Abstract: Background: Pancreatic islet isolation is critical for studying islet physiology and transplantation. Traditional protocols use collagenases, causing injury to islets. In cats, collagenase protocols fail to produce functional islets, as demonstrated by glucose-stimulated insulin secretion (GSIS). Since islet cells express GLUT-2 they may adapt to hyperosmolar glucose solutions, enabling islet isolation by selective destruction of exocrine tissue.
Objective: To compare islet yield, purity, morphology, and GSIS between four protocols for islet isolation using selective osmotic shock (SOS)
Animals: Pancreata were obtained from cats in which necropsy or pancreatectomy was performed for reasons unrelated to this study.
Methods: Pancreatic tissue was mechanically disrupted and incubated in hyperosmolar RPMI solution with either 300 mmol/L (protocol A and B) or 600 mmol/L glucose (protocol C and D) for 20 (A and C) and 40 minutes (A and D). Islets were cultured for 24-48 hours. Using light microscopy, islets were quantified and assessed for purity and morphology. GSIS was measured by incubating approximately 120 islets from each protocol for 60 minutes in low (2.8mM) and high (28mM) glucose concentrations. GSIS was calculated as [insulin] at 28mM glucose/[insulin] at 2.8mM glucose. Data are presented as median and range.
Results: Islet yield was moderate (713 islet/g, [407-2261]) and morphology excellent across protocols. Protocol C resulted in the highest GSIS stimulation index (2.2 [1.0-3.6], p = 0.05).
Conclusions: SOS resulted in isolation of functional feline islets and will allow in vitro studies. Optimization to improve purity and yield are required before use in clinical islet transplantation.
