Combinatorial Treatment of Bone Marrow Transplantation and Regulatory T Cells Improves Glycemia in Streptozotocin-diabetic Mice.

Autologous hematopoietic stem cell transplantation (HSCT) has limited benefits in patients with a long-duration of diabetes. To test whether a T regulatory cells (Tregs) and syngeneic bone marrow transplantation (syn-BMT) co-transplantation regimen will be effective, BMT±Tregs infusion was performed in streptozotocin-diabetic mice with a long-duaration of diabetes. Diabetic status, pancreata morphometry and Tregs/Th17 balancing were tested on day 100 after transplantation. While hyperglycemia relapsed in mice receiving BMT monotherapy about 6 weeks after transplantation, combined therapy with BMT+Tregs improved hyperglycemia and C-peptides, preserved islet cell mass within 100 days after BMT. Although both groups BMT and BMT+Tregs induced Tregs/Th17 rebalancing, combined treatment of BMT+Tregs synergistically elevated TGF-β1 and FoxP3 expression compared with BMT monotherapy. The sustained rebalance of Tregs/Th17 may be one possible explanation for the longer benefits of the combined treatment of BMT+Tregs over BMT monotherapy to mice with a long-duaration of diabetes. This observation of the therapeutic potential of BMCs+Tregs treatment may have important implications for clinical therapy for patients with a long-duration of diabetes.