(lactic acid)-based scaffolds with good biocompatibility. Material characterization and mechanical property testing demonstrated that the in-situ foaming printed PLA scaffolds exhibited excellent foam printability, and the expansion ratio and compression properties of the scaffolds could be adjusted by modifying the CHNCs concentration and the printing speed, achieving a compression modulus between 39.2 MPa and 54.3 MPa. Furthermore, at equivalent foaming multiplicity (1.5-2.6 times), the compression modulus increased by nearly 100 % compared to previously reported PLA-based foam scaffolds. Importantly, the PLA/CHNCs scaffolds produced via in-situ foaming exhibited superior biocompatibility compared to directly printed PLA scaffolds. This PLA/CHNCs composite scaffold provides a promising approach to addressing and repairing bone defects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Polyphenol-functionalized biomaterials are significant in the field of bone tissue engineering (BTE) due to their antioxidant, anti-inflammatory, and osteoinductive properties. In this study, a gelatin (Gel)-based scaffold was functionalized with phloridzin (Ph), the primary polyphenol in apple by-products, to investigate its influence on physicochemical and morphological, properties of the scaffold for BTE application. A preliminary assessment of the biological properties of the functionalized scaffold was also undertaken. The Ph-functionalized scaffold (Gel/Ph) exhibited a porous structure with high porosity (71.3 ± 0.3 %), a pore size of 206.5 ± 1.7 μm, and a radical scavenging activity exceeding 70 %. This scaffold with Young's modulus of 10.8 MPa was determined to support cell proliferation and exhibited cytocompatibility with mesenchymal stem cells (MSCs). Incorporating hydroxyapatite nanoparticle (HA) in the Gel/Ph scaffold stimulated the osteogenic differentiation of key osteogenic genes, including Runx2, ALPL, COL1A1, and OSX ultimately promoting mineralization. This research highlights the promising potential of utilizing polyphenolic compounds derived from fruit waste to functionalize scaffolds for BTE applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Several advances in skin tissue engineering have been made to restore skin damage, facilitating wound healing. Bacterial cellulose (BC), a naturally occurring polymer, has gained attention as a potential material in wound healing due to its unique physical and biological properties. In recent years, with the advent of 3D bio-printing technology, new avenues have opened for fabricating customized wound dressings and scaffolds for tissue engineering purposes. The existing literature in this field mainly focuses on the ways of modifications of bacterial cellulose to make it printable. Still, the applicability of 3D printed scaffolds for wound healing needs to be explored more. This review article focuses on the current research on using 3D-printed BC for skin regeneration, including its production methods and physical and biological properties, making it a better choice than traditional dressings. Furthermore, it also highlights the limitations and future directions for using BC in wound healing and tissue engineering applications. This review provides a comprehensive and up-to-date exploration of the applications of 3D-printed BC in wound healing, drawing insights from pre-existing studies and emphasizing patient compliance, clinical outcomes, and economic viability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Inspired by the formation of natural abalone shells (AS) similar to calcium salt deposition in human orthodontics, AS is used as an emulsifier in the scaffold to solve the problem of coexistence of natural and synthetic polymers and promote new bone formation. In this study, AS-stabilized and reinforced carboxymethyl chitosan/collagen/PLGA porous bionic composite scaffolds (AS/CMCS/Col/PLGA) were fabricated through the emulsion polymerization and bionic hybrid technology. As the addition of AS increased from 0.75 to 3.0 wt%, homogeneous distribution of flower-like particles could be observed on the inner surface of the scaffold, and its mechanical properties were improved. Particularly, 3.0 wt% AS-doped scaffolds (S3 and C + S3) exhibited excellent inorganic mineral deposition and osteoblast proliferation and differentiation abilities in vitro. In a SD rat calvarial defect model, they effectively promoted new bone formation in the defect and accelerated expression of osteogenic-angiogenic related proteins (COLI, OCN, VEGF). By virtue of its combined merits including good mechanical properties, inducing mineralization crystallization and facilitating osteogenesis, the 3.0 wt% AS-doped scaffold promises to be employed as a novel bone repair material for bone tissue regeneration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The skin is a tissue constantly exposed to the risk of damage, such as cuts, burns, and genetic disorders. The standard treatment is autograft, but it can cause pain to the patient being extremely complex in patients suffering from burns on large body surfaces. Considering that there is a need to develop technologies for the repair of skin tissue like 3D bioprinting. Skin is a tissue that is approximately 1/16 of the total body weight and has three main layers: epidermis, dermis, and hypodermis. Therefore, there are several studies using cells, biomaterials, and bioprinting for