In vivo engineered extracellular matrix scaffolds with instructive niches for oriented tissue regeneration

Passivated hydrogel interface: Armor against foreign body response and inflammation in small-diameter vascular grafts

The development of small-diameter vascular grafts (SDVGs) still faces significant challenges, particularly in overcoming blockages within vessels. A key issue is the foreign-body response (FBR) triggered by the implants, which impairs the integration between grafts and native vessels. In this study, we applied an interfacial infiltration strategy to create a stable, hydrophilic, and passivated hydrogel coating on SDVGs. This coating effectively resisted FBR and improved integration between the grafts and host tissue. We also incorporated anthocyanins, an antioxidant, into the hydrogel network to mitigate oxidative stress and promote endothelialization. The hydrogel coating exhibited excellent stability, retaining its integrity during continuous flushing over 15 days. Anthocyanins were released in response to reactive oxygen species (ROS), reducing inflammation and enhancing vascularization in a mouse subcutaneous implantation model. In a rabbit carotid artery replacement model, the SDVGs exhibited rapid endothelialization, guided vascular remodeling, and inhibited calcification, showing strong potential for clinical application. This study presents a straightforward and effective approach to improve the patency rate, endothelialization, and anti-calcification properties of SDVGs by equipping them with a protective anti-FBR and anti-inflammation hydrogel layer.

Biomimetic Microchannel Integrated Silk Fibroin Scaffold for Regeneration of Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is the primary cause of low back pain, and patients with severe degeneration usually require lumbar fusion or total disc arthroplasty. Lumbar fusion carries the risk of accelerated degeneration of the adjacent intervertebral disc (IVD), and total disc arthroplasty could reduce the risk. However, the clinical application of artificial IVD whose nondegradable properties make it difficult to restore the biological function of the IVD. Therefore, we intend to fabricate a novel biomimetic microchannel integrated silk fibroin scaffold (BMI-SF scaffold) containing annulus fibrosus with oriented cross-microchannels and nucleus pulposus with interconnected porous structure. The BMI-SF scaffold exhibits controllable microchannels as well as excellent biocompatibility and biodegradability. In vitro and in vivo studies have demonstrated that microchannels can direct cells into the BMI-SF scaffold and enhance neovascularization, supplying adequate nutritional support for tissue regeneration. The IVD replacement model showed that the BMI-SF scaffold has superior regenerative effects, such as restoring IVD height and providing motion segments with dynamic mechanical properties akin to the natural IVD. In this study, the BMI-SF scaffold developed using controlled microchannels provides a new strategy for patients with severe IVDD and has broad clinical application prospects.

Muscle-specific acellular ECM fibers made with anchored cell sheet engineering support regeneration in rat models of volumetric muscle loss

Volumetric muscle loss (VML), a condition affecting millions due to trauma, represents a critical unmet need in regenerative medicine, with no established standard of care. This study introduces a de novo therapeutic strategy using tissue-specific skeletal muscle acellular extracellular matrix (aECM) fibers fabricated using scaffold-free Anchored Cell Sheet Engineering technique. These engineered fibers replicate the native ECM composition and microarchitecture of skeletal muscle, incorporating essential structural and basement membrane proteins. In a rat VML model, aECM demonstrated promising regenerative capacity compared to commercial porcine-derived small intestine submucosa (SIS) ECM. Over an 8-week period, compared to contralateral muscle, aECM preserved muscle volume and weight, regulated inflammatory and fibrotic responses, and promoted vascularization. In contrast, SIS was rapidly degraded by week 4 and associated with fibrosis. Force recovery in aECM was lower at the 8-week time point (77 % compared to 91 % in control), but histological and immunohistochemical analyses revealed newly formed, dispersed muscle fibers exclusively in aECM treatment. Importantly, muscle weight was preserved only when aECM was used, resulting in similar normalized force-to-weight across all groups (87 % in aECM vs. 88 % in SIS). The histological analyses further demonstrated ongoing tissue remodeling, indicative of sustained regeneration, in contrast to the premature fibrotic healing observed in the other groups. An innovative quantitative image analysis workflow enabled assessment of spatial tissue heterogeneity through histology and immunohistochemistry images, setting a new standard for regeneration analysis. These findings establish engineered tissue-specific aECM as a transformative approach for VML treatment, laying the groundwork for translation to clinical applications. STATEMENT OF SIGNIFICANCE: The current study introduces a transformative approach to treating volumetric muscle loss (VML) through the development of tissue-specific acellular extracellular matrix (aECM) fibers engineered using a scaffold-free biofabrication platform uniquely suited for recreation of such aECM components. The engineered fibers represent a significant advancement over current commercial options by recreating native ECM composition and microarchitecture while eliminating complications associated with xenogenic materials. Through comprehensive in vivo evaluation in a rat model, it is demonstrated that these engineered fibers maintain muscle mass and promote controlled tissue regeneration, addressing key limitations of existing treatments. The scaffold-free biofabrication of tissue-specific aECM provides a new paradigm for biomaterial design in regenerative medicine.

One-Pot Synthesis of Antibacterial and Antioxidant Self-Healing Bioadhesives Using Ugi Four-Component Reactions

Bioadhesive materials are extensively utilized as alternatives to surgical sutures and wound dressings. Despite significant advancements in their synthesis, current bioadhesives suffer from inadequate mechanical stability, suboptimal wet tissue adhesion, and a lack of inherent antibacterial and antioxidant properties, while requiring multistep synthesis processes, complicating their production for biomedical applications. To address these limitations, we developed a new bioadhesive, named UgiGel, synthesized through a one-pot Ugi four-component reaction (Ugi-4CR). Our strategy utilized gelatin as the backbone, 4-formylphenylboronic acid (4-FPBA) as an aldehyde source for improved adhesion and antibacterial activity, gallic acid (GA) as a carboxylic acid source for improved antioxidant activity and wound healing, and cyclohexyl isocyanide (CyIso) to induce pseudopeptide structures. The internal crosslinking between GA and 4-FPBA via dynamic boronate ester bond formation, triggered by slight pH changes (7.4-7.8) and temperature elevation (25°C-40°C), resulted in the formation of viscoelastic and self-healing hydrogels with water as the only byproduct without the need for initiator/light activation. UgiGel showed higher adhesion to porcine skin tissue (139.8 ± 8.7 kPa) as compared to commercially available bioadhesives, Evicel (26.3 ± 2.6 kPa) and Coseal (19.3 ± 9.9 kPa). It also demonstrated effective antibacterial properties against both Gram-negative and Gram-positive bacteria, as well as antioxidant activity. Additionally, the in vitro studies using NIH-3T3 cells confirmed the biocompatibility of the UgiGel over 7 days of culture. Moreover, in vivo biocompatibility and biodegradation of UgiGel were confirmed via subcutaneous implantation in rats for up to 28 days. Our results demonstrated that UgiGel outperformed commercially available bioadhesives in terms of adhesion, self-healing, and antibacterial activity, without compromising biocompatibility or physical properties, representing a promising multifunctional bioadhesive for wound sealing and repair.

Bioactive Scaffolds with Ordered Micro/Nano-Scale Topological Surface for Vascularized Bone Regeneration

The ordered topological micro/nanostructures of scaffolds play a pivotal role in regulating bone development, remodeling, and regeneration. Nevertheless, achieving the integration of ordered micro/nanostructures into 3D scaffolds remains a formidable challenge. In this context, a brushing-assembly strategy is developed to construct 3D bioactive scaffolds with highly ordered micro/nanostructures. Such an engineered scaffold exhibits a positive regulatory effect on the behavior and fate of bone resident cells, such as mesenchymal stem cells (MSCs) and human umbilical vein endothelial cells (HUVECs), through mechanical stimulation provided by the ordered micro/nanostructures, while also allowing for the precise spatial distribution of multiple cell types through assembly. In vivo experiments demonstrate that scaffolds with ordered nanostructures possess the potential to accelerate vascularized bone regeneration. Overall, this work proposed a universal strategy for the fabrication of bioactive scaffolds with ordered topological micro/nanostructures, bridging the gap between 3D scaffolds and ordered surface microstructures for tissue engineering.

