117 EFFECT OF DIFFERENT CRYOPRESERVATION METHODS ON THE QUALITY OF IN VITRO-PRODUCED BOVINE EMBRYOSH. Stinshoff A , K. Brüning A , A. Hanstedt A , D. Müller A , S. Wilkening A and C. Wrenzycki A
A University of Veterinary Medicine Hannover, Clinic for Cattle, Hannover, Germany;
B University of Veterinary Medicine Hannover, Reproductive Medicine Unit, Hannover, Germany
Reproduction, Fertility and Development 22(1) 217-217 http://dx.doi.org/10.1071/RDv22n1Ab117
Published: 8 December 2009
In vitro production (IVP) of bovine embryos has been greatly improved over the last couple of years. However, only one-third of the total number of embryos transferred worldwide are of in vitro origin. The IVP embryos still show remarkable differences compared with their in vivo-derived counterparts (i.e. bovine embryos produced in vitro are more sensitive to cryopreservation). So far, vitrification seems to be the most promising method to cryopreserve in vitro-produced bovine embryos. The aim of this study was to determine the effect of 2 different cryopreservation methods on the quality of in vitro-produced bovine embryos at the molecular level using a sensitive RT-qPCR assay. Bovine blastocysts were produced using abattoir ovaries and a standard protocol for IVP (Wrenzycki et al. 2001). They were randomly vitrified employing PBS plus ethylene glycol and DMSO or cryopreserved using a programmable freezer and 1.5 M ethylene glycol. After thawing, embryos from both groups were cultured for 48 h. After 24 h of culture re-expansion rates were documented, and after 48 h hatching rates were documented. After hatching, blastocysts were stored at -80°C for subsequent RT-qPCR analysis. The following gene transcripts known to play important roles during preimplantation development were analyzed: HSP70, GLUT-1, GLUT-3, E-CAD, ZO-1, DNMT3a, IFNτ, DCII. Re-expansion rates were 74.7% (68/91) and 75.0% (87/116) for vitrified and conventionally cryopreserved blastocysts, and 57.1% (52/91) and 55.2% (64/116) of re-expanded embryos hatched. The relative abundances of HSP70, GLUT-1, and ZO-1 transcripts were significantly affected in both groups of cryopreservation compared with the control group (hatched blastocysts without cryopreservation). Conventional cryopreservation had a significant effect on the amount of GLUT-3, DNMT3a, and IFNτ mRNA, whereas vitrification significantly affected DCII transcripts. E-CAD mRNA expression was similar in all groups of embryos. These results suggest that not only the cryopreservation process itself but also the method used to freeze the embryos had a significant influence on the mRNA expression of developmentally important genes in hatched bovine blastocysts.
The support of the H.W. Schaumann Stiftung (Germany) and Gynemed Medizinprodukte GmbH & Co. KG (Germany) is gratefully acknowledged.