skin regeneration. Here, we provide an overview of the structure and function of the epidermis, dermis, and hypodermis, and showed in the recent research in skin regeneration, the main cells used, biomaterials studied that provide initial support for these cells, allowing the growth and formation of the neotissue and general characteristics, advantages and disadvantages of each methodology and the landmarks in recent research in the 3D skin bioprinting., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Laryngeal cancer resections often require excision of portions of the larynx along with sacrifice of the ipsilateral recurrent laryngeal nerve (RLN). In such cases, there are no reconstructive options that reliably restore laryngeal function, rendering patients with severe functional impairment. To address this unmet clinical need, we extend our evaluation of a 3-implant mucosal, muscle, cartilage reconstruction approach aimed at promoting functional laryngeal restoration in a porcine hemilaryngectomy model with ipsilateral RLN transection., Methods: Six Yucatan mini-pigs underwent full-thickness hemilaryngectomies with RLN transection followed by transmural reconstruction using fabricated collagen polymeric mucosal, muscle, and cartilage replacements. To determine the effect of adding therapeutic cell populations, subsets of animals received collagen muscle implants containing motor-endplate-expressing muscle progenitor cells (MEEs) and/or collagen cartilage implants containing adipose stem cell (ASC)-derived chondrocyte-like cells. Acoustic vocalization and laryngeal electromyography (L-EMG) provided functional assessments and histopathological analysis with immunostaining was used to characterize the tissue response., Results: Five of six animals survived the 4-week postoperative period with weight gain, airway maintenance, and audible phonation. No tracheostomy or feeding tube was required. Gross and histological assessments of all animals revealed implant integration and regenerative remodeling of airway mucosa epithelium, muscle, and cartilage in the absence of a material-mediated foreign body reaction or biodegradation. Early voice and L-EMG data were suggestive of positive functional outcomes., Conclusion: Laryngeal reconstruction with collagen polymeric mucosa, muscle, and cartilage replacements may provide effective restoration of function after hemilaryngectomy with RLN transection. Future preclinical studies should focus on long-term functional outcomes., Level of Evidence: NA Laryngoscope, 134:4604-4613, 2024., (© 2024 The Author(s). The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc.)

Articular cartilage and subchondral bone defects have always been problematic because the osteochondral tissue plays a crucial role in the movement of the body and does not recover spontaneously. Here, an injectable hydrogel composed of oxidized sodium alginate/gelatin/chondroitin sulfate (OSAGC) was designed for the minimally invasive treatment and promotion of osteochondral regeneration. The OSAGC hydrogel had a double network based on dynamic covalent bonds, demonstrating commendable injectability and self-healing properties. Chondroitin sulfate was organically bound to the hydrogel network, retaining its own activity and gradually releasing during the degradation process as well as improving mechanical properties. The compressive strength could be increased up to 3 MPa by regulating the concentration of chondroitin sulphate and the oxidation level, and this mechanical stimulation could help repair injured tissue. The OSAGC hydrogel had a favourable affinity to articular cartilage and was able to release active ingredients in a sustained manner over 3 months. The OSAGC showed no cytotoxic effects. Results from animal studies demonstrated its capacity to regenerate new bone tissue in four weeks and new cartilage tissue in twelve weeks. The OSAGC hydrogel represented a promising approach to simplify bone surgery and repair damaged osteochondral tissue., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors confirm that the manuscript, or its contents in some other forms, has not been submitted or published previously elsewhere. All authors have seen and approved the manuscript and have contributed significantly for the paper., (Copyright © 2024. Published by Elsevier Ltd.)

Decellularized extracellular matrix (dECM) hydrogels loaded with adipose-derived stromal cells (ASC) or their conditioned medium (ASC CM) present a promising and versatile treatment approach for tissue vascularization and regeneration. These hydrogels are easy to produce, store, personalize, manipulate, and deliver to the target tissue. This literature review aimed to investigate the applications of dECM hydrogels with ASC or ASC CM for in vivo tissue vascularization. Fourteen experimental studies have been reviewed using vessel density as the primary outcome parameter for in vivo vascularization. The studies consistently reported an increased efficacy in augmenting angiogenesis by the ASC or ASC CM-loaded hydrogels compared to untreated controls. However, this systematic review shows the need to standardize procedures and characterization, particularly of the final administered product(s). The findings from these experimental studies highlight the potential of dECM hydrogel with ASC or ASC CM in novel tissue regeneration and regenerative medicine applications., Competing Interests: