Comparison of the effect of bone marrow cells infusion through the portal vein and inferior vena cava combined with short‐term rapamycin on allogeneic islet grafts in diabetic rats

AIMS/INTRODUCTION: The study aimed to compare the impact of allogeneic bone marrow cells (BMCs) infusion through the inferior vena cava (IVC) and portal vein (PV) combined with rapamycin on allogeneic islet grafts in diabetic rats. MATERIALS AND METHODS: Recipient diabetic Wistar rats were infused with islets from Sprague–Dawley rats through the PV. PKH26‐labeled BMCs of Sprague–Dawley rats were infused to recipients through the PV or IVC, followed by administration of rapamycin for 4 days. Blood glucose level was measured to evaluate the survival time of the islets. Lymphocytes separated from blood, BMCs, thymus, liver, spleen and lymph node were analyzed by flow cytometry. The peripheral blood smear, BMCs smear and frozen sections of tissues were observed by a fluorescence microscope. RESULTS: The survival time of the islets was significantly prolonged by the BMCs infusion combined with rapamycin. The rats receiving BMCs infusion through the PV induced a significantly longer survival time of the islets, and increased mixed chimeras of allogeneic BMCs in the thymus, liver, spleen and lymph node compared with the rats receiving BMCs infusion through the IVC. The amount of the mixed chimeras on day 14 was lower than that on day 7 after islet transplantation. Furthermore, PV transplantation had significantly more mixed chimera than IVC transplantation in all analyzed organs or tissues. CONCLUSIONS: BMCs infusion combined with rapamycin prolongs the islets survival and induces mixed chimeras of BMCs. PV infusion of BMCs might be a more effective strategy than IVC infusion of BMCs.