Abstract:

Objective To prepare a novel ginseng polypeptide thermosensitive hydrogel， and to investigate its repair effect on heat-induced skin injury in the rats and explore the underlying mechanisms. Methods Thermosensitive hydrogels were formulated using Pluronic F127 and β-sodium glycerophosphate（β-GP）， and their phase transition temperatures， spatial structures， elemental compositions， and water retention capacities were evaluated. The rat models of heat-induced skin injury were established and the model rats were divided into PBS group， Gel group， and ginseng polypeptide gel （GP-Gel） group. After 11 d of treatment， the morphological changes of wound and collagen deposition in the wound of the rats in various groups were observed by HE and Masson staining. Immunohistochemistry was used to detect the expression levels of α-smooth muscle actin （α-SMA）， connective tissue growth factor （CTGF）， basic fibroblast growth factor （bFGF）， proliferating cell nuclear antigen （PCNA）， cell proliferation marker Ki67， epidermal growth factor （EGF）， CD31， vascular endothelial growth factor （VEGF）， P50 and P65 proteins in the skin wound tissue of the rats in various groups. Western blotting method was used to detect the expression levels of Toll-like receptor 4 （TLR4） in the skin wound tissue of the rats in various groups. ELISA method was used to measure the levels of tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， interleukin-6 （IL-6）， interleukin-15 （IL-15）， and interleukin-10 （IL-10） in the serum of the rats in various groups. Results Compared with PBS and Gel groups， the wound area of the rats in GP-Gel group was reduced（P<0.01）， the expression levels of PCNA， Ki67， EGF， CD31， VEGF， α-SMA， and CTGF proteins in the skin wound tissue were increased （P<0.05 or P<0.01）， and the expression levels of P65 and TLR4 proteins were decreased （P<0.01）； the level of anti-inflammatory factor IL-10 in serum was increased （P<0.01）， while the levels of pro-inflammatory factors TNF-α， IL-1β， IL-6 and IL-15 were decreased （P<0.05 or P<0.01）. Conclusion The ginseng polypeptide thermosensitive hydrogel promotes the repair of heat-induced skin injury by enhancing cell proliferation， collagen synthesis， angiogenesis， and reducing inflammatory responses.

Key words: Ginseng polypeptide, Hydrogel, Heat-induced skin injury, Inflammation, Angiogenesis