Declaration of competing interest The authors declare no conflict of interest. The funders had no role in the study's design, in the collection, analyses, interpretation of data, or the writing of the manuscript., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The intricate interaction of the scaffold's architecture/geometry and with the cells is essential for tissue engineering and regenerative medicine. Cells sense their surrounding dynamic cues such as biophysical, biomechanical, and biochemical, and respond to them differently. Numerous studies have recently explored and reported the effect of contact guidance by culturing various types of cells on different types of micropatterned substrates such as microgrooves, geometric (square and triangle) micropattern, microstrips, micropatterned nanofibers. Amongst all of these micropatterned polymeric substrates; electrospun nanofibers have been regarded as a suitable substrate as it mimics the native ECM architectures. Therefore, in the present study; stencil-assisted electrospun Grid-lined micropatterned PCL-Collagen nanofibers (GLMPCnfs) were fabricated and its influence on the alignment and differentiation of pre-osteoblast cells (MC3T3-E1) was investigated. The randomly orientated Non-patterned PCL-Collagen nanofibers (NPPCnfs) were used as control. The patterns were characterized for their geometrical features such as area and thickness of deposition using surface profiler and scanning electron microscopy. A 61 % decrease in the overall area of GLMPCnfs as compared to the stencil area demonstrated the potential of electrofocusing phenomenon in the process of patterning electrospun nanofibers into various micron-scale structures. The MC3T3-E1 cells were confined and aligned in the direction of GLMPCnfs as confirmed by a high cellular aspect ratio (AR = 5.41), lower cellular shape index (CSI = 0.243), and cytoskeletal reorganization assessed through the F-actin filament immunocytochemistry (ICC) imaging. The aligned cells along the GLMPCnfs exhibited elevated alkaline phosphatase activity and enhanced mineralization. Furthermore, the gene expression profiling revealed upregulation of key osteogenic markers, such as ALP, OCN, OPN, COL1A1, and osteocyte markers DMP1, and SOST. Consequently, the research highlights the impact of GLMPCnfs on the cellular behaviour that results to the pre-osteoblast differentiation and the potential for stimulant-free early osteogenesis. These results offer an extensive understanding and mechanistic insight into how scaffold topography can be modified to influence cellular responses for effective bone regeneration strategies., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Rajesh Vasita reports financial support was provided by Nanomission, DST, and Govt. of India project grant [No. SR/NM/NB-1079/2017(G)] and Science and Engineering Research Board, Department of Science and Technology, Govt. of India [TTR/2021/00120] that includes: funding grants. Rajesh vasita has patent: Prasoon Kumar, Rajesh Vasita, Bindiya Dhimmar, Kaushik Choudhary. Process of Fabrication of Polymer-based 3D multiscale structure for micro/nanosystem. Patent No. 377541, date of filing: 14/07/2019, Date of grant: 22/09/2021. Complete Patent filed on 30/04/2022. Granting country: India. pending to Rajesh vasita. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Stem cell-based therapies show promise for clinically addressing circumferential tracheal defects (CTD) through tissue engineering. However, creating a tissue-engineered tracheal tube possesses a healthy cartilage matrix and intact tube structure remains a challenge. A solution lies in the use of an injectable hydrogel with shape adaptability and chondrogenic capacity, serving as a practical and dependable platform for tubular tracheal cartilage regeneration. In this study, we developed an injectable hydrogel using modified natural polymers-hydrazide-grafted gelatin (Gelatin-ADH) and aldehyde-modified hyaluronic acid with sulfated groups (HA-CHO-SO 3 ) via Schiff Base interaction. Additionally, aldehyde-modified β-cyclodextrin (β-CD-CHO) was introduced into the network during hydrogel formation. The negative sulfated groups and hydrophobic cavities of β-cyclodextrin facilitated the efficient encapsulation and sustained release of transforming growth factor-β1 (TGF-β1) and kartogenin (KGN) within our hydrogel. This synergistically promoted the chondrogenesis of loaded bone marrow stem cells (BMSCs). Subsequently, we employed this TGF-β1, KGN, and BMSCs loaded hydrogel to form a cartilage ring. This ring was then assembled into an engineered tracheal cartilage tube using our previously reported ring-to-tube strategy. Our results demonstrated that the engineered tracheal cartilage tube effectively repaired CTD in a rabbit model. Hence, this study introduces a novel hydrogel with significant clinical application potential for tracheal tissue engineering., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Chitin and its deacetylated form, chitosan, have demonstrated remarkable versatility in the realm of biomaterials. Their exceptional biocompatibility, antibacterial properties, pro- and anticoagulant characteristics, robust antioxidant capacity, and anti-inflammatory potential make them highly sought-after in various applications. This review delves into the mechanisms underlying chitin/chitosan's biological activity and provides a comprehensive overview of their derivatives in fields such as tissue engineering, hemostasis, wound healing, drug delivery, and hemoperfusion. However, despite the wealth of studies on chitin/chitosan, there exists a notable trend of homogeneity in research, which could hinder the comprehensive development of these biomaterials. This review, taking a clinician's perspective, identifies current research gaps and medical challenges yet to be addressed, aiming to pave the way for a more sustainable future in chitin/chitosan research and application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

