The application of composite scaffold materials based on decellularized vascular matrix in tissue engineering: a review

ECM-mimetic glucomannan hydrogel promotes pressure ulcer healing by scavenging ROS, promoting angiogenesis and regulating macrophages

Pressure ulcers (PUs) have emerged as a significant burden on both individuals and society. Effective treatment of PUs is a significant clinical challenge due to the compromised tissue microenvironment characterized by extracellular matrix (ECM) depletion, increased levels of reactive oxygen species (ROS), excessive inflammation and impaired angiogenesis. To this end, we have developed a glucomannan hydrogel (GM-Pgel) that mimics the skin's extracellular matrix to accelerate wound healing by regulating chronic inflammation in the PUs. This hydrogel not only faithfully replicates the components and nanofibrous architecture of ECM-like glycoproteins but also exhibits remarkable capabilities in enhancing neovascularization, scavenging ROS, and promoting macrophage polarization toward the M2 phenotype. In summary, this ECM-mimetic multifunctional hydrogel emerges as a promising dressing with diverse functionalities, capable of reshaping the compromised tissue environment without the need for additional drugs, exogenous cytokines, or cells. This presents a compelling and effective strategy for the repair and regeneration of chronic cutaneous wounds.

Polyzwitterion-grafted decellularized bovine intercostal arteries as new substitutes of small-diameter arteries for vascular regeneration

Coronary artery bypass grafting is acknowledged as a major clinical approach for treatment of severe coronary artery atherosclerotic heart disease. This procedure typically requires autologous small-diameter vascular grafts. However, the limited availability of the donor vessels and associated trauma during tissue harvest underscore the necessity for artificial arterial alternatives. Herein, decellularized bovine intercostal arteries were successfully fabricated with lengths ranging from 15 to 30 cm, which also closely match the inner diameters of human coronary arteries. These decellularized arterial grafts exhibited great promise following poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) grafting from the inner surface. Such surface modification endowed the decellularized arteries with superior mechanical strength, enhanced anticoagulant properties and improved biocompatibility, compared to the decellularized bovine intercostal arteries alone, or even those decellularized grafts modified with both heparin and vascular endothelial growth factor. After replacement of the carotid arteries in rabbits, all surface-modified vascular grafts have shown good patency within 30 days post-implantation. Notably, strong signal was observed after α-SMA immunofluorescence staining on the PMPC-grafted vessels, indicating significant potential for regenerating the vascular smooth muscle layer and thereby restoring full structures of the artery. Consequently, the decellularized bovine intercostal arteries surface modified by PMPC can emerge as a potent candidate for small-diameter artificial blood vessels, and have shown great promise to serve as viable substitutes of arterial autografts.

Synthesis and characterization of chitosan/collagen/polycaprolactone hydrogel films with enhanced biocompatibility and hydrophilicity for artificial tendon applications

Regenerative medicine confronts various obstacles, such as creating and advancing biomaterials. Besides being safe, such materials should promote cellular activity. Polycaprolactone (PCL) has numerous medical applications as an engineering material. However, these polymers lack hydrophilicity. Herein, chitosan (CS)/collagen (COL)/polycaprolactone hydrogel films (CSCPs) were synthesized with different weight ratios of PCL; specifically, CS/COL (CSC): PCL content of 1:3, 1:6, and 1:9. For this purpose, novel COL immobilization on CS was performed via covalent attachment. Following the addition of PCL to CSC hydrogel, the resulting CSCP hydrogel films were characterized using tensile measurements, TGA, XRD, FTIR, and FE-SEM. A greater PCL content increases the elongation at break from 134.8 to 369.5 % and the tensile strength of the hydrogel films from 4.8 to 18.4 MPa. The hydrophobicity of prepared specimens was assessed through water absorption and contact-angle tests. For CSCP3 to CSCP9, the water contact angle increased from 61.03° to 70.82°. After 48 days, CSCP6 and CSCP9 hydrogel films demonstrated a slow rate of degradation, losing <15 % of their weight. Moreover, all three types of hydrogel films exhibited high biocompatibility (higher than 95 % after three days), as confirmed by the MTT assay. The hemolysis rates of CSCP hydrogel films were <2 %, which could be deemed safe for contact with a blood environment. The presence of no costly and bio-based crosslinking agents and desired characteristics for tissue engineering applications suggest that CSCP hydrogel films may be promising candidates for use in artificial tendons.

