The therapeutic effects of earthworm extract on deep second-degree burn wound healing

Background: To investigated the effect of earthworm extract (EE) on deep second-degree burn wound healing process. Methods: A burn wound model was created on the mice's skin and was subject to different treatments: the control group received no treatment; the Jingwanhong (JWH: a well-established, widely used external ointment for treating burn wounds) group was treated with 0.1 g of JWH cream and spray it on the wound surface; the EE group was treated with 0.1 mL of EE solution. All the mice were sacrificed at 3, 7, 11, and 15 days after injury (n=6/group/time point). Macroscopic observation, wound healing rate (WHR), wound healing time (WHT), water content (WC), hydroxyproline (Hyp) content, histological, and hematological analyses were performed at the burn wound sites. Results: Better, faster burn wound healing in the JWH and EE groups than the control group at 15 days after injury were detected at the wound sites. Compared to the control group, the EE group had higher WHR, shorter WHT, lower WC, higher Hyp content, more fibroblasts, fibrocytes, and capillary endothelial cells; in addition, they showed greater capillary endothelial cell grouping at the wound sites during the healing process. This group also showed more platelets, white blood cells (WBCs), and neutrophilic granulocytes in serum at the early stages after burn injury. Conclusions: EE could effectively promote skin wound healing by decreasing edema, suppressing fibrosis, activating angiogenesis and epithelial regeneration, inhibiting scar formation, and reducing the risk of infection. Thus, it could be made into a promising healing agent for burn wound.