Simple Evaluation of Engraftment by Secretory Unit of Islet Transplant Objects for Living Donor and Cadaveric Donor Fresh or Cultured Islet Transplantation

Abstract

Background Evaluation of engraftment is important to assess the success of islet transplantation. Recently we developed secretory unit of islet transplant objects (SUITO) index for simple evaluation of engraftment. Assuming that normal subjects aged <40 years have 100% pancreatic beta-cell function, SUITO index was calculated by the formula: 1500 × fasting C-peptide immunoreactivity [ng/dL]/(fasting blood glucose [mg/dL] − 63). In this study, we compared the efficacy of islet transplantation from cadaveric and living donors using the SUITO index. Methods We performed eight islet transplantations with non–heart-beating donors (NHBDs) into five patients. Two patients received fresh islets once, one patient received fresh islets twice, one patient received cultured islets once, and one patient received cultured islets twice plus fresh islets once. In addition, one patient received fresh islets from a living donor. We calculated the SUITO index from postoperative days 3 to 30 for each case. Results Mean SUITO index after one fresh islet transplant was 11.7 ± 1.0, after two fresh islet transplants was 28.5 ± 3.4, after one cultured islet transplant was 2.1 ± 0.4, after two cultured islet transplant was 12.1 ± 1.9, and after two cultured islet transplant plus one fresh islet transplant was 26.7 ± 1.7. The mean SUITO index after single living donor islet transplant was 40.7 ± 2.6, which was significantly higher compared with all other groups. Insulin independence was obtained when the SUITO index was >26, which might reflect that 26% beta-cell mass was required for insulin independence. Conclusion SUITO index is useful to evaluate islet engraftment and to predict the possibility of insulin independence.