Allogeneic diabetic mesenchymal stem cells transplantation in streptozotocin-induced diabetic rat

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stroma cells which can provide a potential therapy for diabetes mellitus. But the mechanism is still controversial. Also, the status of BM-MSCs under hyperglycemia is not known. In the present study, we investigated the status of BM-MSCs in experimental-diabetic rat and demonstrated the rescue of experimental diabetes by diabetic MSCs transplantation.

BM-MSCs were cultured and the potential of multiple-differentiation was identified through induction into osteoblasts. MSCs of passage 3 were used for the following experiment. The MSCs were labeled with 5-bromo-2?-deoxyuridine (BrdU). Diabetes in rats was induced by STZ injection. The rats were divided into three groups: normal control group (no DM, rats treated with saline through tail vein, n=10); DM control group (DM, no transplantation of MSCs, n=20); experimental group (DM and transplantation of MSCs, n=20). Body weight and blood glucose of the rats were monitored during the experiment after transplantation of MSCs. Paraffin sections of pancreas were obtained from rats of each group. Immuno-histochemistry analysis and double immunofluorescence were used to detect the BM-MSCs in the pancreatic tissue and their differentiating state.

MSCs were 89.5% labeled by BrdU and DAPI, which was green/blue double stained under fluorescent microscopy. Transplantation of diabetic MSCs resulted in a reduction of hyperglycemia on day 45 in experimental diabetic rats compared with control rats (17.7 mM +/-3.9 vs 27.8 mM +/- 2.1, P < 0.05), There was also a difference between MSC-treated experimental diabetic rats and control rats in body weight (232.7 g +/-19.7 vs 133.3g +/-13.1, P < 0.05). Histological and morphometric analysis of the pancreas of experimental diabetic rats showed the presence and differentiation of transplanted MSCs into insulin-producing cells which evidenced by double-staining of anti-BrdU and insulin. Also, there were many small islets throughout the sections. Their mean area and diameter analysis revealed that they were smaller than control islets (1835.7 +/- 175.8 microm2 vs 13257.2 +/- 1457.6 microm2; 43.5 +/- 3.7 microm vs 119.9 +/- 5.8 microm, respectively, P < 0.05).

Allogeneic MSCs transplantation can reduce blood glucose level in recipient rats. A relatively small quantity of transplanted diabetic MSCs survive and transdifferentiate into insulin-producing cells in the pancreas of recipient rats. Upon transplantation these cells initiate endogenous pancreatic regeneration by neogenesis of islet of recipient origin. The present study demonstrates that diabetic MSCs retains its stemness and potential to induce pancreatic regeneration on transplantation.