The Effect of Step-wised, Controlled Cooling Method for Islet Cryopreservation on the in vivo and in vitro Islet Function

Jeong, In Kyung; Oh, Seung Hoon; Kim, Byung Joon; Yang, Tae Young; Lee, Byung Wan; Ha, Chang Young; Noh, Jung Hyung; Chung, Jae Hoon; Min, Young Ki; Lee, Myung Shik; Lee, Moon Kyu; Kim, Kwang Won

Abstract

BACKGROUND: Although islet transplantation has been attempted to reverse the state of diabetes, achieving a critical number of islets and modulating the immune response limit the success ofl islet transplantation. Cryo-preservation of islets offers many important benefits for islet transplantation by collecting islets with a wide variety of HLA phenotypes and islet MHC expression. The aims of this study was to determine the optimal conditions for cryo-preservation by using a controlled cooling method and to evaluate in vitro and in vivo functional properties of the cryo-preserved islets.
METHODS
Collagenase-isolated, Ficoll-purified islets were cultured for 48 hours. They were aliquoted into freezing tubes (1000 islets per tube), equilibrated with 2 M dimethyl sulfoxide (DMSO) in three steps, supercooled, nucleated, and controll- cooled at rate of 0.25 degrees C/min to - 40 degrees C prior to storage at - 196 degrees C. Rapid thawing and removal of DMSO with 0.75 M sucrose preceded 48 hour of culture and the morphology, viability, glucose-induced insulin secretion, and in vivo function of rats transplanted with cryopreserved islets was reexamined.
RESULTS
1) Recovery was 90.2+/-0.2%, 85.7+/-0.1% and 81.7+/-0.1% immediately after, 24 hours and 72 hours after thawing respectively. The viability was 60+/-5%, 80+/-5%, 90+/-5% immediately after, 24 hours and 72 hours after thawing respectively. 2) The glucose-stimulated-insulin secretion (GSIS) tended to decrease immediately after thawing, but GSIS increased to the level of pre-cryopreservation 72 hours after thawing. 3) The in dynamic GSIS, the first and the second phase of insulin secretion were well preserved in islets cultured for 72 hours after thawing. 4) The cryopreserved islets were cultured for 3 days and transplanted into renal sub-capsular space of streptozotocin (STZ) induced diabetic rats. The duration of normoglycemia in the STZ-induced diabetic rats transplanted with cryopreserved islets was significantly longer than that of the fresh islets.
CONCLUSION
The optimal condition of cryopreservation using the controlled cooling method was established in rat pancreatic islets. This cryopreservation method can be a feasible approach for human islet transplantation.