Effect of earthworm oil on formation of collagen type III during wound healing process in BALB/c mice

Introduction: Eisenia fetida is a species of earthworm. The oil extracted from this species has been found to have antimicrobial and antioxidant characteristics as well as omega-3, omega-6, and omega-9 fatty acids in its contents. The regenerative properties of this compound are very impressive. Aim: This study aimed to evaluate the effect of earthworm oil on wound healing based on collagen type III formation in the BALB/c mice. Materials and methods: The present experimental study was conducted in Birjand, Iran, in 2019. Forty-eight male adults BALB/c mice were divided into 4 groups (12 mice in each group). The intervention group received earthworm oil, the negative and positive control groups received sesame oil and 1% nitrofurazone cream, respectively, whereas the sham group received no treatment at al. A full-thickness excision wound with a 5-mm disposable surgical punch was made on the dorsal skin of all mice after anesthesia. The wounds in groups 1, 2, and 3 were dressed twice a day. At days 4, 7, 10, and 14 after wounding, excisional biopsy was performed and the sample was examined histologically and immunohistochemically using the ImageJ software. Data were analysed by ANOVA and Tukey tests using SPSS software version 22. Results: In the tissue samples treated with earthworm oil, the number of fibroblast cells and granulation tissue formation and epithelialization significantly increased; the thickness of type III collagen fibers in this group predominantly increased in comparison to other control groups. Conclusions: This study has demonstrated that the earthworm oil has a positive effect on the wound healing process, especially by promoting the collagen synthesis.