Comparative Study on Biologic and Immunologic Characteristics of the Pancreas Islet Cell Between 24°C and 37°C Culture in the Rat

The aim of this study was to investigate the effect of culture at 24°C on cell viability, cellular function, immunogenicity, and cytokine profiles of rat pancreatic islets. Pancreatic islets were isolated from Lewis rats and cultured at either 24°C or 37°C for 14 days. Islet recovery was counted as islet equivalents; islet viability was examined with fluorescent vital staining. Islet function was measured with a glucose stimulation test. Annexin V, and MHC class I and II expression were measured using flow cytometric assay for apoptosis and immunogenicity, respectively. Lymphocyte cell proliferation was examined with WST-1 proliferation assay. Cytokine profiles were analyzed with quantitative real time RT-PCR. All these parameters were measured on 1, 3, 5, 7 and 14 culture days after islet isolation. Islet recovery was higher in islets cultured at 24°C than 37°C without a change in viability. Insulin secretion after glucose stimulation was more effective in 24°C culture conditions. Decreased apoptotic cell death was demonstrated in 24°C cultured islets. Both MHC class I and II expression on islets and lymphocyte proliferation upon coculture with islets were less prominent in 24°C cultured islets. TNF-α expression was lower in islets cultured at 24°C than in islets cultured at 37°C. Both IL-1β and IL-10 cytokine expressions were similar under both culture conditions. This study demonstrated that cell recovery and function are increased in islets cultured at 24°C than those at 37°C with decreased antigenicity and proinflammatory cytokine expression.