Antioxidant supplementation of culture medium during embryo development and/or after vitrification-warming; which is the most important?
OBJECTIVE
To determine the most optimal stage for antioxidant supplementation of culture medium to improve developmental competence, cryotolerance and DNA-fragmentation of bovine embryos.


METHODS
Presumptive zygotes were first cultured in presence or absence of beta-mercaptoethanol (beta-ME), for 8 days. Subsequently, half of the expanded blastocysts developed in both groups were vitrified, warmed within 30 min and post-warming embryos along with their corresponding non-vitrified embryos were cultured for two further days in presence or absence of (100 microM) betaME.


RESULTS
For vitrified and non-vitrified embryos, the best effect was found when betaME was added from day 1 of in vitro culture in continuation with post-warming culture period. Day 1-8 supplementation significantly increased the rates of cleavage, day 7 and day 8 blastocyst production. For non-vitrified embryos, betaME addition during day 1-8 and/or 9-10 of embryo culture improved both hatching rate and quality of hatched embryos. For vitrified embryos, however, the percentage of DNA-fragmentation (18.5%) was significantly higher (p < or = 0.05) than that of embryos developed in absence of betaME but supplemented with betaME during post-warming period (13.5%).


CONCLUSIONS
Exogenous antioxidant increases the chance of embryos, even those of fair-quality, to develop to blastocyst. However, antioxidant inclusion during in vitro embryo development is not sufficient to maintain the redox state of these embryos during the critical period of post-warming embryo culture, and therefore, there should be a surplus source of exogenous antioxidant during post-warming embryo culture.
Hosseini
S M
SM
Department of Clinical and Experimental Embryology, Cell Sciences Research Centre, Royan Institute, ACECR, Tehran, Iran.
Forouzanfar
M
M
Hajian
M
M
Asgari
V
V
Abedi
P
P
Hosseini
L
L
Ostadhosseini
S
S
Moulavi
F
F
Safahani Langrroodi
M
M
Sadeghi
H
H
Bahramian
H
H
Eghbalsaied
Sh
Sh
Nasr-Esfahani
Mohammad H
MH
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001755:Blastocyst / Q000187:drug effects*; D002417:Cattle; D015925:Cryopreservation / Q000379:methods*; D003470:Culture Media; D046149:Embryo Culture Techniques; D004624:Embryo Transfer; D005260:Female; D005615:Freezing; D008623:Mercaptoethanol / Q000494:pharmacology*
D000975:Antioxidants; D003470:Culture Media; D008623:Mercaptoethanol