Additionally, the results of Masson staining indicated increased collagen deposition and thickened wavy collagen fibers in the DM rats treated with exosomes compared to PBS-treated DM rats on day 14; however, treatment with IRF1-exosome led to more collagen deposition than treatment with exosomes, and the arrangement of wavy collagen fibers was similar to normal skin (Fig. 6E). The gene discussed is IRF1; the disease is diabetes mellitus.