INS and renal fibrosis: Masson staining revealed renal tissue in red and the collagen fibers in blue in DKD group (Figure 5(b)) and PAS staining revealed a significant increase in glomerular glycogen deposition in the DKD group (Figure 5(c)), indicated that renal fibrosis and injury in DKD mice were more serious than the normal controls, but alleviated in the MSCs-Exo transplantation and insulin treatment groups compared with the DKD groups.