Implantation of MSC spheroid-derived 3D decellularized ECM enriched with the MSC secretome ameliorates traumatic brain injury and promotes brain repair

Traumatic brain injury (TBI) presents substantial clinical challenges, as existing treatments are unable to reverse damage or effectively promote brain tissue regeneration. Although implantable biomaterials have been proposed to support tissue repair by mitigating the adverse microenvironment in injured brains, many fail to replicate the complex composition and architecture of the native extracellular matrix (ECM), resulting in only limited therapeutic outcomes. This study introduces an innovative approach by developing a mesenchymal stem cell (MSC) spheroid-derived three-dimensional (3D) decellularized ECM (dECM) that is enriched with the MSC-derived matrisome and secretome, offering a promising solution for TBI treatment and brain tissue regeneration. Proteomic and cytokine array analyses revealed that 3D dECM retained a diverse array of MSC spheroid-derived matrisome proteins and secretome components, which are crucial for replicating the complexity of native ECM and the therapeutic capabilities of MSCs. These molecules were found to underlie the observed effects of 3D dECM on immunomodulation, proneuritogenesis, and proangiogenesis in our in vitro functional assays. Implantation of 3D dECM into TBI model mice effectively mitigated postinjury tissue damage and promoted brain repair, as evidenced by a reduced brain lesion volume, decreased cell apoptosis, alleviated neuroinflammation, reduced glial scar formation, and increased of neuroblast recruitment to the lesion site. These outcomes culminated in improved motor function recovery in animals, highlighting the multifaceted therapeutic potential of 3D dECM for TBI. In summary, our study elucidates the transformative potential of MSC spheroid-derived bioactive 3D dECM as an implantable biomaterial for effectively mitigating post-TBI neurological damage, paving the way for its broader therapeutic application.

Magnetic field-oriented conductive decellularized extracellular matrix hydrogel synergizes with electrical stimulation to promote spinal cord injury repair and electrophysiological function restoration

Spinal cord injury (SCI) results in electrophysiological and behavioral dysfunction. Electrical stimulation (ES) is considered to be an effective treatment for mild SCI; however, ES is not applicable to severe SCI due to the disruption of electrical conduction caused by tissue defects. Therefore, the use of conductive materials to fill the defects and restore electrical conduction in the spinal cord is a promising therapeutic strategy. In this study, we used ultrasound to composite conductive reduced graphene oxide (rGO) and magnetic Fe3O4 nanoparticles and encapsulated them into gelatin methacryloyl (GelMA) along with decellularized extracellular matrix (dECM) to form a conductive composite hydrogel, rGO/Fe3O4/dECM@GelMA. The rGO/Fe3O4 complexes were able to orientate themselves in the hydrogel with a magnetic field, conferring an orientated electrical conduction function to the hydrogel. The implantation of this composite hydrogel re-established the electrical conduction in the damaged spinal cord and synergized with ES to promote the regeneration of neurons and myelinated axons at the injury site, resulting in the restoration of electrophysiological function of the spinal cord and motor function of the hind limbs of mice. Our study combines a conductive tissue-engineered scaffold with ES therapy to improve the efficacy of ES in severe spinal cord injuries and promote the restoration of spinal cord function.

Constructing a 3D co-culture in vitro synovial tissue model for rheumatoid arthritis research

The development and exploration of highly effective drugs for rheumatoid arthritis remains an urgent necessity. However, current disease research models are no longer sufficient to meet the rapid development of high-throughput drug screening. In this study, bacterial cellulose simulating the structure of extracellular matrix was used as a 3D culture platform, and THP-1-derived M1 macrophages, representing the inflammatory component, human umbilical vein endothelial cells (HUVECs), simulating the vascular component, and rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs), embodying the synovial pathology, were co-cultured to simulate the pathological microenvironment in RA synovial tissues, and synovial organoids were constructed. Under three-dimensional (3D) culture conditions, there was a notable upregulation of fatty acid-binding protein 4 (FABP4) in polarized macrophages, and an enhancement of pathological phenotypes in HUVECs and RA-FLSs, mediated through the PI3K/AKT signaling pathway, including cell proliferation, migration, invasion and vascularization. Compared to planar cultures and 2D co-cultures, 3D synovial organoids not only exhibit a broader range of transcriptomic features characteristic of rheumatoid arthritis but also demonstrate increased drug resistance, likely due to the more complex and physiologically relevant cell-cell and cell-matrix interactions present in 3D environments. This model offers a promising path for personalized treatment, accelerating precision medicine in rheumatology.

Inflammation-modulating elastic decellularized extracellular matrix scaffold promotes meniscus regeneration

Scaffold-guided meniscus repair and regeneration show promise for meniscus injuries. Desirable scaffold properties are key to promoting proper tissue remodeling and effective regeneration. Herein, we report an inflammation-modulating elastic decellularized extracellular matrix (ECM) scaffold and evaluate its biological performance on meniscus repair in a rabbit model. An elastic scaffold of decellularized meniscus ECM (dmECM) was first prepared and functionalized with chitosan (CS) and ibuprofen (IBU) to obtain dmECM/CS-IBU scaffold. Our results show that CS and IBU grafting did not affect the overall properties of the dmECM/CS-IBU scaffold, including porous structure, good mechanical strength and elasticity. It promoted chondrocyte proliferation and preserved chondrogenic properties. In addition, both in vitro and in vivo assessments indicate that the dmECM/CS-IBU scaffold showed good anti-inflammatory properties and promoted pro-healing polarization of macrophages. In a partial rabbit meniscus defect model, the dmECM/CS-IBU scaffold showed promotive effects on in situ meniscus repair and preserved cartilage tissue. Therefore, our study provides a feasible strategy for fabricating scaffolds with tissue-specific bioactivity and inflammation-modulating abilities that synergistically promote meniscus repair and regeneration. STATEMENT OF SIGNIFICANCE: Desirable scaffold properties are key to promoting proper tissue remodeling and effective regeneration of meniscus injuries. Herein, elastic decellularized scaffolds were prepared using natural meniscus and successfully grafted with chitosan and the anti-inflammatory drug ibuprofen (dmECM/CS-IBU). The dmECM/CS-IBU scaffold showed a pro-proliferative and phenotype- preserving effect on chondrocytes. In both in vitro and in vivo models, dmECM/CS-IBU scaffolds exhibited wonderful anti-inflammatory activity. In a meniscus white zone defect model, the dmECM/CS-IBU scaffold demonstrated in situ repair of tissue and protection of cartilage tissue. Therefore, we provides a feasible strategy for fabricating scaffolds with tissue-specific bioactivity and inflammation-modulating abilities that synergistically promote meniscus repair and regeneration.

Machine Learning-Driven Identification of Exosome-Related Genes in Head and Neck Squamous Cell Carcinoma for Prognostic Evaluation and Drug Response Prediction

Background: This study integrated four Gene Expression Omnibus (GEO) datasets to identify disease-specific feature genes in head and neck squamous cell carcinoma (HNSCC) through differential expression analysis with batch effect correction. Methods: The GeneCards database was used to find genes related to exosomes, and samples were categorized into groups with high and low expression levels based on these feature genes. Functional and pathway enrichment analyses (GO, KEGG, and GSEA) were used to investigate the possible biological mechanisms underlying feature genes. A predictive model was produced by using machine learning algorithms (LASSO regression, SVM, and random forest) to find disease-specific feature genes. Receiver operating characteristic (ROC) curve analysis was used to assess the model's effectiveness. The diagnostic model showed excellent predictive accuracy through external data GSE83519 validation. Results: This analysis highlighted 22 genes with significant differential expression. A predictive model based on five important genes (AGRN, TSPAN6, MMP9, HBA1, and PFN2) was produced by using machine learning algorithms. MMP9 and TSPAN6 showed relatively high predictive performance. Using the ssGSEA algorithm, three key genes (MMP9, AGRN, and PFN2) were identified as strongly linked to immune regulation, immune response suppression, and critical signaling pathways involved in HNSCC progression. Matching HNSCC feature gene expression profiles with DSigDB compound signatures uncovered potential therapeutic targets. Molecular docking simulations identified ligands with high binding affinity and stability, notably C5 and Hoechst 33258, which were prioritized for further validation and potential drug development. Conclusions: This study employs a novel diagnostic model for HNSCC constructed using machine learning technology, which can provide support for the early diagnosis of HNSCC and thus contribute to improving patient treatment plans and clinical management strategies.