One of the critical factors that determines the biological properties of scaffolds is their structure. Due to the mechanical and structural discrepancies between the target bone and implants, the poor internal architecture design and difficulty in degradation of conventional bone implants may cause several adverse outcomes. To date, many scaffolds, such as 3-D printed sandwich structures, have been successfully developed for the repair of bone defects; however, the steps of these methods are complex and costly. Hydrogels have emerged as a unique scaffold material for repairing bone defects because of their good biocompatibility and excellent physicochemical properties. However, studies exploring bioinspired hydrogel scaffolds with hierarchical structures are scarce. More efforts are needed to incorporate bioinspired structures into hydrogel scaffolds to achieve optimal osteogenic properties. In this study, we developed a low-cost and easily available hydrogel matrix that mimicked the natural structure of the bone's porous sandwich to promote new bone growth and tissue integration. A comprehensive evaluation was conducted on the microstructure, swelling rate, and mechanical properties of this hydrogel. Furthermore, a 3D finite element analysis was employed to model the structure-property relationship. The results indicate that the sandwich-structured hydrogel is a promising scaffold material for bone injury repair, exhibiting enhanced compressive stress, elastic modulus, energy storage modulus, and superior force transmission., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Tissue engineering can provide in vitro models for drug testing, disease modeling, and perhaps someday, tissue/organ replacements. For building 3D heart tissue, the alignment of cardiac cells or cardiomyocytes (CMs) is important in generating a synchronously contracting tissue. To that end, researchers have generated several fabrication methods for building heart tissue, but direct comparisons of pros and cons using the same cell source is lacking. Here, we derived cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs) and compare the assembly of these cells using three fabrication methods: cardiospheres, muscle rings, and muscle strips. All three protocols successfully generated compacted tissue comprised of hiPSC-derived CMs stable for at least 2 weeks. The percentage of aligned cells was greatest in the muscle strip (55%) and the muscle ring (50%) compared with the relatively unaligned cardiospheres (35%). The iPSC-derived CMs within the muscle strip also exhibited the greatest elongation, with elongation factor at 2.0 compared with 1.5 for the muscle ring and 1.2 for the cardiospheres. This is the first direct comparison of various fabrication techniques using the same cell source., (© 2024 The Authors. Journal of Biomedical Materials Research Part A published by Wiley Periodicals LLC.)

Chemically defined, suspension culture conditions are a key requirement in realizing clinical translation of engineered cardiac tissues (ECTs). Building on our previous work producing functional ECT microspheres through differentiation of biomaterial encapsulated human induced pluripotent stem cells (hiPSCs), here we establish the ability to use chemically defined culture conditions, including stem cell media (E8) and cardiac differentiation media (chemically defined differentiation media with three components, CDM3). A custom microfluidic cell encapsulation system was used to encapsulate hiPSCs at a range of initial cell concentrations and diameters in the hybrid biomaterial, poly(ethylene glycol)-fibrinogen (PF), for the formation of highly spherical and uniform ECT microspheres for subsequent cardiac differentiation. Initial microsphere diameter could be tightly controlled, and microspheres could be produced with an initial diameter between 400 and 800 µm. Three days after encapsulation, cardiac differentiation was initiated through small molecule modulation of Wnt signaling in CDM3. Cardiac differentiation occurred resulting in in situ ECT formation; results showed that this differentiation protocol could be used to achieve cardiomyocyte (CM) contents greater than 90%, although there was relatively high variability in CM content and yield between differentiation batches. Spontaneous contraction of ECT microspheres initiated between Days 7 and 10 of differentiation and ECT microspheres responded to electrical pacing up to 1.5 Hz. Resulting CMs had well-defined sarcomeres and the gap junction protein, connexin 43, and had appropriate temporal changes in gene expression. In summary, this study demonstrated the proof-of-concept to produce functional ECT microspheres with chemically defined media in suspension culture in combination with biomaterial support of microsphere encapsulated hiPSCs., (© 2024 Wiley Periodicals LLC.)

