Encapsulated Pancreatic Cell Islet Products

Joslin Diabetes Center, Inc.
posted on 03/09/2009

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The efficacy of islet cell transplantation as a therapeutic strategy for diabetes has been demonstrated in humans by the Edmonton Protocol, but a number of obstacles remain for wide scale application. Problems encountered to date include the need for patients to permanently take immunosuppressive drugs, which may entail serious side effects. Microencapsulation has been used for full or partial protection of transplanted islets from immune rejection, however, the use of microcapsules in general prevents islet revascularization and serves as a barrier to optimal oxygen transport to the islets. Reduced oxygen transfer can lead to a hypoxic core within the islet that results in tissue death and reduced function. The present invention solves this problem by providing a preparation with enhanced islet survival and function without unduly limiting oxygen transport to the cells. The invention features aggregated pancreatic islet cells encapsulated in a biocompatible matrix, into which a material has been dispersed which aids in oxygen transport to the cells. This material is known to have favorable oxygen transport properties, but has not previously been used or investigated for islet transplantation. Islets encapsulated in such a matrix were viable in low oxygen concentrations, and were capable of reversing the diabetic phenotype when implanted in an animal model of the disease. The invention offers considerable advantages over other methods of islet encapsulation, in allowing human or animal islets to be maintained within the body at high levels of viability without immune rejection.