Regulating Cell-Material Interfacial Interactions through Selective Cellular Resistance

Regulating the behavior of different types of cells at the material-tissue interface is pivotal for inducing tissue regeneration. Traditional methods enhance target cell activity using specific ligands such as peptides and antibodies, which have stability issues within biological environments. Herein, we show that selective cell resistance can be realized by fine-tuning the material surface chemistry, achieving strong cell selectivity superior to that of extracellular matrix peptides. A certain degree of adsorption resistance differentially affects the adhesion of various types of cells on material surfaces. Taking this principle into account, a polyethylene glycol (PEG) grafted surface was meticulously fine-tuned to selectively support endothelial cells (ECs) while resisting smooth muscle cell attachment. Mechanistic studies identified that the difference in myosin II expression is crucial for cell selectivity. An EC-selective polymer coating for cardiovascular devices was fabricated to promote rapid surface endothelialization and prevent neointimal hyperplasia in vivo.

Three-dimensional tissue platform co-laid with native collagen fibers and cells for phenotypic screening of stem cell interactions

Phenotypic screening of cell-cell and cell-matrix interactions is critical yet challenging for drug discovery and disease modeling. In this study, a scalable 3D tissue platform was developed by co-laying extracted natural insoluble collagen fibers, mesenchymal stem cells, endothelial cells, and neural progenitor cells for phenotypic screening. Cell growth and interactions were enhanced in the co-laid platform, evident through increased cell proliferation, viability, and vascularization. Dense vascular networks rapidly formed through cell-cell and cell-matrix interactions without adding a traditionally needed growth factor set. Both in vitro and implantation studies confirmed that these blood vessels were of human origin. To evaluate the phenotypic screening of cell-cell and cell-matrix interactions, we propose a phenotype screening prototype for stem cell interactions that utilized multivariate analysis encompassing both cell-cell and cell-matrix interactions and demonstrated its effectiveness to screen vasculature formation and autism spectrum disorder (ASD) models. Using the prototype, we confirmed that collagen crosslinking, ROCK, WNT, and YAP pathways impact vasculogenesis. In addition, ASD donor-derived neural progenitor cells can be distinguished from non-ASD control donor-derived neural progenitor cells.

Directional Mushroom-Derived Scaffold for Microenvironment Regulation in Infected Bone Defects

Infected bone defects are a common clinical condition, but conventional treatments often fail to achieve the desired outcomes, including addressing antibiotic resistance and preventing nonunion complications. In the presented study, a functionalized decellularized mushroom stem scaffold is developed composed of its naturally aligned channels, Zn2+/curcumin MOFs, hydroxyapatite minerals, and icariin. In vitro, It is found that functionalized acellular mushroom stem scaffold can control bacterial infections through Zn2+/curcumin MOFs. The naturally aligned channels guide bone mesenchymal stem cells (BMSCs) migration, and the components adsorbed on the acellular substrate further promote the migration of BMSCs. Moreover, these functional components further accelerated the polarization of M2 macrophage and osteogenic differentiation of BMSCs. In vivo, the functionalized decellularized mushroom stem scaffold cleared infected bacteria within 3 days, induced extracellular matrix secretion and alignment, and promoted new bone formation to cover defects within 8 weeks. The functionalized decellularized mushroom stem scaffold provides a promising strategy for treating infectious bone defects.

Masquelet Inspired in Vivo Engineered Extracellular Matrix as Functional Periosteum for Bone Defect Repair and Reconstruction

The Masquelet technique that combines a foreign body reaction (FBR)-induced vascularized tissue membrane with staged bone grafting for reconstruction of segmental bone defect has gained wide attention in Orthopedic surgery. The success of Masquelet hinges on its ability to promote formation of a "periosteum-like" FBR-induced membrane at the bone defect site. Inspired by Masquelet's technique, here a novel approach is devised to create periosteum mimetics from decellularized extracellular matrix (dECM), engineered in vivo through FBR, for reconstruction of segmental bone defects. The approach involved 3D printing of polylactic acid (PLA) template with desired pattern/architecture, followed by subcutaneous implantation of the template to form tissue, and depolymerization and decellularization to generate dECM with interconnected channels. The dECM matrices produces from the same mice (autologous) or from different mice (allogenic) are used as a functional periosteum for repair of structural bone allograft in a murine segmental bone defect model. This study shows that autologous dECM performed better than allogenic dECM, further permitting local delivery of low dose BMP-2 to enhance allograft incorporation. The success of this current approach can establish a new line of versatile, patient-specific, and periosteum-like autologous dECM for bone regeneration, offering personalized therapeutics to patients with impaired healing.

Fabrication and in vitro cytocompatibility evaluation of porous bone scaffold based on cuttlefish bone-derived nano-carbonated hydroxyapatite reinforced with polyethylene oxide/chitosan fibrous structure

A novel porous bone scaffold based on nano-carbonated hydroxyapatite reinforced with fibrous-like structured polyethylene oxide/chitosan network (nCHA/PEO/CS) was introduced and fabricated via freeze-drying. Prior to this, the nCHA was synthesized through a hydrothermal reaction based on cuttlefish bone (CFB, Sepia officinalis). The raw cuttlefish bone (raw-CFB) was first decomposed to obtain cuttlefish bone-derived calcium oxide (CaO-CFB) by calcination at 1000 °C, which was used for synthesizing nCHA. The chemical composition analysis showed that the nCHA formed AB-type CHA with a high carbonate content of 7.38 wt%, which is in the range of carbonate content in native bone (2-9 wt%). The Ca/P molar ratio of nCHA was 1.712, very close to the Ca/P of biological apatite of 1.71. Morphological analysis revealed that nCHA consists of nanosized particles, potentially offering a large surface area to volume to promote ion exchange and cell interaction. The excellent physicochemical and morphological properties of nCHA proposed suitability as a bone scaffold precursor combined with PEO and CS. The nCHA/PEO/CS scaffolds were freeze-dried with varying PEO/CS concentrations. Physicochemical analysis indicated that increasing the PEO/CS concentration decreased the crystallinity of the scaffold, causing it to be lower than the nCHA crystallinity, which may be beneficial for cell growth. Morphological analysis revealed that the scaffold structure comprised nCHA cross-linked within a fibrous-like structured PEO/CS network, which appropriately mimics the fibrous structure of extracellular matrix (ECM) in natural bone. However, the nCHA/PEO/CS-11 scaffold formed more appropriate pores with suitable porosity for cell development, blood vessel formation, and nutrient perfusion. The nCHA/PEO/CS-11 scaffold also demonstrated sufficient compressive strength and good swelling behavior, which may favor bone regeneration. The nCHA/PEO/CS-11 scaffold demonstrated high cytocompatibility and facilitated the adherence of MC3T3E1 cells on the scaffold surface. The nCHA/PEO/CS-11 scaffold also promoted cell osteogenic differentiation. Owing to its desirable and suitable characteristics, the nCHA/PEO/CS-11 scaffold is promising in bone tissue engineering.

Modeling of a Bioengineered Immunomodulating Microenvironment for Cell Therapy

Cell delivery and encapsulation platforms are under development for the treatment of Type 1 Diabetes among other diseases. For effective cell engraftment, these platforms require establishing an immune-protected microenvironment as well as adequate vascularization and oxygen supply to meet the metabolic demands of the therapeutic cells. Current platforms rely on 1) immune isolating barriers and indirect vascularization or 2) direct vascularization with local or systemic delivery of immune modulatory molecules. Supported by experimental data, here a broadly applicable predictive computational model capable of recapitulating both encapsulation strategies is developed. The model is employed to comparatively study the oxygen concentration at different levels of vascularization, transplanted cell density, and spatial distribution, as well as with codelivered adjuvant cells. The model is then validated to be predictive of experimental results of oxygen pressure and local and systemic drug biodistribution in a direct vascularization device with local immunosuppressant delivery. The model highlights that dense vascularization can minimize cell hypoxia while allowing for high cell loading density. In contrast, lower levels of vascularization allow for better drug localization reducing systemic dissemination. Overall, it is shown that this model can serve as a valuable tool for the development and optimization of platform technologies for cell encapsulation.