Regarding its structural and mechanical adaptability to bone defects, 3D printed (3DP) Ti6Al4V scaffolds are widely used in orthopedics now, purposed to restore the function and mechanical stability of impaired bone. In scaffold fabrication, surface modification is acknowledged as a reliable strategy to enhance the interface interaction between 3DP Ti6Al4V scaffold and bone. Despite its advantage in bone-Ti6Al4V bonding improvement, surface modification lacks the ability to induce bone in-growth efficiently as expected. As an attempt to overcome this challenge, in the current work the inner voids of 3DP Ti6Al4V scaffold were occupied by a gelatin/chitosan porous matrix, purposed to act as a platform for guiding bone ingrowth. Firstly, the gelatin/chitosan matrix was prepared via freeze-drying using genipin as a crosslinker, resulting in a trabecular bone-like interconnected porous network characterized with a gelatin/chitosan ratio dependent swelling capability, degradation and model anti-bacterial drug release behavior. Besides of that, gelatin in the matrix was witnessed to accelerate biomineralization in simulated body fluid. Secondly, a formulated gelatin/chitosan matrix was embedded into 3DP Ti6Al4V scaffold to generate a composite scaffold capable of inducing bone in-growth. The followed studies showed gelatin/chitosan matrix can endow the scaffold with good biological and sustained drug release properties, along with minimal change to the compressive strength of the scaffold. The in vivo experiment results revealed that after 4 weeks of implantation, more new bone formation was witnessed in the inner structure of the composite scaffold than the 3DP Ti6Al4V scaffold, with the average bone volume fraction (BV/TV) value increased from 24.09 % to 46.08 %, the average trabecular bone thickness (Tb. Th) value increased from 0.118 mm to 0.278 mm. Therefore, it was confirmed an inner matrix in 3DP Ti6Al4V scaffold played an essential role in guiding bone in-growth., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Fibroin, the main structural protein of Bombyx mori silk, is known for its mechanical properties, its biocompatibility and degradation characteristics in vivo. Various studies investigate its uses as cell carrier and/or material for surgical implants. Multiple protocols have been established to isolate fibroin from silk fibers and to produce scaffolds and films from fibroin solution. There is only limited literature available on how fibroin scaffolds manufactured by different methods compare to each other in terms of performance as cell carriers. This study compares the behaviour of human adipose derived stromal cells (ADSC) seeded on fibroin scaffolds produced by (i) salt-leaching and (ii) freeze-thawing. One type of freeze-thawing scaffold (poresize ≪ 315 μm) and three types of salt-leaching scaffolds (poresize ranging from 315 μm to 1000 μm) were used for this comparison. Measuring the DNA concentration on the seeded scaffolds as well as the seeded cells metabolic activity, we were able to determine freeze-thawed scaffolds to be superior for cell-seeding. ADSC seeded on salt-leaching scaffolds displayed a stronger downregulation of serum deprivation response gene than cells seeded on freeze-thaw scaffolds. In sum, our findings show that salt-leaching scaffolds offering different pore sizes differed much less among each other than salt-leaching from freeze-thawing scaffolds in terms of cell accommodation. Our work underlines the importance of physicochemical scaffold properties directly linked to different manufacturing methods and their influence on the cell seeding capacity of silk fibroin based carriers., Competing Interests: Declaration of competing interest Alexander Kopp reports a relationship with Fibrothelium GmbH that includes: board membership and employment. Alexander Drinic reports a relationship with Fibrothelium GmbH that includes: employment. Benedetta Isella reports a relationship with Fibrothelium GmbH that includes: employment. Alissa Heim reports a relationship with Fibrothelium GmbH that includes: employment. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Bacterial cellulose (BC) is gathering increased attention due to its remarkable physico-chemical features. The high biocompatibility, hydrophilicity, and mechanical and thermal stability endorse BC as a suitable candidate for biomedical applications. Nonetheless, exploiting BC for tissue regeneration demands three-dimensional, intricately shaped implants, a highly ambitious endeavor. This challenge is addressed here by growing BC within a sacrificial viscoelastic medium consisting of an agarose gel cast inside polydimethylsiloxane (PDMS) molds imprinted with the features of the desired implant. BC produced with and without agarose has been compared through SEM, TGA, FTIR, and XRD, probing the mild impact of the agarose on the BC properties. As a first proof of concept, a PDMS mold shaped as a doll's ear was used to produce a BC perfect replica, even for the smallest features. The second trial comprised a doll face imprinted on a PDMS mold. In that case, the BC production included consecutive deactivation and activation of the aerial oxygen stream. The resulting BC face clone fitted perfectly and conformally with the template doll face, while its rheological properties were comparable to those of collagen. This streamlining concept conveys to the biosynthesized nanocelluloses broader opportunities for more advanced prosthetics and soft tissue engineering uses., Competing Interests: Declaration of competing interest The authors declare that they have no competing financial or personal interests that may influence the work reported in this study., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Peptide-based self-assembly has been used to produce a wide range of nanostructures. While most of these systems involve self-assembly of α-peptides, more recently β-peptides have also been shown to undergo supramolecular self-assembly, and have been used to produce materials for applications in tissue engineering, cell culture and drug delivery. In order to engineer new materials with specific structure and function, theoretical molecular modelling can provide significant insights into the collective balance of non-covalent interactions that drive the self-assembly and determine the structure of the resultant supramolecular materials under different conditions. However, this approach has only recently become feasible for peptide-based self-assembled nanomaterials, particularly those that incorporate non α-amino acids. This perspective