X-Message-Number: 12565
Date: Thu, 14 Oct 1999 22:15:32 -0700 (PDT)
From: Doug Skrecky <>
Subject: ethylene glycol is best for islet cryopreservation

Authors
  Korbutt GS.  Rayat GR.  Ezekowitz J.  Rajotte RV.
Institution
  Surgical-Medical Research Institute and Department of Surgery, University of
  Alberta, Edmonton, Canada.
Title
  Cryopreservation of rat pancreatic islets: effect of
  ethylene glycol on islet function and
  cellular composition.
Source
  Transplantation.  64(7):1065-70, 1997 Oct 15.
Abstract
  BACKGROUND: Inasmuch as cryopreservation can facilitate
  clinical islet transplantation by providing a means of storing supplemental
  islets in order to augment marginally adequate grafts, protocols are needed
  to allow for a minimal loss in viable beta cells. By replacing the
  cryoprotectant dimethyl sulfoxide (DMSO) with ethylene
  glycol (EG), a more simplified
  cryopreservation protocol was developed, which resulted in
  improved survival and function of rat pancreatic islets. METHODS: Nonfrozen
  islets, islets cryopreserved in DMSO, and EG-cryopreserved islets were
  compared for percent recovery, cellular composition, in vitro viability, and
  metabolic function after transplantation. RESULTS: After
  cryopreservation in DMSO or EG, islet yield was similar to
  that of nonfrozen controls; however, islets cryopreserved in DMSO exhibited
  lower cellular DNA, insulin, and glucagon content, as well as an impaired
  insulin secretory capacity in vitro than the nonfrozen controls. When
  compared with controls, islets cryopreserved in DMSO contained a higher
  proportion of beta cells but a lower number of glucagon-positive cells,
  whereas cryopreservation with EG resulted in similar
  DNA/hormone contents, in vitro viability, and cellular composition.
  Transplantation of islet grafts composed of comparable numbers of beta cells
  (2.1-2.3 million) corrected diabetes in 100% (6/6; nonfrozen controls), 92%
  (10/11; DMSO), and 100% (14/14; EG) of the recipients; however, those who
  received DMSO-treated islets took longer to achieve euglycemia and remained
  glucose-intolerant. CONCLUSIONS: These results demonstrate that EG allows for
  the successful cryopreservation of rat islet beta and a
  cells with the same yield and quality as nonfrozen islets. The observation
  that alpha-cell survival was better after cryopreservation
  with EG may explain the improved functional viability of these grafts.
  Further studies are needed to assess whether this protocol provides any
  advantage for cryopreserving large numbers of human islets.

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