INS and type 1 diabetes mellitus: Relative to the insulin-treated mice, a more pronounced reduction in islet cell apoptosis with relatively increased cell proliferation was seen in the pancreatic tissues of T1DM mice treated with exenatide, hUCMSCs, or hUCMSCs@Ex-4, of which hUCMSCs@Ex-4 resulted in the most obvious changes (Fig. 2I, J).