Treatment of streptozotocin-induced diabetes mellitus by transplantation of islet cells plus bone marrow cells via portal vein in rats

Background. We have established a new method for the transplantation of allogeneic pancreatic islets (PIs) using sublethal irradiation (9 Gy) plus simultaneous transplantation of PIs and bone marrow cells (BMCs) via the portal vein (PV) followed by intravenous (i.v.) injection of donor BMCs (9 Gy + PV + i.v.). Methods. Approximately 600 PIs of Brown Norway (BN: RTIA(n), RTlBn) rats were transplanted into the liver of streptozotocin-induced diabetic Fischer 344 (F344: RT1A(n), RT1B(n)) rats via the PV. BMCs (3x10(8)) of BN rats were injected via the PV or i.v. into the recipients simultaneously. In some groups, additional i.v. injections of BMCs from BN rats were given 5 days after the PI transplantation. Results. All the recipients (10 of 10) in the 9 Gy + PV + i.v. group showed normoglycemia for more than 1 year, whereas PIs were rejected within 30 days after transplantation in the group of 9 Gy + i.v. + i.v. Conclusions. These results suggest that simultaneous transplantation of PIs and BMCs via the PV is effective in inducing persistent tolerance.