X-Message-Number: 11596
Date: Thu, 22 Apr 1999 02:55:23 -0700 (PDT)
From: Doug Skrecky <>
Subject: cryoprotectant permeation

Authors
  Newton H.  Fisher J.  Arnold JR.  Pegg DE.  Faddy MJ.  Gosden RG.
Institution
  Centre for Reproduction, Growth and Development, School of Clinical Medicine,
  University of Leeds, Leeds General Infirmary, UK.
Title
  Permeation of human ovarian tissue with cryoprotective
  agents in preparation for cryopreservation.
Source
  Human Reproduction.  13(2):376-80, 1998 Feb.
Abstract
  The recent improvements in the treatment of cancer by chemo- and radiotherapy
  have led to a significant increase in the survival rates of patients with
  malignant disease, but at the expense of distressing side effects. One major
  problem, especially for younger patients, is that aggressive therapy destroys
  a significant proportion of the follicular population, which can result in
  either temporary or permanent infertility. Freeze-banking pieces of ovarian
  cortex prior to treatment is one strategy for preserving fecundity. When the
  patient is in remission, fertility could, theoretically, be restored by
  autografting the thawed tissue at the orthotopic site or by growing isolated
  follicles to maturity in vitro. Recent studies have found good follicular
  survival in frozen-thawed human ovarian tissue but to optimize the process an
  effective cryopreservation method needs to be developed. An essential part of
  such a technique is to permeate the tissue with a cryoprotectant to minimize
  ice formation and the extent of this equilibration is an important
  determinant of post-thaw cellular survival. In the current study, we have
  investigated the diffusion of four cryoprotective
  agents into human tissue at both 4 degrees C and 37 degrees
  C. We have also studied the effect of adding different concentrations of the
  non penetrating cryoprotective agent, sucrose, to the
  freezing media using the release of lactate dehydrogenase as a measure of its
  protective effect. At 4 degrees C propylene glycol and glycerol penetrated
  the tissue significantly slower than either ethylene glycol or dimethyl
  sulphoxide. At the higher temperature of 37 degrees C all four
  cryoprotectants penetrated at a faster rate, however concern about enhanced
  toxicity prevents the use of these conditions in practice. Thus, the results
  suggest that the best method of preparing tissue for freezing is exposure for
  30 min to 1.5 M solutions of ethylene glycol or dimethyl sulphoxide at 4
  degrees C; this achieved a mean tissue concentration that was almost 80% that
  of the bathing solution. We also report that the addition of low
  concentrations of sucrose to the freezing medium does not have a significant
  protective effect against freezing injury.

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