Abstract: Objective To investigate the preparation of chitosan (CS) temperature-sensitive gel loaded with human platelet lysate (HPL), and to verify its repairing effect in refractory wounds in high-altitude diabetic rats. Methods The ratio of CS and HPL was adjusted, and the optimal preparation conditions of HPL-CS temperature-sensitive gel were determined by apparent and electron microscopy observation, and the gel formation was observed at different temperatures. SD rats were divided into plain group and plateau group, and then randomly divided into control group, model group, CS group and HPL-CS group. There was no treatment in the control group, only modeling was done in the diabetic group, CS gel was applied daily in the CS group, and HPL-CS temperature sensitive gel was applied daily in the HPL-CS group. The wound healing of each group was compared at day 0, 3, 7, 14 and 21, and samples were collected at day 7, 14 and 21 for Hematoxylin-Eosin staining (H&E)and Masson staining. Results HPL:CS=1:1 was the optimal ratio to prepare of HPL-CS gel. HPL-CS temperature-sensitive gel formed a gel at 37 ℃, and the liquid precipitated at 22 ℃, but the liquid state could not be completely restored. The wound healing rate in HPL-CS group was higher than that in Model group and in the CS group at all time points, no matter in plain group or plateau group. Pathological results showed that the HPL-CS group had fewer inflammatory cells, more epithelial cells, more tightly arranged collagen fibers, and much more neovascularization compared with the other groups. Conclusion HPL-CS temperature-sensitive gel can significantly improve the repair effect of diabetes refractory wounds in high-altitude environment.

Key words: HPL-CS hydrogel, Diabetic refractory wounds, High-altitude environment, Thermosensitivity, Growth factor