Islet Cell Transplantation: In Vivo and in Vitro Functional Assessment of Nonhuman Primate Pancreatic Islets

Abstract

Transplantation of pancreatic islets of Langerhans as a therapeutic approach for treatment of type I diabetes offers an alternative to subcutaneous insulin injections. Normalization of blood glucose levels by transplanted islets may prevent the development of diabetes-related complications. Problems related to rejection, recurrence of autoimmunity, and local inflammation upon transplantation of islets into the liver need to be solved before the implementation of islet cell transplantation can be viewed as a justifiable procedure in a large cohort of patients. Islet cell isolation has been quite successful in small animals, but the translation of this approach to nonhuman primates has been less rewarding. One of the main problems encountered in nonhuman primate models is the difficulty of isolating an adequate number of functional islets for transplantation. The aim of the present study was to develop a method for isolating a sufficient number of viable islets from nonhuman primates to allow for reversal of diabetes. By implementing minor modifications in the automated method for human islet isolation we were able to obtain viable, functional islets that responded normally to glucose stimulation in vitro. These islets were also able to reverse diabetes in immunocompromised nude mice, rendered diabetic by streptozotocin. This method of islet cell isolation has enabled us to proceed with protocols of allogeneic islet cell transplantation in preclinical, nonhuman primate models.

A Novel Method for the Assessment of Cellular Composition and Beta-Cell Viability in Human Islet Preparations

“…Mice with sustained hyperglycemia (>300 mg/dL) were used as islet graft recipients. 2000 human IEQ per recipient were transplanted under the kidney capsule (11,21,22) and nonfasting blood glucose values were assessed three times a week. Reversal of diabetes was defined as stable nonfasting blood glucose <200mg/dL.…”

Development of a Chimeric Anti-CD40 Monoclonal Antibody That Synergizes with LEA29Y to Prolong Islet Allograft Survival

“…Rhesus monkey islet isolation was completed via minor modifications of the automated method for human islet isolation (21,22) using Liberase (Roche) at a concentration of 0.47-0.71 mg/ml. A three-layer, discontinuous Euroficoll gradient (densities 1.108, 1.097, and 1.037; Mediatech) and a Cobe 2991 blood cell processor (Gambro) were used for purification of islets from the pancreatic digest.…”

Pancreatic Islet Transplantation Using the Nonhuman Primate (Rhesus) Model Predicts That the Portal Vein Is Superior to the Celiac Artery as the Islet Infusion Site

“…Nonhuman primates are highly relevant because of their phylogenetic relationship to humans (6) and because many of the newer immunomodulatory agents (antibodies and receptor fusion proteins) are specific for human epitopes, many of which cross-react with the corresponding primate epitopes. (5,7,8).We sought to establish a nonhuman primate model to closely mimic a recently reported steroid-sparing regimen (5,9). Currently, isolated islets are transplanted in the clinical setting via a catheter percutaneously placed into the recipient's portal vein to the liver (5).…”

“…Nonhuman primates are highly relevant because of their phylogenetic relationship to humans (6) and because many of the newer immunomodulatory agents (antibodies and receptor fusion proteins) are specific for human epitopes, many of which cross-react with the corresponding primate epitopes. (5,7,8).…”