Injectable tissue-engineered human cartilage matrix composite fibrin glue for regeneration of articular cartilage defects

Due to the lack of blood vessels and nerves, the ability of cartilage to repair itself is limited, and the injury of articular cartilage urgently needs effective treatment. Currently, the limitation of clinical repair for cartilage defects is that it is difficult to form pure hyaline cartilage repair, and the source of cartilage tissue and cells is limited. To obtain high-purity regenerated hyaline cartilage, we proposed to construct an injectable hydrogel precursor by using human living hyaline cartilage graft (hLhCG) secreted by human chondrocytes as the dispersed phase and fibrinogen solution as the continuous phase, by double injection with thrombin, three-dimensional network hydrogel structure was formed under the action of thrombin to repair joint defects. The component phenotypes of hLhCG and biomechanical properties of composite gel scaffolds were verified. After 12 weeks of injection of the mixed phase at the defect site, the regenerated tissues are similar in composition to adjacent natural tissues and exhibit similar biomechanical properties. The phenotype of regenerated cartilage was verified, confirming the successful regeneration of hyaline cartilage.

Evaluation methods for decellularized tissues: A focus on human amniotic membrane

Tissue engineering, a multidisciplinary research field aiming to revolutionize regenerative medicine, relies on scaffolds for optimal cell cultures and organ development. Decellularized tissue extracellular matrices (dECM) scaffolds, particularly from human amniotic membrane (hAM), show promise in clinical applications. This review discusses the significance of scaffolds, emphasizing dECM-based hAM scaffolds, delving into ECM complexities, decellularization processes, and evaluation methods. Raman spectroscopy emerges as a non-destructive tool for evaluating ECM preservation, presenting potential for quantifying ECM components in hAM before and after decellularization. The review explores the role of hAM as a biomaterial, detailing its composition and characteristics and emphasizes the importance of evaluating ultrastructural components and suggests Raman spectroscopy as a valuable technique for this purpose.

Cell Homing Strategies in Regenerative Endodontic Therapy

Cell homing, a process that leverages the body's natural ability to recruit cells and repair damaged tissues, presents a promising alternative to cell transplantation methods. Central to this approach is the recruitment of endogenous stem/progenitor cells-such as those from the apical papilla, bone marrow, and periapical tissues-facilitated by chemotactic biological cues. Moreover, biomaterial scaffolds embedded with signaling molecules create supportive environments, promoting cell migration, adhesion, and differentiation for the regeneration of the pulp-dentin complex. By analyzing in vivo animal studies using cell homing strategies, this review explores how biomolecules and scaffold materials enhance the recruitment of endogenous stem cells to the site of damaged dental pulp tissue, thereby promoting repair and regeneration. It also examines the key principles, recent advancements, and current limitations linked to cell homing-based regenerative endodontic therapy, highlighting the interplay of biomaterials, signaling molecules, and their broader clinical implications.

Progress in Biomaterials-Enhanced Vascularization by Modulating Physical Properties

Sufficient vascular system and adequate blood perfusion is crucial for ensuring nutrient and oxygen supply within biomaterials. Actively exploring the optimal physical properties of biomaterials in various application scenarios has provided clues for enhancing vascularization within materials, leading to improved outcomes in tissue engineering and clinical translation. Here we focus on reviewing the physical properties of biomaterials, including pore structure, surface topography, and stiffness, and their effects on promoting vascularization. This angiogenic capability has the potential to provide better standardized research models and personalized treatment strategies for bone regeneration, wound healing, islet transplantation and cardiac repair.

Biofabrication of anisotropic articular cartilage based on decellularized extracellular matrix

Tissue-engineered grafts that mimic articular cartilage show promise for treating cartilage injuries. However, engineering cartilage cell-based therapies to match zonal architecture and biochemical composition remains challenging. Decellularized articular cartilage extracellular matrix (dECM) has gained attention for its chondro-inductive properties, yet dECM-based bioinks have limitations in mechanical stability and printability. This study proposes a rapid light-based bioprinting method using a tyrosine-based crosslinking mechanism, which does not require chemical modifications of dECM and thereby preserves its structure and bioactivity. Combining this resin with Filamented Light (FLight) biofabrication enables the creation of cellular, porous, and anisotropic dECM scaffolds composed of aligned microfilaments. Specifically, we focus on the effects of various biopolymer compositions (i.e. hyaluronic acid, collagen I, and dECM) and inner architecture (i.e. bulk light vs FLight) on immune response and cell morphology, and we investigate their influence on nascent ECM production and long-term tissue maturation. Our findings highlight the importance of FLight scaffolds in directing collagen deposition resembling articular cartilage structure and promoting construct maturation, and they emphasize the superiority of biological-rich dECM over single-component materials for engineering articular cartilage, thereby offering new avenues for the development of effective cartilage tissue engineering strategies.

Biomimetic Versatile Anisotropic, Electroactive Cellulose Hydrogel Scaffolds Tailored from Fern Stem Serving as Nerve Conduit and Cardiac Patch

Peripheral nerve injury (PNI) and myocardial infarction (MI) are the two most clinically common soft excitable tissue injuries. Both nerve and cardiac tissues exhibit structural anisotropy and electrophysiological activity, providing a wide range of biophysical cues for cell and tissue repair. However, balancing microstructural anisotropy, electroactivity, and biocompatibility is challenging. To address this issue, Dicranopteris linearis (D. linearis) is proposed as a low-perceived value fern plant. Moreover, to enhance its usefulness, it can be designed into a tubular structure and a lamellar structure to bridge the damaged tissue. Therefore, a robust yet simple top-down approach is proposed to designing and fabricating the desired biomimetic versatile hydrogels orienting from the D. linearis to customize for different soft excitable tissue repair applications. These anisotropic electroactive hydrogels performed well as nerve guidance conduits (NGC) and engineered cardiac patches (ECP) in the repair of PNI and MI, respectively. Two birds, one stone. Accordingly, the biomimetic strategy of D. linearis to NGC and D. linearis to ECP is first proposed, opening a new horizon for constructing tissue engineering using natural sources.

Advances in tissue engineering of peripheral nerve and tissue innervation - a systematic review

Although various options are available to treat injured organs and peripheral nerves, none is without limitations. Auto- and allografts are the first choice of treatment, but tissue survival or functionality is not guaranteed due to often limited vascular and neural networks. In response, tissue-engineered solutions have been developed, yet clinical translations is rare. In this study, a systematic review was performed on tissue-engineered advancements for peripheral nerves and tissues, to aid future developments in bridging the gap toward the clinic by identifying high-potential solutions and unexplored areas. A systematic search was performed in PubMed, Embase, Web of Science, and Scopus until November 9, 2023. Search terms involved "tissue engineering," "guided," "tissue scaffold," and "tissue graft," together with "innervation" and "reinnervation." Original in vivo or in vitro studies meeting the inclusion criteria (tissue-engineered peripheral nerve/innervation of tissue) and no exclusion criteria (no full text available; written in foreign language; nonoriginal article; tissue-engineering of central nervous system; publication before 2012; insufficient study quality or reproducibility) were assessed. A total of 68 out of 3626 original studies were included. Data extraction was based on disease model, cell origin and host species, biomaterial nature and composition, and external stimuli of biological, chemical or physical origin. Although tissue engineering is still in its infancy, explored innervation strategies of today were highlighted with respect to biomaterials, cell types, and external stimuli. The findings emphasize that natural biomaterials, pre-seeding with autologous cell sources, and solutions for reproductive organs are beneficial for future research. Natural biomaterials possess important cues required for cell-material interaction and closely resemble native tissue in terms of biomechanical, geometrical and chemical composition. Autologous cells induce biomaterial functionalization. As these solutions pose no risk of immunorejection and have demonstrated good outcomes, they are most likely to fulfill the clinical demands.

Physical stimuli-responsive polymeric patches for healthcare

Many chronic diseases have become severe public health problems with the development of society. A safe and efficient healthcare method is to utilize physical stimulus-responsive polymer patches, which may respond to physical stimuli, including light, electric current, temperature, magnetic field, mechanical force, and ultrasound. Under certain physical stimuli, these patches have been widely used in therapy for diabetes, cancer, wounds, hair loss, obesity, and heart diseases since they could realize controllable treatment and reduce the risks of side effects. This review sketches the design principles of polymer patches, including composition, properties, and performances. Besides, control methods of using different kinds of physical stimuli were introduced. Then, the fabrication methods and characterization of patches were explored. Furthermore, recent applications of these patches in the biomedical field were demonstrated. Finally, we discussed the challenges and prospects for its clinical translation. We anticipate that physical stimulus-responsive polymer patches will open up new avenues for healthcare by acting as a platform with multiple functions.

