CD99-targeted immunomagnetic negative selection: A novel strategy for high-purity pancreatic islet isolation in murine models.

Abstract

<h4>Background</h4>Islet transplantation represents a promising therapeutic approach for type 1 diabetes through restoration of endogenous insulin production. However, efficient purification of islets from surrounding exocrine tissue remains a critical challenge, as current methodologies often compromise purity, yield, or islet viability.<h4>Methods</h4>We exploited the differential expression of CD99 between murine pancreatic exocrine tissue (high expression) and islets (negligible expression) to develop a novel immunomagnetic negative selection protocol. Expression patterns were validated using immunofluorescence, immunohistochemistry, and western blot. Subsequently, streptavidin-conjugated magnetic beads coupled with biotinylated anti-CD99 antibodies were employed to selectively deplete CD99-positive exocrine cells from pancreatic digests, thereby enriching viable islets.<h4>Results</h4>This approach achieved a remarkable increase in islet purity from 10.4 ± 3.9% to 93.0 ± 1.4% (P < 0.0001). Purified islets maintained structural integrity and demonstrated robust glucose-stimulated insulin secretion in vitro, comparable to islets isolated via conventional Ficoll density gradient centrifugation (P > 0.05). In a syngeneic transplantation model, 400 islet equivalents effectively reversed streptozotocin-induced diabetes, with therapeutic efficacy equivalent to Ficoll-purified islets (P > 0.05).<h4>Conclusions</h4>Our CD99-targeted immunomagnetic negative selection offers a novel, highly specific, and effective alternative for obtaining high-quality islets, as demonstrated by their excellent functional performance both in vitro and in vivo.