Comparison between the therapeutic effects of differentiated and undifferentiated Wharton's jelly mesenchymal stem cells in rats with streptozotocin-induced diabetes

Figure 1 Morphology of undifferentiated human Wharton's jelly mesenchymal stem cells and islet-like clusters differentiated from human Wharton's jelly mesenchymal stem cells. A: Undifferentiated spindle-shaped human Wharton's jelly mesenchymal stem cells (20 ×); B: Islet-like clusters after differentiation (20 ×); C: Dithizone-positive cells, which represent insulin-secreting cells (20 ×); D-G: Immunofluorescence staining with anti-insulin antibodies (green) and anti-human-nuclei antibodies (red) (40 ×).

Figure 2 Comparison of serum C-peptide concentration and insulin concentration between undifferentiated human Wharton's jelly mesenchymal stem cells and insulin-producing cells in response to glucose stimulation. Differentiated insulin-producing cells (IPCs) secreted significant amounts of C-peptide and insulin, whereas undifferentiated human Wharton's jelly mesenchymal stem cells (MSCs) secreted lower amounts. ^aP < 0.05 when comparing the concentration of C-peptide and insulin by differentiated insulin-producing cells in response to the higher glucose (HG) and lower glucose (LG) environments.

Figure 3 Comparison of differences in blood glucose, serum insulin, serum C-peptide, and intraperitoneal glucose tolerance test results between streptozotocin-induced diabetic rats treated with undifferentiated human Wharton's jelly mesenchymal stem cells and insulin-producing cells. A: ^aP < 0.05, compared to the normal saline (NS) treatment group, the rats in the two treatment groups had significantly decreased blood glucose levels; ^cP < 0.05, blood glucose levels in rats in the insulin-producing cell (IPC) group were significantly lower than in rats from the undifferentiated human Wharton’s jelly mesenchymal stem cell (hWJ-MSC) group; B: ^aP < 0.05, compared to the NS treatment group, the rats in other two treatment groups had significantly higher serum insulin levels; ^cP < 0.05, serum insulin levels in rats from the IPC group were significantly higher than those in rats from the undifferentiated hWJ-MSC group; ^aP < 0.05, compared to the NS treatment group, rats in the IPC treatment group had significantly higher serum C-peptide levels; ^cP < 0.05, serum C-peptide level blood glucose level of rats from the IPC group was significantly higher than those in rats from the undifferentiated hWJ-MSC group; C: IPC and MSC treatment led to better improvement in the intraperitoneal glucose tolerance test (IPGTT) result than NS treatment in both the first and eighth weeks.

Figure 4 Comparison of the serum cytokine profile in the different treatment groups of diabetic rats. ^aP < 0.05, P < 0.05 when compared with the serum concentration of the normal saline (NS) group. ^cP < 0.05, P < 0.05 when comparing the serum concentration between the mesenchymal stem cell (MSC) group and insulin-producing cell (IPC) group. NS: Normal saline treatment group; MSCs: Undifferentiated Wharton’s jelly mesenchymal stem cells treatment group; IPCs: Insulin-producing cells treatment group.

Figure 5 Comparison of pancreatic immunofluorescence staining in the different treatment groups of diabetic rats. A: Pancreas of rats from the saline treatment group (20 ×); B: Pancreas of rats from the mesenchymal stem cell treatment group (10 ×); C: Pancreas of rats from the insulin-producing cell treatment group (10 ×). Red: Human cell nucleus; green: human insulin.

Figure 6 Comparison of pancreatic immunohistochemistry staining in the different treatment groups of diabetic rats. A, B: Pancreas of rats from the normal saline (NS) treatment group (40 ×); C, D: Pancreas of rats from the mesenchymal stem cell (MSC) treatment group (40 ×); E, F: Pancreas of rats from the insulin-producing cell (IPC) treatment group (40 ×); G: Intact islets: 0% lymphocyte infiltration, peri-insulitis: < 25% lymphocyte infiltration, intra-insulitis: 25%-50% lymphocyte infiltration, severe insulitis: > 50% lymphocyte infiltration. The percentage of islets free from lymphocyte infiltration was about 7% in rats from the NS treatment group but was 38% in rats from the MSC treatment group (^aP < 0.05). Only 18% of the islets from MSC-treated rats showed severe insulitis compared with 43% of rats from the NS treatment group (^aP < 0.05). NS: normal saline treatment group; MSCs: Undifferentiated Wharton’s jelly-MSCs treatment group; IPCs: Insulin-producing cells treatment group; Red: Human cell nucleus; Brown: Human insulin.