Super-High-Dose Islet Transplantation Is Associated With High SUITO Index and Prolonged Insulin Independence: A Case Report

Abstract

Introduction One of the current issues of clinical islet transplantation is the difficulty to achieve a prolonged insulin-free status. Functional islet mass gradually decreased after transplantation. We developed the SUITO index, which reflects engrafted islet mass. The SUITO (Secretory Unit of Islet Transplant Objects) index more than 26.0 is associated with an insulin-free status. In this study, we have experienced that super-high-dose islet transplantation maintained insulin-free status and a high SUITO index for a prolonged period. Materials and methods Two islet isolations were performed in February 2007 and January 2008. Ductal injections were performed at the procurement site using the ET-Kyoto solution and pancreata preserved by a two-layer method. Islets were isolated using the modified Ricordi method. Both isolated islets were transplanted into a type 1 diabetic patient. Efficacy of islet transplantation was assessed by the amount of insulin requirements and SUITO index. Results Islet yields were 514,467 islet equivalents (IE) and 872,174 IE, with purities of 49% and 85% for the first and second islet transplantations, respectively. The patient received a total of 24,327 IE/kg body weight. The immunosuppression was based on the Edmonton protocol. After the second islet transplantation, the average SUITO index for the following 1 month was 48.5, and the patient became insulin-free. At postoperative day 1006, the SUITO index was 44.6 and the patient maintained an insulin-free status with excellent glycemic control. Conclusion Super-high-dose islet transplantation was associated with an high SUITO index and prolonged insulin independence.