[Effect of salvia miltiorrhiza combined with roxadustat on wound healing of full-thickness skin defects in diabetic rats and its mechanism].

Objective: To explore the effect of salvia miltiorrhiza combined with roxadustat on wound healing of full-thickness skin defects in diabetic rats and its mechanism. Methods: This study was an experimental study. Twenty male 8-week-old Sprague-Dawley rats were used to successfully establish diabetic model, then full-thickness skin defect wounds on their backs were made. The rats were divided into normal saline group, roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group according to the random number table, with 5 rats in each group. Immediately after injury, the rats in normal saline group were given 5 mL normal saline by gavage, the rats in roxadustat alone group were given 1.5 mg/mL roxadustat suspension by gavage at 25 mg/kg, the rats in salvia miltiorrhiza alone group were given 18 mg/mL salvia miltiorrhiza suspension by gavage at 300 mg/kg, and the rats in roxadustat+salvia miltiorrhiza group were given 19.5 mg/mL roxadustat and salvia miltiorrhiza suspension at roxadustat 25 mg/kg and salvia miltiorrhiza 300 mg/kg. All were administered once a day for 2 weeks. The wounds at 0 (immediately), 4, 8, and 12 d after injury were observed, and the wound healing rates at 4, 8, and 12 d after injury were calculated (n=5). At 14 d after injury, abdominal aortic blood was collected, and hemoglobin, red cell count, and white blood cell count were detected (n=5). The wound tissue was collected for hematoxylin-eosin staining to observe inflammatory infiltration, skin tissue structure, and neovascularization, for Masson staining to observe the proportion of collagen fiber (n=3), for Western blotting to detect the protein expression levels of vascular endothelial growth factor (VEGF), CD31, interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and IL-1β (n=3), and for immunohistochemical staining to determine the protein expression levels of epidermal growth factor receptor (EGFR), hypoxia-inducible factor 1α (HIF-1α), and proliferating cell nuclear antigen (PCNA), with sample number of 3. Results: From 0 to 12 d after injury, the wound areas of rats in 4 groups were gradually decreased. At 4 d after injury, the wound healing rates of rats in salvia miltiorrhiza alone group and roxadustat+salvia miltiorrhiza group were significantly higher than those in normal saline group and roxadustat alone group (P<0.05). At 8 d after injury, the wound healing rates of rats in roxadustat alone group and salvia miltiorrhiza alone group were significantly higher than the rate in normal saline group (P<0.05), and the wound healing rate of rats in roxadustat+salvia miltiorrhiza group was significantly higher than the rates in the other 3 groups (with P values all <0.05). At 12 d after injury, the wound healing rates of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were significantly higher than the rate in normal saline group (P<0.05). At 14 d after injury, there were no statistically significant differences in the hemoglobin or red blood cell count of rats in 4 groups (P<0.05). The white blood cell count of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were respectively (24.3±1.2)×109/L, (26.3±2.4)×109/L, and (15.0±0.7)×109/L, which were significantly lower than (33.8±2.7)×109/L in normal saline group (P<0.05); the white blood cell count of rats in roxadustat+salvia miltiorrhiza group was significantly lower than that in roxadustat alone group and salvia miltiorrhiza alone group (with P values both <0.05). At 14 d after injury, a large number of inflammatory cell infiltration, disordered skin tissue structure, and few new blood vessels were observed in the wounds of rats in normal saline group; while a small amount of inflammatory cell infiltration, tight skin tissue structure, and rich neovascularization were observed in the wounds of rats in the other 3 groups. There were no statistically significant differences in the proportion of collagen fiber of wounds in rats among the 4 groups (P>0.05). At 14 d after injury, the protein expression levels of VEGF and CD31 in the wound tissue of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were significantly higher than those in normal saline group (P<0.05), the protein expression level of CD31 in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly higher than the levels in roxadustat alone group and salvia miltiorrhiza alone group (with P values both <0.05). At 14 d after injury, the protein expression levels of IL-6, TNF-α, and IL-1β in the wound tissue of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were significantly lower than those in normal saline group (P<0.05); the protein expression levels of IL-6 and IL-1β in the wound tissue of rats in roxadustat+salvia miltiorrhiza group were significantly lower than those in roxadustat alone group and salvia miltiorrhiza alone group (P<0.05); the protein expression level of TNF-α in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly lower than that in salvia miltiorrhiza alone group (P<0.05). At 14 d after injury, the protein expression level of EGFR in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly higher than the levels in the other 3 groups (with P values all <0.05); the protein expression levels of HIF-1α in the wound tissue of rats in roxadustat alone group and roxadustat+salvia miltiorrhiza group were significantly higher than the level in normal saline group (P<0.05), and the protein expression level of HIF-1α in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly higher than that in salvia miltiorrhiza alone group (P<0.05); there were no statistically significant differences in the protein expression level of PCNA in the wound tissue of rats in 4 groups (P>0.05). Conclusions: Roxadustat combined with salvia miltiorrhiza can promote the wound healing of full-thickness skin defects in diabetic rats by promoting blood vessel regeneration and reducing inflammatory response.