X-Message-Number: 11520
Date: Tue, 6 Apr 1999 12:11:35 -0700 (PDT)
From: Doug Skrecky <>
Subject: formaldehyde in cryoprotectant

Authors
  Mahadevan MM.  McIntosh Q.  Miller MM.  Breckinridge SM.  Maris M.  Moutos
  DM.
Institution
  University of Arkansas for Medical Sciences, Department of Obstetrics and
  Gynecology, Little Rock, USA.
Title
  Formaldehyde in cryoprotectant propanediol
  and effect on mouse zygotes.
Source
  Human Reproduction.  13(4):979-82, 1998 Apr.
Abstract
  Cryopreservation of human zygotes and embryos has been routinely performed by
  in-vitro fertilization clinics for many years. Karran and Legge (1996) first
  reported that formaldehyde (FA) present in the
  cryoprotective solutions can have a deleterious effect on mouse oocytes. FA
  is a cytotoxic, carcinogenic and mutagenic chemical. The effect of FA on
  mouse zygotes was investigated. In addition, the concentrations of FA in
  propanediol (PROH) obtained from various sources were determined. Pooled
  1-cell embryos were dispensed into droplets of modified Ham's F10 or human
  tubal fluid containing various concentrations of FA. Since bovine serum
  albumin (BSA) may minimize toxicity additional trials were done as above in
  the absence of BSA. FA concentration in the standard 1.5 M PROH, from
  different sources in water, was measured in the same assay using a standard
  curve of 0-100 microM FA. FA in a complex medium had a significant
  deleterious effect on embryo development and hatching but only at 1 mM
  concentration (P < 0.000001; see Tables I-III). There was no significant
  effect of FA at 100 microM. However, in a simple medium even 50 microM FA
  decreased embryo hatching. FA was present in 1.5 M PROH from different
  sources (range 1.0-35.3 microM concentration). It appears that FA
  concentrations do not increase with storage because FA concentrations were
  low even after opening and storage for 3 years on the shelf. This suggests
  that FA is a contaminant during the manufacturing process and may vary from
  manufacturer to manufacturer and batch to batch. Until further studies are
  done to confirm the lack of toxicity to embryos during cryopreservation (with
  or without FA scavengers) it may be prudent to screen all batches of
  cryoprotectants for FA as part of quality control.

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