Examination of Gene Expression Profile of Functional Human Pancreatic Islets After 2-Week Culture

Islet transplant faces significant challenges, mainly because of the high incidence of primary nonfunction of transplanted islets. Protocol modifications to improve the rate of islet function have included changes in pancreatic preservation and the introduction of short-term culture. Islet culture for 48 to 72 hours has become a standard part of most successful protocols for clinical islet transplantation. We have previously reported gene expression profiles associated with human pancreatic islet function. The aim of this study was to determine the change in gene expression profiles of functional islets after 2 weeks of culture in Memphis-serum free media. Human islets from four isolations were maintained in culture for 14 days in Memphis-serum free media. RNA was extracted from 10000 IEQ for analysis of the gene expression profiles using high-density Affymetrix U133A GeneChips and Genespring software. Islet function was assessed by measurements of human C-peptide at days 7 and 14 posttransplant into NOD-SCID mice. Human C-peptide levels were determined by radioimmunoassay. Our preliminary data showed that genes related to functionality, such as those directed toward insulin processing and secretion, did not vary over 14 days of culture, while genes related to exocrine pancreas and organ architecture and immune-associated genes decreased over time. The ability to maintain islets in culture is an important step toward the development of islet tissue repositories, as well as toward screening human islet preparations for additional pathogens.