Cold preservation of islets in UW solution--with special reference to apoptosis.

Background Apoptosis progresses in cultured islets. Little is known with regard to apoptosis under cold preservation. We examined viability and function of islets in University of Wisconsin (UW) solution. Materials and methods Isolated rat islets were cultured overnight (overnight group) and further treated with 7-day culture in RPMI 1640 medium at 37°C (culture group) or 7-day preservation in UW solution at 4°C (preservation group). They were evaluated by glucose-stimulated insulin secretion test. Apoptosis was examined by TdT-mediated dUTP-biotin nick end-labeling (TUNEL) assay. Expression of caspase mRNA and the ratio of Bax to Bcl-2 were evaluated by reverse-transcriptase polymerase chain reaction (RT-PCR). Results Islet recovery after 7 days was significantly lower in culture group than in preservation group (44.0 ± 3.7% versus 75.0 ± 4.9%, P versus 4.1 ± 0.4, P versus 10.8 ± 2.0 and 27.0 ± 4.0%, P versus 8.1 ± 0.95, P Conclusions The preservation group showed better recovery and function than the culture group. Apoptosis contributed to islet loss under culture and it was significantly suppressed under cold preservation.