Abstract

Successful islet isolation is the key to successful islet transplantation. Our group recently modified the islet isolation protocol to include pancreatic ductal injection of the preservation solution, pancreas storage in modified extracellular-type trehalose-containing Kyoto (MK) solution, and use of an iodixanol-based purification solution and bottle purification. In this study, we applied these methods to porcine islet isolation after 18-h pancreas preservation and compared two solutions with different compositions in bottle purification. Islet yield before purification was 651,661 ± 157,719 islet equivalents (IE) and 5576 ± 1538 IE/g pancreas weight. An IU solution was made by adding iodixanol to University of Wisconsin solution and an IK solution was made by adding iodixanol to MK solution. The efficacy of the two solutions for islet isolation was compared. There were no significant differences between the two purification methods with regard to islet yield, survival rate, purity, score, or stimulation index. These results indicate that our isolation protocol produces efficient islet yields from prolonged cold-stored pancreas and that IU and IK solutions are equally useful for islet purification.

Highlights

  • Pancreatic islet transplantation is an excellent potential treatment for type 1 diabetic patients with difficulty controlling blood glucose levels or hypoglycemia unawareness despite maximal care [1,2,3,4,5]

  • We previously reported that a controlled density gradient with iodixanol and organ preservation solution during islet purification leads to a better recovery rate than that with Ficoll solution in human islet isolation [6]

  • We previously showed that modified extracellular-type trehalose-containing Kyoto (ETK) solution significantly improved the islet yield compared to University of Wisconsin (UW) preservation for both 2- and 18-h preservation [8,9]

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Summary

Introduction

Pancreatic islet transplantation is an excellent potential treatment for type 1 diabetic patients with difficulty controlling blood glucose levels or hypoglycemia unawareness despite maximal care [1,2,3,4,5]. Ficoll solution is the most commonly used solution for purification of pancreatic islets [1,2]. We previously reported that a controlled density gradient with iodixanol and organ preservation solution during islet purification leads to a better recovery rate than that with Ficoll solution in human islet isolation [6]. We previously showed that modified extracellular-type trehalose-containing Kyoto (ETK) solution significantly improved the islet yield compared to UW preservation for both 2- and 18-h preservation [8,9]. Modified ETK (MK) solution contains ulinastatin, a trypsin inhibitor, and has a high sodium/low potassium composition. Because the trypsin activity during pancreas preservation affects autolysis and the high potassium concentration induces insulin release from islets [10], MK solution is advantageous for the storage of pancreata for islet transplantation. Given that the use of human pancreatic tissue from cadaveric donors for research is against the law in Japan, we used porcine pancreatic tissue in this study

Pancreatic Islet Isolation
In Vivo Assessment
Characteristics of the Isolated Porcine Islets
Conclusions
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