Estimation of donor usability for islet transplantation in the United States with the kyoto islet isolation method.

The quality of donor pancreata is important for successful islet isolation. However, in some countries like Japan, the number of donor pancreata is very low; therefore, marginal donors have been used with less restrictive donor criteria. In order to use marginal donor pancreata, we established the Kyoto islet isolation method (KIIM). According to United Network for Organ Sharing (UNOS) in 2005, more than 6,000 pancreata were not clinically used in the US. In this study, we applied the KIIM for brain-dead donors and reevaluated donor usability based on the Japanese islet donor criteria. Islets were isolated with the Ricordi method using pancreata stored in University of Wisconsin (UW) solution (UW group) or by the two-layer method (TLM group) or the TLM combined with ductal injection (DI group). We implemented the KIIM (KIIM group) to confirm the effect of the KIIM on brain-dead donors. Donor charts in Texas from 2005 to 2006 were reviewed. If pancreata were not used clinically, the reason was reviewed and donors were reevaluated based on Japanese criteria. There were no significant differences of islet yield, viability, and purity between the UW and TLM groups. The DI group significantly improved islet yields and isolations were further improved in the KIIM group [UW: 251,663 +/- 60,217 islet equivalent (IE); TLM: 243,738 +/- 54,170 IE; DI: 498,639 +/- 28,853 IE; KIIM: 678,286 +/- 55,853]. The KIIM provided high-quality islets in high numbers from islet isolations from brain-dead donors. A total of 236 donor charts were reviewed and 194 pancreata (82%) were not used. Of these, 185 cases identified the reasons that the pancreata were not used. When we applied the Japanese criteria, an additional 82 cases out of 185 (44%) seem to be suitable for islet isolations. With the KIIM, more than 2,500 additional donor pancreata can be used for islet isolation in the US every year when the Japanese criteria are applied.