Vascularized Islet Transplantation as Composite Islet-Kidney Grafts with Nanoparticle-Labeled Islets in Large Animal Preclinical Transplant Models.

Although there are many patients with diabetes and end-stage renal failure (DM/ESRD) who would benefit from a transplantation strategy that addresses both their ESRD and its underlying cause, current methods of islet and kidney transplantation using live donors have had only limited success. The first major obstacle is that the number of islets obtained from a live donor partial pancreatectomy is generally insufficient to cure diabetes in recipients, as large numbers of intraportally administered islets are lost due to ischemia before they are engrafted and vascularized in the recipient liver. To overcome this hurdle, we have developed a strategy to transplant islets as a vascularized graft. Autologous prevascularization of donor islets under the donor's own renal capsule prior to transplantation preserves islets and thus achieves normal glycemic control in diabetic recipients in our preclinical transplant models with a limited donor pancreas resection. In addition, from an immunological perspective, the innate tolerogenic qualities of the kidney provide immunoprotection for the engrafted, vascularized islets when they are transplanted as part of the composite islet-kidney (I-K) grafts. This "Trojan Horse" approach of transplanting a composite I-K eliminates the lengthy time which is otherwise required for vascularization of intraportally administered free islets, minimizing loss of islets to ischemic damage and facilitating the induction of tolerance. We have also recently developed a strategy to further minimize the required size of resected donor pancreas to prepare composite I-K graft using a novel, synthesized, small interfering RNA (siRNA)-nanoparticle probe. In this chapter, we introduce our living donor transplantation strategy to cure diabetic nephropathy using composite I-K graft.