Objective:To construct a temperature-sensitive hydrogel (PF-CA@AS-IV hydrogel) composed of Pluronic F-127 (PF-127)/calcium alginate (CA) loaded with astragaloside IV (AS-IV), and to explore its repair effect and potential mechanism on diabetic skin ulcers (DSU).Methods:The PF-CA@AS-IV hydrogel loaded with AS-IV and gelling at 37 ℃ was prepared. Its temperature sensitivity, rheological properties, and morphology were characterized. A rat model of DSU was established, and the rats were randomly divided into blank control group, model group, AS-IV spray group, PF-CA hydrogel group, and PF-CA@AS-IV hydrogel group ( n=5 each). After 21 days of intervention, the wound healing rate of each group was evaluated. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of granulation tissue, and immunohistochemistry was applied to detect the expression level of CD34, a marker of new blood vessels. Results:Rheological analysis showed that the storage modulus (G′) of PF-CA@AS-IV hydrogel began to exceed the loss modulus (G″) at 33 ℃, and a stable three-dimensional network structure was formed at 37 ℃. Scanning electron microscopy confirmed its loose and porous microstructure. Animal experiment results indicated that compared with the blank control group, the model group had a significantly lower wound healing rate, massive infiltration of inflammatory cells, and fewer new capillaries and CD34 expression (all P<0.05). Compared with the model group, each treatment group can promote wound healing, reduce inflammatory infiltration and increase the positive expression of CD34 to varying degrees (all P<0.05), and the curative effect of PF-CA@AS-IV hydrogel group is the most significant, which is better than that of AS-IV spray group and PF-CA hydrogel group (all P<0.05). Conclusions:PF-CA@AS-IV hydrogel can effectively regulate inflammatory response and promote angiogenesis through sustained release of AS-IV, thereby accelerating DSU healing, and has good translational potential in the field of chronic wound repair.

Objective:To construct a temperature-sensitive hydrogel (PF-CA@AS-IV hydrogel) composed of Pluronic F-127 (PF-127)/calcium alginate (CA) loaded with astragaloside IV (AS-IV), and to explore its repair effect and potential mechanism on diabetic skin ulcers (DSU).Methods:The PF-CA@AS-IV hydrogel loaded with AS-IV and gelling at 37 ℃ was prepared. Its temperature sensitivity, rheological properties, and morphology were characterized. A rat model of DSU was established, and the rats were randomly divided into blank control group, model group, AS-IV spray group, PF-CA hydrogel group, and PF-CA@AS-IV hydrogel group ( n=5 each). After 21 days of intervention, the wound healing rate of each group was evaluated. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of granulation tissue, and immunohistochemistry was applied to detect the expression level of CD34, a marker of new blood vessels. Results:Rheological analysis showed that the storage modulus (G′) of PF-CA@AS-IV hydrogel began to exceed the loss modulus (G″) at 33 ℃, and a stable three-dimensional network structure was formed at 37 ℃. Scanning electron microscopy confirmed its loose and porous microstructure. Animal experiment results indicated that compared with the blank control group, the model group had a significantly lower wound healing rate, massive infiltration of inflammatory cells, and fewer new capillaries and CD34 expression (all P<0.05). Compared with the model group, each treatment group can promote wound healing, reduce inflammatory infiltration and increase the positive expression of CD34 to varying degrees (all P<0.05), and the curative effect of PF-CA@AS-IV hydrogel group is the most significant, which is better than that of AS-IV spray group and PF-CA hydrogel group (all P<0.05). Conclusions:PF-CA@AS-IV hydrogel can effectively regulate inflammatory response and promote angiogenesis through sustained release of AS-IV, thereby accelerating DSU healing, and has good translational potential in the field of chronic wound repair.