Biomimetic SIS-based biocomposites with improved biodegradability, antibacterial activity and angiogenesis for abdominal wall repair

Small intestinal submucosa (SIS) is a widely concerned acellular material for reconstructing tissue defects, but during the restoration of abdominal wall, it has been restricted due to the fast degradation causing poor long-term mechanical properties, the infection caused by bacteria contamination, and insufficient neovascularization post-operation. In this study, we developed a biomimetic SIS-based biocomposite (CS/ES-SIS) for abdominal wall repair, in which chitosan (CS) and elastin (ES) electrospun nanofibers were used to improve the biodegradability, antibacterial activity, and angiogenesis. The CS/ES-SIS composites were examined through a series of testing experiments, especially in vitro degradation was assessed by a constant deformation loading device and the micromechanical properties during enzymatic degradation under biomechanical environment were measured by nanoindentation. In vitro antibacterial test and cytocompatibility, and in vivo biocompatibility, neovascularisation and tissue regeneration were also investigated. The main research results as follows: (1) After 7 days enzymatic degradation under biomechanical environment, the degradation rate of CS/ES-SIS composites was slower than that of SIS by about 24.5%. Moreover, the CS/ES-SIS composites could better maintain the stability of microstructure and micromechanical properties compared with SIS. (2) The antibacterial rates of CS/ES-SIS composites against E. coli and S. aureus were respectively 98.87% and 98.26% while the SIS demonstrated no obvious antibacterial capacity. (3) The CS/ES-SIS composites supported the viability and proliferation of fibroblast cell L929. In vivo studies showed that the CS/ES-SIS composites could promote tissue regeneration upon implantation without serious inflammatory reaction. Additionally, the vascular number in the CS/ES-SIS composites was as 1.69 times as that in the SIS at 4 weeks. Collectively, all the findings suggested that the newly developed CS/ES-SIS composites might be promising and attractive candidates for applications of abdominal wall repair.