A sterilization method for human decellularized vaginal matrices

Vaginal reconstruction is necessary for various congenital and acquired conditions, including vaginal aplasia, trauma, tumors, and gender incongruency. Current surgical and non-surgical treatments often result in significant complications. Decellularized vaginal matrices (DVMs) from human tissue offer a promising alternative, but require effective sterilization to ensure safety and functionality. This study aimed to develop a sterilization method for decellularized human vaginal wall scaffolds. Based on our previously implemented decellularization technique with minor modifications, we designed and examined three sterilization methods consisting of (i) chemical decellularization, (ii) decellularization with additional peracetic acid/hydrogen peroxide (PAA/H2O2); (iii) decellularization with antibiotic and antimycotic (AAE) based treatment. Sterilization efficacy was evaluated through controlled contamination with common vaginal microbes and sterility testing subsequent to each sterilization method. The extracellular matrix (ECM) structure was assessed via histological staining. Decellularization alone reduced some added bacterial contaminants but did not achieve complete sterilization. PAA/H2O2-sterilization resulted in severe ECM damage, rendering it unsuitable. The AAE-treatment demonstrated effective sterilization without compromising the ECM structure. Combined decellularization and AAE-based treatment forms a viable sterilization method for human vaginal wall tissue, maintaining ECM integrity and achieving effective micro-organism elimination. This method holds potential for clinical application in vaginal transplantation.

Integrating Physical and Biochemical Cues for Muscle Engineering: Scaffolds and Graft Durability

Muscle stem cells (MuSCs) are essential for skeletal muscle regeneration, influenced by a complex interplay of mechanical, biochemical, and molecular cues. Properties of the extracellular matrix (ECM) such as stiffness and alignment guide stem cell fate through mechanosensitive pathways, where forces like shear stress translate into biochemical signals, affecting cell behavior. Aging introduces senescence which disrupts the MuSC niche, leading to reduced regenerative capacity via epigenetic alterations and metabolic shifts. Transplantation further challenges MuSC viability, often resulting in fibrosis driven by dysregulated fibro-adipogenic progenitors (FAPs). Addressing these issues, scaffold designs integrated with pharmacotherapy emulate ECM environments, providing cues that enhance graft functionality and endurance. These scaffolds facilitate the synergy between mechanotransduction and intracellular signaling, optimizing MuSC proliferation and differentiation. Innovations utilizing human pluripotent stem cell-derived myogenic progenitors and exosome-mediated delivery exploit bioactive properties for targeted repair. Additionally, 3D-printed and electrospun scaffolds with adjustable biomechanical traits tackle scalability in treating volumetric muscle loss. Advanced techniques like single-cell RNA sequencing and high-resolution imaging unravel muscle repair mechanisms, offering precise mapping of cellular interactions. Collectively, this interdisciplinary approach fortifies tissue graft durability and MuSC maintenance, propelling therapeutic strategies for muscle injuries and degenerative diseases.

Emerging technologies in regenerative medicine: The future of wound care and therapy

Wound healing, an intricate biological process, comprises orderly phases of simple biological processed including hemostasis, inflammation, angiogenesis, cell proliferation, and ECM remodeling. The regulation of the shift in these phases can be influenced by systemic or environmental conditions. Any untimely transitions between these phases can lead to chronic wounds and scarring, imposing a significant socio-economic burden on patients. Current treatment modalities are largely supportive in nature and primarily involve the prevention of infection and controlling inflammation. This often results in delayed healing and wound complications. Recent strides in regenerative medicine and tissue engineering offer innovative and patient-specific solutions. Mesenchymal stem cells (MSCs) and their secretome have gained specific prominence in this regard. Additionally, technologies like tissue nano-transfection enable in situ gene editing, a need-specific approach without the requirement of complex laboratory procedures. Innovating approaches like 3D bioprinting and ECM bioscaffolds also hold the potential to address wounds at the molecular and cellular levels. These regenerative approaches target common healing obstacles, such as hyper-inflammation thereby promoting self-recovery through crucial signaling pathway stimulation. The rationale of this review is to examine the benefits and limitations of both current and emerging technologies in wound care and to offer insights into potential advancements in the field. The shift towards such patient-centric therapies reflects a paradigmatic change in wound care strategies.

Biomimetic multi-channel nerve conduits with micro/nanostructures for rapid nerve repair

Peripheral nervous system (PNS) injuries often lead to significant sensory and motor impairments. Traditional artificial nerve conduits, lacking anisotropic structures, have been associated with prolonged repair time and failures in nerve regeneration. This study aimed to address these challenges by developing a novel approach for rapid repair of peripheral nerve injuries (PNI). A 3D oriented fibers scaffold featuring distinct radial (RFs) and longitudinal (LFs) fibers orientations was engineered using coaxial electrospinning and gas directional foaming techniques. This scaffold was then integrated with a shape memory conduit to form a directional multi-channel nerve conduit with micro/nanostructures. The results revealed that the grooved surface of the fibers significantly improved cellular directional guidance, effectively facilitating the migration of SCs from the periphery towards the center and from the base to the apex of the scaffold. In a rat model with a 10 mm nerve defect, the ND-PLATMC/LF ND-PCL scaffold significantly enhanced nerve regeneration and motor function recovery within 4 weeks. These results suggest the potential of this innovative scaffold for efficient repair of the nerve injuries.

iPSC-derived and Patient-Derived Organoids: Applications and challenges in scalability and reproducibility as pre-clinical models

Recent advancements in stem cell technology have led to the development of organoids - three-dimensional (3D) cell cultures that closely mimic the structural and functional characteristics of human organs. These organoids represent a significant improvement over traditional two-dimensional (2D) cell cultures by preserving native tissue architecture and cellular interactions critical for physiological relevance. This review provides a comprehensive comparison between two main types of organoids: induced Pluripotent Stem Cell (iPSC)-derived and Adult Stem Cell (ASC)-derived (also known as Patient-Derived Organoids, PDOs). iPSC-derived organoids, derived from reprogrammed cells, exhibit remarkable plasticity, and can model a wide range of tissues and developmental stages. They are particularly valuable for studying early human development, genetic disorders, and complex diseases. However, challenges such as prolonged differentiation protocols and variability in maturation levels remain significant hurdles. In contrast, ASC-derived organoids, generated directly from patient tissues, faithfully recapitulate tissue-specific characteristics and disease phenotypes. This fidelity makes them indispensable for personalized medicine applications, including drug screening, disease modeling, and understanding individualized treatment responses. The review highlights the unique advantages and limitations of each organoid type, emphasizing their roles in advancing biomedical research and drug discovery. It addresses key challenges in organoid technology, such as scalability, reproducibility, and the need for standardized culture protocols. Furthermore, it explores recent innovations in scaffold-guided organoid engineering and the integration of organoids with advanced technologies like artificial intelligence and high-throughput screening. The integration of organoids with cutting-edge technologies holds promise for enhancing their utility in modeling complex human diseases and accelerating drug discovery and development. By providing more physiologically relevant models of human organs, organoid technology is poised to revolutionize biomedical research, offering new insights into disease mechanisms and personalized therapeutic strategies.

Co-assembling bioactive short peptide nanofibers coated silk scaffolds induce neurite outgrowth of PC12 cells

Controlling biomolecular-cell interactions is crucial for the design of scaffolds for tissue engineering (TE). Regenerated silk fibroin (RSF) has been extensively used as TE scaffolds, however, RSF showed poor attachment of neuronal cells, such as rat pheochromocytoma (PC12) cells. In this work, amphiphilic peptides containing a hydrophobic isoleucine tail (I3) and laminin or fibronectin derived peptides (IKVAV, PDSGR, YIGSR, RGDS and PHSRN) were designed for promoting scaffold-cell interaction. Three of them (I3KVAV, I3RGDS and I3YIGSR) can self-assemble into nanofibers, therefore, were used to enhance the application of RSF in neuron TE. Live / dead assays revealed that the peptides exhibited negligible cytotoxicity against PC12 cells. The specific interaction between PC12 cells and the peptides were investigate using atomic force microscopy (AFM). The results indicated a synergistic effect in the designed peptides, promoting cellular attachment, proliferation and morphology changes. In addition, AFM results showed that co-assembling peptides I3KVAV and I3YIGSR possesses the best regulation of proliferation and attachment of PC12 cells, consistent with immunofluorescence staining results. Moreover, cell culture with hydrogels revealed that a mixture of peptides I3KVAV and I3YIGSR can also promote 3D neurites outgrowth. The approach of combining two different self-assembling peptides shows great potential for nerve regeneration applications.

