Investigation on repairing diabetic foot ulcer based on 3D bio-printing Gel/dECM/Qcs composite scaffolds

Diabetic foot ulcers are one of the most serious of the numerous complications of diabetes mellitus, causing great physical trauma and financial stress to patients, and accelerating wound healing in diabetic patients remains one of the major clinical challenges. Exosomes from adipose-derived stem cells can directly and indirectly promote wound healing. However, due to the low retention rate of exosomes in the wound, exosome treatment is difficult to achieve the expected effect. Therefore, it is of great significance to synthesize a composite scaffold that can stably load exosomes and has antibacterial properties. In this study, fresh pig skin was decellularized to obtain decellularized matrix (dECM). Secondly, quaternized chitosan (Qcs) was modified with quaternary ammonium salt to make it soluble in water after quaternization. Finally, Gel-dECM-Qcs (GDQ) bioink was prepared by adding acellular matrix and quaternized chitosan with temperature sensitive gelatin (Gel) as carrier. Tissue engineered composite scaffolds were then prepared by extrusion 3D printing technology. Subsequently, the physicochemical properties, biocompatibility and antimicrobial capacity of the composite scaffolds were determined, and the data showed that the composite scaffolds had good mechanical properties, biocompatibility and antimicrobial capacity, and the maximum stress of the composite scaffolds was 1.16 ± 0.05 MPa, the composite scaffolds were able to proliferate and adhered to the L929 cells, and the kill rates of composite scaffolds against E. coli and S. aureus after incubation for 24 h were 93.24 ± 1.22 % and 97.34 ± 0.23 %, respectively. Overall, the GDQ composite scaffolds have good mechanical properties adapted to skin bending, its good biocompatibility can promote the growth and migration of fibroblasts, reshape injured tissues, accelerate the wound healing, and excellent antimicrobial ability can inhibit the growth of E. coli and S. aureus, reducing the impact of bacterial infections on wounds. Moreover, the composite scaffolds have the potential to be used as exosom-loaded hydrogel dressings, which provides a basis for the subsequent research on the repair of diabetic foot ulcers.