Compared with the C57BL/6J mice, the T2DM mice injected with PBS and those injected with MSC-sEVs and Ap-MSC-sEVs exhibited a significant increase in the number of insulin-positive and Ki-67-positive cells within the islets, which suggested that the increased replication of β-cells likely drove the enlargement of the β-cell area (Fig. 5b) (P < 0.05). The gene discussed is MKI67; the disease is type 2 diabetes mellitus.