X-Message-Number: 14326
Date: Wed, 16 Aug 2000 07:08:18 -0700 (PDT)
From: Doug Skrecky <>
Subject: permeation of ovarian tissue with cryoprotectants

  Newton H.  Fisher J.  Arnold JR.  Pegg DE.  Faddy MJ.  Gosden RG.
  Centre for Reproduction, Growth and Development, School of Clinical Medicine,
  University of Leeds, Leeds General Infirmary, UK.
  Permeation of human
  ovarian tissue with cryoprotective agents
  in preparation for cryopreservation.
  Human Reproduction.  13(2):376-80, 1998 Feb.
  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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