Mechanical strategies to promote vascularization for tissue engineering and regenerative medicine

Vascularization is a major challenge in the field of tissue engineering and regenerative medicine. Mechanical factors have been demonstrated to play a fundamental role in vasculogenesis and angiogenesis and can affect the architecture of the generated vascular network. Through the regulation of mechanical factors in engineered tissues, various mechanical strategies can be used to optimize the preformed vascular network and promote its rapid integration with host vessels. Optimization of the mechanical properties of scaffolds, including controlling scaffold stiffness, increasing surface roughness and anisotropic structure, and designing interconnected, hierarchical pore structures, is beneficial for the in vitro formation of vascular networks and the ingrowth of host blood vessels. The incorporation of hollow channels into scaffolds promotes the formation of patterned vascular networks. Dynamic stretching and perfusion can facilitate the formation and maturation of preformed vascular networks in vitro. Several indirect mechanical strategies provide sustained mechanical stimulation to engineered tissues in vivo, which further promotes the vascularization of implants within the body. Additionally, stiffness gradients, anisotropic substrates and hollow channels in scaffolds, as well as external cyclic stretch, boundary constraints and dynamic flow culture, can effectively regulate the alignment of vascular networks, thereby promoting better integration of prevascularized engineered tissues with host blood vessels. This review summarizes the influence and contribution of both scaffold-based and external stimulus-based mechanical strategies for vascularization in tissue engineering and elucidates the underlying mechanisms involved.

Probing Nanotopography-Mediated Macrophage Polarization via Integrated Machine Learning and Combinatorial Biophysical Cue Mapping

Inflammatory responses, leading to fibrosis and potential host rejection, significantly hinder the long-term success and widespread adoption of biomedical implants. The ability to control and investigated macrophage inflammatory responses at the implant-macrophage interface would be critical for reducing chronic inflammation and improving tissue integration. Nonetheless, the systematic investigation of how surface topography affects macrophage polarization is typically complicated by the restricted complexity of accessible nanostructures, difficulties in achieving exact control, and biased preselection of experimental parameters. In response to these problems, we developed a large-scale, high-content combinatorial biophysical cue (CBC) array for enabling high-throughput screening (HTS) of the effects of nanotopography on macrophage polarization and subsequent inflammatory processes. Our CBC array, created utilizing the dynamic laser interference lithography (DLIL) technology, contains over 1 million nanotopographies, ranging from nanolines and nanogrids to intricate hierarchical structures with dimensions ranging from 100 nm to several microns. Using machine learning (ML) based on the Gaussian process regression algorithm, we successfully identified certain topographical signals that either repress (pro-M2) or stimulate (pro-M1) macrophage polarization. The upscaling of these nanotopographies for further examination has shown mechanisms such as cytoskeletal remodeling and ROCK-dependent epigenetic activation to be critical to the mechanotransduction pathways regulating macrophage fate. Thus, we have also developed a platform combining advanced DLIL nanofabrication techniques, HTS, ML-driven prediction of nanobio interactions, and mechanotransduction pathway evaluation. In short, our developed platform technology not only improves our ability to investigate and understand nanotopography-regulated macrophage inflammatory responses but also holds great potential for guiding the design of nanostructured coatings for therapeutic biomaterials and biomedical implants.

Decellularized, Heparinized Small-Caliber Tissue-Engineered "Biological Tubes" for Allograft Vascular Grafts

There remains a lack of small-caliber tissue-engineered blood vessels (TEBVs) with wide clinical use. Biotubes were developed by electrospinning and in-body tissue architecture (iBTA) technology to prepare small-caliber TEBVs with promising applications. Different ratios of hybrid fibers of poly(l-lactic-co-ε-caprolactone) (PLCL) and polyurethane (PU) were obtained by electrospinning, and the electrospun tubes were then implanted subcutaneously in the abdominal area of a rabbit (as an in vivo bioreactor). The biotubes were harvested after 4 weeks. They were then decellularized and cross-linked with heparin. PLCL/PU electrospun vascular tubes, decellularized biotubes (D-biotubes), and heparinized combined decellularized biotubes (H + D-biotubes) underwent carotid artery allograft transplantation in a rabbit model. Vascular ultrasound follow-up and histological observation revealed that the biotubes developed based on electrospinning and iBTA technology, after decellularization and heparinization cross-linking, showed a better patency rate, adequate mechanical properties, and remodeling ability in the rabbit model. IBTA technology caused a higher patency, and the heparinization cross-linking process gave the biotubes stronger mechanical properties.

Versatile Design of NO-Generating Proteolipid Nanovesicles for Alleviating Vascular Injury

Vascular injury is central to the pathogenesis and progression of cardiovascular diseases, however, fostering alternative strategies to alleviate vascular injury remains a persisting challenge. Given the central role of cell-derived nitric oxide (NO) in modulating the endogenous repair of vascular injury, NO-generating proteolipid nanovesicles (PLV-NO) are designed that recapitulate the cell-mimicking functions for vascular repair and replacement. Specifically, the proteolipid nanovesicles (PLV) are versatilely fabricated using membrane proteins derived from different types of cells, followed by the incorporation of NO-generating nanozymes capable of catalyzing endogenous donors to produce NO. Taking two vascular injury models, two types of PLV-NO are tailored to meet the individual requirements of targeted diseases using platelet membrane proteins and endothelial membrane proteins, respectively. The platelet-based PLV-NO (pPLV-NO) demonstrates its efficacy in targeted repair of a vascular endothelium injury model through systemic delivery. On the other hand, the endothelial cell (EC)-based PLV-NO (ePLV-NO) exhibits suppression of thrombosis when modified onto a locally transplanted small-diameter vascular graft (SDVG). The versatile design of PLV-NO may enable a promising therapeutic option for various vascular injury-evoked cardiovascular diseases.

Sputtering thin films: Materials, applications, challenges and future directions

Sputtering is an effective technique for producing ultrathin films with diverse applications. The review begins by providing an in-depth overview of the background, introducing the early development of sputtering and its principles. Consequently, progress in advancements made in recent decades highlights the renaissance of sputtering as a powerful technology for creating thin films with varied compositions, structures, and properties. For the first time, we have discussed a thorough overview of several sputtered thin film materials based on metal and metal oxide, metal nitride, alloys, carbon, and ceramic-based thin film along with their properties and their applicability in various fields. We further delve into the applications of sputter-coated thin films, specifically emphasizing their relevance in environmental sustainability, energy and electronics, and biomedical fields. We critically examine the recent advancements in developing sputter-coated catalysts for eliminating water pollutants andhydrogen generation. Additionally, the review sheds light on advantages, shortcomings, and future directions for developing sputter-coated thin films utilized in biodegradable metals and alloys with enhanced corrosion resistance and biocompatibility. This review is a comprehensive integration of recent literature, covering diverse sputtering thin film applications. We delve deeply into various material types and emphasize critical analysis of recent advancements, particularly in environmental, energy, and biomedical fields. By offering insights into both advancements and limitations, the review provides a nuanced understanding essential for practical utilization.

Multilevel neurium-mimetic individualized graft via additive manufacturing for efficient tissue repair

Complicated peripheral nerve injuries or defects, especially at branching sites, remain a prominent clinical challenge after the application of different treatment strategies. Current nerve grafts fail to match the expected shape and size for delicate and precise branched nerve repair on a case-by-case basis, and there is a lack of geometrical and microscale regenerative navigation. In this study, we develop a sugar painting-inspired individualized multilevel epi-/peri-/endoneurium-mimetic device (SpinMed) to customize natural cues, featuring a selectively protective outer sheath and an instructive core, to support rapid vascular reconstruction and consequent efficient neurite extension along the defect area. The biomimetic perineurium dictates host-guest crosslinking in which new vessels secrete multimerin 1 binding to the fibroin filler surface as an anchor, contributing to the biological endoneurium that promotes Schwann cell homing and remyelination. SpinMed implantation into rat sciatic nerve defects yields a satisfactory outcome in terms of structural reconstruction, with sensory and locomotive function restoration. We further customize SpinMed grafts based on anatomy and digital imaging, achieving rapid repair of the nerve trunk and branches superior to that achieved by autografts and decellularized grafts in a specific beagle nerve defect model, with reliable biosafety. Overall, this intelligent art-inspired biomimetic design offers a facile way to customize sophisticated high-performance nerve grafts and holds great potential for application in translational regenerative medicine.

