WT1 and diabetic kidney disease: In addition, immunohistochemical staining showed that the number of cells positive for the podocyte nuclear marker WT1 was significantly decreased in the DKD group, while the number of podocytes increased after the hucMSC-sEVs intervention, which alleviated the podocyte loss that occurred during the DKD period (Figures 2(e) and 2(f)).