Comparisons of Differentiation Potential in Human Mesenchymal Stem Cells from Wharton's Jelly, Bone Marrow, and Pancreatic Tissues

Abstract

Background. Type 1 diabetes mellitus results from autoimmune destruction of β-cells. Insulin-producing cells (IPCs) differentiated from mesenchymal stem cells (MSCs) in human tissues decrease blood glucose levels and improve survival in diabetic rats. We compared the differential ability and the curative effect of IPCs from three types of human tissue to determine the ideal source of cell therapy for diabetes. Methods. We induced MSCs from Wharton's jelly (WJ), bone marrow (BM), and surgically resected pancreatic tissue to differentiate into IPCs. The in vitro differential function of these IPCs was compared by insulin-to-DNA ratios and C-peptide levels after glucose challenge. In vivo curative effects of IPCs transplanted into diabetic rats were monitored by weekly blood glucose measurement. Results. WJ-MSCs showed better proliferation and differentiation potential than pancreatic MSCs and BM-MSCs. In vivo, WJ-IPCs significantly reduced blood glucose levels at first week after transplantation and maintained significant decrease till week 8. BM-IPCs reduced blood glucose levels at first week but gradually increased since week 3. In resected pancreas-IPCs group, blood glucose levels were significantly reduced till two weeks after transplantation and gradually increased since week 4. Conclusion. WJ-MSCs are the most promising stem cell source for β-cell regeneration in diabetes treatment.

Figure 1

Real-time PCR analyses of three kinds of cell sources after differentiation to evaluate the expression of pancreatic β-cell development-related and insulin production-related genes, including Pdx1, Pax4, Glut2, and Insulin. Results are the means ± SD for 6 experiments. ^∗:P < 0.05 compared to nondifferentiated cells.

Figure 2

Insulin-to-DNA ratio in three different types of human tissue MSCs. Insulin-producing cells cultured in the maturation phase were stimulated as indicated and C-peptide in the medium was analyzed using ELISA. Measurements were normalized for DNA content of each sample. Three samples per condition were measured. Similar results were obtained in at least three independent experiments.

Figure 3

Secretion of C-peptide by cultured human IPCs in response to glucose stimulation. Glucose challenge test for C-peptide release in response to low glucose (LG: 5.5 mM) and high glucose (HG: 25 mM) concentrations of differentiated cells. (⁺: the increasing fold of resected pancreas compared to the increasing fold of Wharton's jelly, P < 0.05; ^#: the increasing fold of resected pancreas compared to the increasing fold of bone marrow, P < 0.05; ^∗: the increasing fold of bone marrow compared to the increasing fold of Wharton's jelly).

Figure 4

Changes in blood glucose levels in STZ-induced diabetic rats (study group: transplantation of IPCs into the portal vein via the Port-A-Cath with Wharton's jelly MSCs, BM-MSCs, and resected pancreas; STZ group: STZ-induced diabetic rats without transplantation of insulin-producing cells) Results are presented as the mean ± SD for 6 rats. ^∗:P < 0.05 BM-IPCs group compared to WJ-IPCs group; ^#: P < 0.05 resected pancreas-IPCs compared to WJ-IPCs group.

Figure 5

WJ-MSCs differentiated into IPCs and resided in the pancreas of the STZ rat. Confocal analysis of the pancreas tissues 23 days after WJ-IPCs transplantation showed clusters of cells with GFP expression and human C-peptide expression (red) as well as the nuclear stain, DAPI (blue). Scale bar = 50 μm.