Sulfated polysaccharide as biomimetic biopolymers for tissue engineering scaffolds fabrication: Challenges and opportunities

Sulfated polysaccharides play important roles in tissue engineering applications because of their high growth factor preservation ability and their native-like biological features. There are different sulfated polysaccharides based on different repeating units in the carbohydrate backbone, the position of the sulfate group, and the sulfation degree of the polysaccharide. These led to various sulfated polymers with different negative charge densities and resultant structure-property relationships. Since numerous reports are presented related to sulfated polysaccharide applications in tissue engineering, it is crucial to review the role of effective physicochemical and biological parameters in their usage; as well as their structure-property relationships. Within this review, we focused on the effect of naturally occurring and synthetic sulfated polysaccharides in tissue engineering applications reported in the last years, highlighting the challenges of the scaffold fabrication process, the position, and the degree of sulfate on biomedical activity. Additionally, we discussed their use in numerous in vitro and in vivo model systems.

Application and Development of Electrospun Nanofiber Scaffolds for Bone Tissue Engineering

Nanofiber scaffolds have gained significant attention in the field of bone tissue engineering. Electrospinning, a straightforward and efficient technique for producing nanofibers, has been extensively researched. When used in bone tissue engineering scaffolds, electrospun nanofibers with suitable surface properties promote new bone tissue growth and enhance cell adhesion. Recent advancements in electrospinning technology have provided innovative approaches for scaffold fabrication in bone tissue engineering. This review comprehensively examines the utilization of electrospun nanofibers in bone tissue engineering scaffolds and evaluates the relevant literature. The review begins by presenting the fundamental principles and methodologies of electrospinning. It then discusses various materials used in the production of electrospun nanofiber scaffolds for bone tissue engineering, including natural and synthetic polymers, as well as certain inorganic materials. The challenges associated with these materials are also described. The review focuses on novel electrospinning techniques for scaffold construction in bone tissue engineering, such as multilayer nanofibers, multifluid electrospinning, and the integration of electrospinning with other methods. Recent advancements in electrospinning technology have enabled the fabrication of precisely aligned nanofiber scaffolds with nanoscale architectures. These innovative methods also facilitate the fabrication of biomimetic structures, wherein bioactive substances can be incorporated and released in a controlled manner for drug delivery purposes. Moreover, they address issues encountered with traditional electrospun nanofibers, such as mechanical characteristics and biocompatibility. Consequently, the development and implementation of novel electrospinning technologies have revolutionized scaffold fabrication for bone tissue engineering.

[Construction of a novel tissue engineered meniscus scaffold based on low temperature deposition three-dimenisonal printing technology]

Objective

To investigate the construction of a novel tissue engineered meniscus scaffold based on low temperature deposition three-dimenisonal (3D) printing technology and evaluate its biocompatibility.

Methods

The fresh pig meniscus was decellularized by improved physicochemical method to obtain decellularized meniscus matrix homogenate. Gross observation, HE staining, and DAPI staining were used to observe the decellularization effect. Toluidine blue staining, safranin O staining, and sirius red staining were used to evaluate the retention of mucopolysaccharide and collagen. Then, the decellularized meniscus matrix bioink was prepared, and the new tissue engineered meniscus scaffold was prepared by low temperature deposition 3D printing technology. Scanning electron microscopy was used to observe the microstructure. After co-culture with adipose-derived stem cells, the cell compatibility of the scaffolds was observed by cell counting kit 8 (CCK-8), and the cell activity and morphology were observed by dead/live cell staining and cytoskeleton staining. The inflammatory cell infiltration and degradation of the scaffolds were evaluated by subcutaneous experiment in rats.

Results

The decellularized meniscus matrix homogenate appeared as a transparent gel. DAPI and histological staining showed that the immunogenic nucleic acids were effectively removed and the active components of mucopolysaccharide and collagen were remained. The new tissue engineered meniscus scaffolds was constructed by low temperature deposition 3D printing technology and it had macroporous-microporous microstructures under scanning electron microscopy. CCK-8 test showed that the scaffolds had good cell compatibility. Dead/live cell staining showed that the scaffold could effectively maintain cell viability (>90%). Cytoskeleton staining showed that the scaffolds were benefit for cell adhesion and spreading. After 1 week of subcutaneous implantation of the scaffolds in rats, there was a mild inflammatory response, but no significant inflammatory response was observed after 3 weeks, and the scaffolds gradually degraded.

Conclusion

The novel tissue engineered meniscus scaffold constructed by low temperature deposition 3D printing technology has a graded macroporous-microporous microstructure and good cytocompatibility, which is conducive to cell adhesion and growth, laying the foundation for the in vivo research of tissue engineered meniscus scaffolds in the next step.

Nonlinear Elasticity of Blood Vessels and Vascular Grafts

The transplantation of vascular grafts has emerged as a prevailing approach to address vascular disorders. However, the development of small-diameter vascular grafts is still in progress, as they serve in a more complicated mechanical environment than their counterparts with larger diameters. The biocompatibility and functional characteristics of small-diameter vascular grafts have been well developed; however, mismatch in mechanical properties between the vascular grafts and native arteries has not been accomplished, which might facilitate the long-term patency of small-diameter vascular grafts. From a point of view in mechanics, mimicking the nonlinear elastic mechanical behavior exhibited by natural blood vessels might be the state-of-the-art in designing vascular grafts. This review centers on elucidating the nonlinear elastic behavior of natural blood vessels and vascular grafts. The biological functionality and limitations associated with as-reported vascular grafts are meticulously reviewed and the future trajectory for fabricating biomimetic small-diameter grafts is discussed. This review might provide a different insight from the traditional design and fabrication of artificial vascular grafts.

Engineering Innervated Musculoskeletal Tissues for Regenerative Orthopedics and Disease Modeling

Musculoskeletal (MSK) disorders significantly burden patients and society, resulting in high healthcare costs and productivity loss. These disorders are the leading cause of physical disability, and their prevalence is expected to increase as sedentary lifestyles become common and the global population of the elderly increases. Proper innervation is critical to maintaining MSK function, and nerve damage or dysfunction underlies various MSK disorders, underscoring the potential of restoring nerve function in MSK disorder treatment. However, most MSK tissue engineering strategies have overlooked the significance of innervation. This review first expounds upon innervation in the MSK system and its importance in maintaining MSK homeostasis and functions. This will be followed by strategies for engineering MSK tissues that induce post-implantation in situ innervation or are pre-innervated. Subsequently, research progress in modeling MSK disorders using innervated MSK organoids and organs-on-chips (OoCs) is analyzed. Finally, the future development of engineering innervated MSK tissues to treat MSK disorders and recapitulate disease mechanisms is discussed. This review provides valuable insights into the underlying principles, engineering methods, and applications of innervated MSK tissues, paving the way for the development of targeted, efficacious therapies for various MSK conditions.

Distinct cellular microenvironment with cytotypic effects regulates orderly regeneration of vascular tissues

Regeneration of the architecturally complex blood vascular system requires precise temporal and spatial control of cell behaviours. Additional components must be integrated into the structure to achieve clinical success for in situ tissue engineering. Consequently, this study proposed a universal method for including any substrate type in vascular cell extracellular matrices (VCEM) via regulating selective adhesion to promote vascular tissue regeneration. The results uncovered that the VCEM worked as cell adhesion substrates, exhibited cell type specificity, and functioned as an address signal for recognition by vascular cells, which resulted in matching with the determined cells. The qPCR and immunofluorescence results revealed that a cell type-specific VCEM could be designed to promote or inhibit cell adhesion, consistenting with the expression patterns of eyes absent 3 (Eya3). In addition, a 3D vascular graft combined with VCEM which could recapitulate the vascular cell-like microenvironment was fabricated. The vascular graft revealed a prospective role for cellular microenvironment in the establishment of vascular cell distribution and tissue architecture, and potentiated the orderly regeneration and functional recovery of vascular tissues in vivo. The findings demonstrate that differential adhesion between cell types due to the cellular microenvironment is sufficient to drive the complex assembly of engineered blood vessel functional units, and underlies hierarchical organization during vascular regeneration.