provides an overview of the challenges associated with computational modelling of the self-assembly of β-peptides and the recent success using a combination of experimental and computational techniques to provide insights into the self-assembly mechanisms and fully atomistic models of these new biocompatible materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Bone regeneration often fails due to implants/grafts lacking vascular supply, causing necrotic tissue and poor integration. Microsurgical techniques are used to overcome this issue, allowing the graft to anastomose. These techniques have limitations, including severe patient morbidity and current research focuses on stimulating angiogenesis in situ using growth factors, presenting limitations, such as a lack of control and increased costs. Non-biological stimuli are necessary to promote angiogenesis for successful bone constructs. Recent studies have reported that bioactive glass dissolution products, such as calcium-releasing nanoparticles, stimulate hMSCs to promote angiogenesis and new vasculature. Moreover, the effect of 3D microporosity has also been reported to be important for vascularisation in vivo. Therefore, we used room-temperature extrusion 3D printing with polylactic acid (PLA) and calcium phosphate (CaP) based glass scaffolds, focusing on geometry and solvent displacement for scaffold recovery. Combining both methods enabled reproducible control of 3D structure, porosity, and surface topography. Scaffolds maintained calcium ion release at physiological levels and supported human mesenchymal stem cell proliferation. Scaffolds stimulated the secretion of vascular endothelial growth factor (VEGF) after 3 days of culture. Subcutaneous implantation in vivo indicated good scaffold integration and blood vessel infiltration as early as one week after. PLA-CaP scaffolds showed increased vessel maturation 4 weeks after implantation without vascular regression. Results show PLA/CaP-based glass scaffolds, made via controlled 3D printing, support angiogenesis and vessel maturation, promising improved vascularization for bone regeneration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Biodegradable polymer microspheres in bone tissue engineering have become appealing as their non-invasive advantages in irregular damage bone repair. However, current microspheres used in BTE still lack sufficient osteogenic capacity to induce effective bone regeneration. In this study, we developed osteogenic composite microspheres concurrently loaded with magnesium oxide (MgO) and zinc oxide (ZnO), both of which are osteogenic active substances, using a facile and scalable emulsification method. The osteogenic composite microspheres exhibited a sequential yet complementary release profile characterized by a rapid release of Mg 2+ and a gradual release of Zn 2+ in a physiological environment, thereby maintaining the concentration of bioactive ions at a sustained high level. As a result, the combination of Mg 2+ and Zn 2+ in the composite microspheres led to a synergistic enhancement in biomimetic mineralization and the upregulation in the expression of osteogenic-related genes and proteins at the cellular level. Through a critical-sized calvarial rate defect model, the osteogenic composite microspheres were demonstrated to have strong osteogenic ability to promote new bone formation via ultrasonic imaging, histological and immunohistochemical evaluations. In sum, these osteogenic composite microspheres as microcarriers of Mg 2+ and Zn 2+ have great potential in the delivery of therapeutic ions for treating bone defects., Competing Interests: Declaration of competing interest The authors declared no financial or personal conflict of interest that could affect their objectivity or inappropriately influence their actions., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study presents new injectable hydrogels based on hyaluronic acid and collagen type II that mimic the polysaccharide-protein structure of natural cartilage. After collagen isolation from chicken sternal cartilage, tyramine-grafted hyaluronic acid and collagen type II (HA-Tyr and COL-II-Tyr) were synthesized. Hybrid hydrogels were prepared with different ratios of HA-Tyr/COL-II-Tyr using horseradish peroxidase and noncytotoxic concentrations of hydrogen peroxide to encapsulate human bone marrow-derived mesenchymal stromal cells (hBM-MSCs). The findings showed that a higher HA-Tyr content resulted in a higher storage modulus and a lower hydrogel shrinkage, resulting in hydrogel swelling. Incorporating COL-II-Tyr into HA-Tyr hydrogels induced a more favorable microenvironment for hBM-MSCs chondrogenic differentiation. Compared to HA-Tyr alone, the hybrid HA-Tyr/COL-II-Tyr hydrogel promoted enhanced chondrocyte adhesion, spreading, proliferation, and upregulation of cartilage-related gene expression. These results highlight the promising potential of injectable HA-Tyr/COL-II-Tyr hybrid hydrogels to deliver cells for cartilage regeneration., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Mohammad J. Abdekhodaie reports financial support was provided by Council for Development of Stem Cell Sciences and Technologies. Mohammad J. Abdekhodaie reports financial support was provided by Iran National Science Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

A regenerative peripheral nerve interface (RPNI) offers a therapeutic solution for nerve injury through reconstruction of the target muscle. However, implanting a transected peripheral nerve into an autologous skeletal muscle graft in RPNI causes donor-site morbidity, highlighting the need for tissue-engineered skeletal muscle constructs. Here, an engineered regenerative isolated peripheral nerve interface (eRIPEN) is developed using 3D skeletal cell printing combined with direct electrospinning to create a nanofiber membrane envelop for host nerve implantation. In this in vivo study, after over 8 months of RPNI surgery, the eRIPEN exhibits a minimum Feret diameter of 15-20 µm with a cross-sectional area of 100-500 µm 2 , representing the largest distribution of myofibers. Furthermore, neuromuscular junction formation and muscle contraction with a force of ≈28 N are observed. Notably, the decreased hypersensitivity to mechanical/thermal stimuli and an improved tibial functional index from -77 to -56 are found in the eRIPEN group. The present novel concept of eRIPEN paves the way for the utilization and application of tissue-engineered constructs in RPNI, ultimately realizing neuroprosthesis control through synaptic connections., (© 2024 Wiley‐VCH GmbH.)