Biomedical Application of Decellularized Scaffolds

Tissue loss and end-stage organ failure are serious health problems across the world. Natural and synthetic polymer scaffold material based artificial organs play an important role in the field of tissue engineering and organ regeneration, but they are not from the body and may cause side effects such as rejection. In recent years, the biomimetic decellularized scaffold based materials have drawn great attention in the tissue engineering field for their good biocompatibility, easy modification, and excellent organism adaptability. Therefore, in this review, we comprehensively summarize the application of decellularized scaffolds in tissue engineering and biomedicine in recent years. The preparation methods, modification strategies, construction of artificial tissues, and application in biomedical applications are discussed. We hope that this review will provide a useful reference for research on decellularized scaffolds and promote their application tissue engineering.

Exploring the interaction between extracellular matrix components in a 3D organoid disease model to replicate the pathophysiology of breast cancer

In vitro models are necessary to study the pathophysiology of the disease and the development of effective, tailored treatment methods owing to the complexity and heterogeneity of breast cancer and the large population affected by it. The cellular connections and tumor microenvironments observed in vivo are often not recapitulated in conventional two-dimensional (2D) cell cultures. Therefore, developing 3D in vitro models that mimic the complex architecture and physiological circumstances of breast tumors is crucial for advancing our understanding of the illness. A 3D scaffold-free in vitro disease model mimics breast cancer pathophysiology by allowing cells to self-assemble/pattern into 3D structures, in contrast with other 3D models that rely on artificial scaffolds. It is possible that this model, whether applied to breast tumors using patient-derived primary cells (fibroblasts, endothelial cells, and cancer cells), can accurately replicate the observed heterogeneity. The complicated interactions between different cell types are modelled by integrating critical components of the tumor microenvironment, such as the extracellular matrix, vascular endothelial cells, and tumor growth factors. Tissue interactions, immune cell infiltration, and the effects of the milieu on drug resistance can be studied using this scaffold-free 3D model. The scaffold-free 3D in vitro disease model for mimicking tumor pathophysiology in breast cancer is a useful tool for studying the molecular basis of the disease, identifying new therapeutic targets, and evaluating treatment modalities. It provides a more physiologically appropriate high-throughput platform for screening large compound library in a 96-384 well format. We critically discussed the rapid development of personalized treatment strategies and accelerated drug screening platforms to close the gap between traditional 2D cell culture and in vivo investigations.

Modification of the Human Amniotic Membrane Using Different Cross-Linking Agents as a Promising Tool for Regenerative Medicine

Human amniotic membranes (hAMs) obtained during cesarean sections have proven to be clinically useful as an interesting biomaterial in a wide range of tissue engineering applications such as ocular surface reconstruction, burn treatments, chronic wounds, or bedsore ulcers. It presents antimicrobial properties, promotes epithelization, reduces inflammation and angiogenesis, contains growth factors, and constitutes the reservoir of stem cells. However, variability in hAM stiffness and its fast degradation offers an explanation for the poor clinical applications and reproducibility. In addition, the preparatory method of hAM for clinical use can affect its mechanical properties, and these differences can influence its application. As a directly applied biomaterial, the hAM should be available in a ready-to-use manner in clinical settings. In the present study, we performed an analysis to improve the mechanical properties of hAM by the addition of various reagents used as protein cross-linkers: EDC/NHS, PEG-dialdehyde, PEG-NHS, dialdehyde starch, and squaric acid. The effect of hAM modification using different cross-linking agents was determined via infrared spectroscopy, thermal analyses, mechanical properties analyses, enzymatic degradation, and cytotoxicity tests. The use of PEG-dialdehyde, PEG-NHS, dialdehyde starch, and squaric acid increases the mechanical strength and elongation at the breaking point of hAM, while the addition of EDC/NHS results in material stiffening and shrinkage. Also, the thermal stability and degradation resistance were evaluated, demonstrating higher values after cross-linking. Overall, these results suggest that modification of human amniotic membrane by various reagents used as protein cross-linkers may make it easier to use hAM in clinical applications, and the presented study is a step forward in the standardization of the hAM preparation method.