Periapical lesion-derived decellularized extracellular matrix as a potential solution for regenerative endodontics

Pulp regeneration remains a crucial target in the preservation of natural dentition. Using decellularized extracellular matrix is an appropriate approach to mimic natural microenvironment and facilitate tissue regeneration. In this study, we attempted to obtain decellularized extracellular matrix from periapical lesion (PL-dECM) and evaluate its bioactive effects. The decellularization process yielded translucent and viscous PL-dECM, meeting the standard requirements for decellularization efficiency. Proteomic sequencing revealed that the PL-dECM retained essential extracellular matrix components and numerous bioactive factors. The PL-dECM conditioned medium could enhance the proliferation and migration ability of periapical lesion-derived stem cells (PLDSCs) in a dose-dependent manner. Culturing PLDSCs on PL-dECM slices improved odontogenic/angiogenic ability compared to the type I collagen group. In vivo, the PL-dECM demonstrated a sustained supportive effect on PLDSCs and promoted odontogenic/angiogenic differentiation. Both in vitro and in vivo studies illustrated that PL-dECM served as an effective scaffold for pulp tissue engineering, providing valuable insights into PLDSCs differentiation. These findings pave avenues for the clinical application of dECM's in situ transplantation for regenerative endodontics.

An endometrial biomimetic extracellular matrix (ECM) for enhanced endometrial regeneration using hyaluronic acid hydrogel containing recombinant human type III collagen

Endometrial injury poses a significant challenge in tissue regeneration, with type III collagen (COL III) playing a pivotal role in maintaining endometrial integrity and facilitating repair. Our study explored the utility of recombinant human type III collagen (RHC) as an intervention for endometrial damage. To address the challenges associated with the inherent instability and rapid degradation of COL III in vivo, we developed an RHC-HA hydrogel by conjugating RHC with hyaluronic acid (HA), thus ensuring a more stable and sustained delivery. Our findings suggested that the RHC-HA hydrogel significantly promoted endometrial regeneration and restored fertility. The hydrogel facilitated prolonged retention of RHC in the uterus, leading to a substantial improvement in the repair process. The synergistic interaction between RHC and HA greatly enhances cell proliferation and adhesion, surpassing the efficacy of HA or RHC alone. Additionally, the RHC-HA hydrogel demonstrated notable anti-fibrotic effects, which are crucial for preventing abnormalities during endometrial healing. These findings suggested that the RHC-HA hydrogel presented a therapeutic strategy in the treatment of uterine endometrial injuries, which may improve female reproductive health.

Exosome-loaded decellularized tissue: Opening a new window for regenerative medicine

Mesenchymal stem cell-derived exosomes (MSCs-EXO) have received a lot of interest recently as a potential therapeutic tool in regenerative medicine. Extracellular vesicles (EVs) known as exosomes (EXOs) are crucial for cell-cell communication throughout a variety of activities including stress response, aging, angiogenesis, and cell differentiation. Exploration of the potential use of EXOs as essential therapeutic effectors of MSCs to encourage tissue regeneration was motivated by success in the field of regenerative medicine. EXOs have been administered to target tissues using a variety of methods, including direct, intravenous, intraperitoneal injection, oral delivery, and hydrogel-based encapsulation, in various disease models. Despite the significant advances in EXO therapy, various methods are still being researched to optimize the therapeutic applications of these nanoparticles, and it is not completely clear which approach to EXO administration will have the greatest effects. Here, we will review emerging developments in the applications of EXOs loaded into decellularized tissues as therapeutic agents for use in regenerative medicine in various tissues.

Recent advances in enhances peripheral nerve orientation: the synergy of micro or nano patterns with therapeutic tactics

Several studies suggest that topographical patterns influence nerve cell fate. Efforts have been made to improve nerve cell functionality through this approach, focusing on therapeutic strategies that enhance nerve cell function and support structures. However, inadequate nerve cell orientation can impede long-term efficiency, affecting nerve tissue repair. Therefore, enhancing neurites/axons directional growth and cell orientation is crucial for better therapeutic outcomes, reducing nerve coiling, and ensuring accurate nerve fiber connections. Conflicting results exist regarding the effects of micro- or nano-patterns on nerve cell migration, directional growth, immunogenic response, and angiogenesis, complicating their clinical use. Nevertheless, advances in lithography, electrospinning, casting, and molding techniques to intentionally control the fate and neuronal cells orientation are being explored to rapidly and sustainably improve nerve tissue efficiency. It appears that this can be accomplished by combining micro- and nano-patterns with nanomaterials, biological gradients, and electrical stimulation. Despite promising outcomes, the unclear mechanism of action, the presence of growth cones in various directions, and the restriction of outcomes to morphological and functional nerve cell markers have presented challenges in utilizing this method. This review seeks to clarify how micro- or nano-patterns affect nerve cell morphology and function, highlighting the potential benefits of cell orientation, especially in combined approaches.

Chitin microspheres: From fabrication to applications

Chitin microspheres (CMs) have attracted increasing attention due to their biocompatibility, uniform size and shape, large surface area, and porous structure. Considerable research efforts have been focused on developing CMs and promoting their applications in various areas. In this context, this review aims to describe the most recent progress in the fabrication and application of CMs. Different routes that can be used to prepare CMs, such as the drip method and the emulsion method, are emphatically introduced. Moreover, the applications of CMs as drug delivery systems, wound dressings, three-dimensional (3D) scaffolds, water purification, and functional supporting materials in the fields of biomedicine, tissue engineering, environmental protection, and energy storage are also highlighted. We hope this review can provide a comprehensive and useful database for further innovation of CMs.

Perspectives on the Novel Multifunctional Nerve Guidance Conduits: From Specific Regenerative Procedures to Motor Function Rebuilding

Peripheral nerve injury potentially destroys the quality of life by inducing functional movement disorders and sensory capacity loss, which results in severe disability and substantial psychological, social, and financial burdens. Autologous nerve grafting has been commonly used as treatment in the clinic; however, its rare donor availability limits its application. A series of artificial nerve guidance conduits (NGCs) with advanced architectures are also proposed to promote injured peripheral nerve regeneration, which is a complicated process from axon sprouting to targeted muscle reinnervation. Therefore, exploring the interactions between sophisticated NGC complexes and versatile cells during each process including axon sprouting, Schwann cell dedifferentiation, nerve myelination, and muscle reinnervation is necessary. This review highlights the contribution of functional NGCs and the influence of microscale biomaterial architecture on biological processes of nerve repair. Progressive NGCs with chemical molecule induction, heterogenous topographical morphology, electroactive, anisotropic assembly microstructure, and self-powered electroactive and magnetic-sensitive NGCs are also collected, and they are expected to be pioneering features in future multifunctional and effective NGCs.

Extracellular Matrix Interactome in Modulating Vascular Homeostasis and Remodeling

The ECM (extracellular matrix) is a major component of the vascular microenvironment that modulates vascular homeostasis. ECM proteins include collagens, elastin, noncollagen glycoproteins, and proteoglycans/glycosaminoglycans. ECM proteins form complex matrix structures, such as the basal lamina and collagen and elastin fibers, through direct interactions or lysyl oxidase-mediated cross-linking. Moreover, ECM proteins directly interact with cell surface receptors or extracellular secreted molecules, exerting matricellular and matricrine modulation, respectively. In addition, extracellular proteases degrade or cleave matrix proteins, thereby contributing to ECM turnover. These interactions constitute the ECM interactome network, which is essential for maintaining vascular homeostasis and preventing pathological vascular remodeling. The current review mainly focuses on endogenous matrix proteins in blood vessels and discusses the interaction of these matrix proteins with other ECM proteins, cell surface receptors, cytokines, complement and coagulation factors, and their potential roles in maintaining vascular homeostasis and preventing pathological remodeling.