Objectives: Engineered Heart Tissue (EHT) is a promising tool to repair heart muscle defects and can additionally be used for drug testing. Due to the absence of an in vitro vascularization, EHT geometry crucially impacts nutrient and oxygen supply by diffusion capacity. We analyzed cardiomyocyte survival in different EHT geometries., Methods: Different geometries with varying surface-area-to-volume-ratios were calculated (structure A (Ring) AS/V = 58.47 mm 2 /440 μL 3 , structure B (Infinity) 25.86 mm 2 /440 μL 3 ). EHTs were generated from hiPSC-derived cardiomyocytes (4 × 10 6 ) and a fibrin/thrombin hydrogel. Cell viability was evaluated by RT-PCR, cytometric studies, and Bioluminescence imaging., Results: Using 3D-printed casting molds, spontaneously beating EHTs can be generated in various geometric forms. At day 7, the RT-PCR analyses showed a significantly higher Troponin-T value in ring EHTs, compared to infinity EHTs. In cytometric studies, we evaluated 15% more Troponin-T positive cells in ring (73% ± 12%), compared to infinity EHTs (58% ± 11%, p = 0.04). BLI visualized significantly higher cell survival in ring EHTs (ROI = A: 1.14 × 10 6 p/s and B: 8.47 × 10 5 p/s, p < 0.001) compared to infinity EHTs during longitudinal cultivation process., Conclusion: Use of 3D-printing allows the creation of EHTs in all desired geometric shapes. The geometry with an optimized surface-area-to-volume-ratio (ring EHT) demonstrated a significantly higher cell survival measured by RT-PCR, Bioluminescence imaging, and cytometric studies using FACS analysis., (© 2024 The Author(s). Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

With the development in the field of biomaterials, research on alternative biocompatible materials has been initiated, and alginate in polysaccharides has become one of the research hotspots due to its advantages of biocompatibility, biodegradability and low cost. In recent years, with the further understanding of microscopic molecular structure and properties of alginate, various physicochemical methods of cross-linking strategies, as well as organic and inorganic materials, have led to the development of different properties of alginate hydrogels for greatly expanded applications. In view of the potential application prospects of alginate-based hydrogels, this paper reviews the properties and preparation of alginate-based hydrogels and their major achievements in delivery carrier, dressings, tissue engineering and other applications are also summarized. In addition, the combination of alginate-based hydrogel and new technology such as 3D printing are also involved, which will contribute to further research and exploration., Competing Interests: Declaration of competing interest No conflict of interest exits in the submission of this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study focuses on designing and evaluating scaffolds with essential properties for bone regeneration, such as biocompatibility, macroporous geometry, mechanical strength, and magnetic responsiveness. The scaffolds are made using 3D printing with acrylic resin and iron oxides synthesized through solution combustion. Utilizing triply periodic minimal surfaces (TPMS) geometry and mask stereolithography (MSLA) printing, the scaffolds achieve precise geometrical features. The mechanical properties are enhanced through resin curing, and magnetite particles from synthesized nanoparticles and alluvial magnetite are added for magnetic properties. The scaffolds show a balance between stiffness, porosity, and magnetic responsiveness, with maximum compression strength between 4.8 and 9.2 MPa and Young's modulus between 58 and 174 MPa. Magnetic properties such as magnetic coercivity, remanence, and saturation are measured, with the best results from scaffolds containing synthetic iron oxides at 1% weight. The viscosity of the mixtures used for printing is between 350 and 380 mPas, and contact angles between 90° and 110° are achieved. Biocompatibility tests indicate the potential for clinical trials, though further research is needed to understand the impact of magnetic properties on cellular interactions and optimize scaffold design for specific applications. This integrated approach offers a promising avenue for the development of advanced materials capable of promoting enhanced bone regeneration., (© 2024 Wiley‐VCH GmbH.)

