Highly Angiogenic, Nonthrombogenic Bone Marrow Mononuclear Cell–Derived Spheroids in Intraportal Islet Transplantation

Highly angiogenic bone marrow mononuclear cell–derived spheroids (BM-spheroids), formed by selective proliferation of the CD31 + CD14 + CD34 + monocyte subset via three-dimensional (3D) culture, have had robust angiogenetic capacity in rodent syngeneic renal subcapsular islet transplantation. We wondered whether the efficacy of BM-spheroids could be demonstrated in clinically relevant intraportal islet transplantation models without increasing the risk of portal thrombosis. The thrombogenic potential of intraportally infused BM-spheroids was compared with that of mesenchymal stem cells (MSCs) and MSC-derived spheroids (MSC-spheroids). The angiogenic efficacy and persistence in portal sinusoids of BM-spheroids were examined in rodent syngeneic and primate allogeneic intraportal islet transplantation models. In contrast to MSCs and MSC-spheroids, intraportal infusion of BM-spheroids did not evoke portal thrombosis. BM-spheroids had robust angiogenetic capacity in both the rodent and primate intraportal islet transplantation models and improved posttransplant glycemic outcomes. MRI and intravital microscopy findings revealed the persistence of intraportally infused BM-spheroids in portal sinusoids. Intraportal cotransplantation of allogeneic islets with autologous BM-spheroids in nonhuman primates further confirmed the clinical feasibility of this approach. In conclusion, cotransplantation of BM-spheroids enhances intraportal islet transplantation outcome without portal thrombosis in mice and nonhuman primates. Generating BM-spheroids by 3D culture prevented the rapid migration and disappearance of intraportally infused therapeutic cells.