The current study was a preliminary evaluation of the feasibility and biologic features of three-dimensionally bio-printed tissue-engineered (3D bio-printed) vascular grafts comprising dermal fibroblast spheroids for venous replacement in rats and swine. The scaffold-free tubular tissue was made by the 3D bio-printer with normal human dermal fibroblasts. The tubular tissues were implanted into the infrarenal inferior vena cava of 4 male F344-rnu/rnu athymic nude rats and the short-term patency and histologic features were analyzed. A larger 3D bio-printed swine dermal fibroblast-derived prototype of tubular tissue was implanted into the right jugular vein of a swine and patency was evaluated at 4 weeks. The short-term patency rate was 100%. Immunohistochemistry analysis showed von Willebrand factor positivity on day 2, with more limited positivity observed on the luminal surface on day 5. Although the cross-sectional area of the wall differed significantly between preimplantation and days 2 and 5, suggesting swelling of the tubular tissue wall (both p < 0.01), the luminal diameter of the tubular tissues was not significantly altered during this period. The 3D bio-printed scaffold-free tubular tissues using human dermal or swine fibroblast spheroids may produce better tissue-engineered vascular grafts for venous replacement in rats or swine., Competing Interests: Disclosure: The authors have no conflicts of interest to report., (Copyright © ASAIO 2024.)

Introduction: The electro-actuated shape memory polymer scaffold has gained increasing attentions on the utilization of minimally invasive surgery for bone defect repair, which requires to construct an efficient conductive network to accomplish electrical-to-thermal conversion from conductive fillers to the entire matrix evenly., Objectives: In this study, multiwall carbon nanotube (MWCNT) was convective self-assembled on the ZnO tetrapod (t-ZnO) template, where MWCNT was controlled to disperse uniformly and regulated to contact with each other effectively due to the immersion capillary force during the evaporation loss of the convective self-assembly process, leading to an interwoven layer on the t-ZnO surface., Methods: The prepared t-ZnO@MWCNT assembly was embedded in the poly(L-lactic acid)/thermoplastic polyurethane (PLLA/TPU) scaffold fabricated via selective laser sintering to construct a 3D conductive MWCNT network for improving the electro-actuated shape memory properties., Results: It was observed that the interconnected MWCNT formed a 3D conductive network in the matrix without significant aggregation, which boosted the electrical-to-thermal properties of the scaffold, and the scaffold containing t-ZnO@MWCNT assembly possessed better electro-actuated shape memory properties with shape fixity of 98.0% and shape recovery of 98.8%., Conclusion: The scaffold exhibited improved electro-actuated shape memory properties and mechanical properties and the osteogenic inductivity was promoted with the combined effect of t-ZnO and electrical stimulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Production and hosting by Elsevier B.V.)

Epidermal stem cells (EpSCs) are crucial for wound healing and tissue regeneration, and traditional culture methods often lead to their inactivation. It is urgent to increase the yield of high quality EpSCs. In this study, primary EpSCs were isolated and cultured in a serum-free, feeder-free culture system. EpSCs are then expanded in a dynamic 3D environment using a rotating cell culture system (RCCS) with biodegradable porous microcarriers (MC). Over a period of 14 days, the cells self-assembled into microtissues with superior cell proliferation compared to 3D static culture. Immunofluorescence and qPCR analyses consistently showed that the stemness of the 3D microtissues was preserved, especially the COL17A1 associated with anti-aging was highly expressed in RCCS induced microtissues. In vivo experiments demonstrated that the group treated with 3D microtissues loaded with EpSCs showed enhanced early wound healing, and the injectable 3D microtissues were more conducive to maintaining cell viability and differentiation potential. Our study provides valuable insights into the dynamic 3D culture of EpSCs and introduces an injectable therapy using 3D microtissues loaded with EpSCs, which provides a new and effective approach for cell delivery and offering a promising strategy for guiding the regeneration of full-thickness skin defects., Competing Interests: The authors declare that they have no competing interests., (© 2024 Zhang et al.)

The reconstruction of craniomaxillofacial bone defects remains clinically challenging. To date, autogenous grafts are considered the gold standard but present critical drawbacks. These shortcomings have driven recent research on craniomaxillofacial bone reconstruction to focus on synthetic grafts with distinct materials and fabrication techniques. Among the various fabrication methods, additive manufacturing (AM) has shown significant clinical potential. AM technologies build three-dimensional (3D) objects with personalized geometry customizable from a computer-aided design. These layer-by-layer 3D biomaterial structures can support bone formation by guiding cell migration/proliferation, osteogenesis, and angiogenesis. Additionally, these structures can be engineered to degrade concomitantly with the new bone tissue formation, making them ideal as synthetic grafts. This review delves into the key advances of bioceramic grafts/scaffolds obtained by 3D printing for personalized craniomaxillofacial bone reconstruction. In this regard, clinically relevant topics such as ceramic-based biomaterials, graft/scaffold characteristics (macro/micro-features), material extrusion-based 3D printing, and the step-by-step workflow to engineer personalized bioceramic grafts are discussed. Importantly, in vitro models are highlighted in conjunction with a thorough examination of the signaling pathways reported when investigating these bioceramics and their effect on cellular response/behavior. Lastly, we summarize the clinical potential and translation opportunities of personalized bioceramics for craniomaxillofacial bone regeneration., (© 2024. The Author(s).)