Chromosomal abnormality rate in human pre-embryos derived from in vitro fertilization cycles cultured in the presence of Follicular-Fluid Meiosis Activating Sterol (FF-MAS).

BACKGROUND The objective of the study was to investigate the effect of Follicular-Fluid Meiosis Activating Sterol (FF-MAS) when added to the culture media on the incidence of chromosomal abnormalities and pre-embryo development in human pre-embryos. METHODS 243 women undergoing IVF/ICSI treatment donated 353 oocytes in a multicentre, prospective, randomized, double blind, four-arm, controlled trial performed at Danish and Swedish public and private IVF centers. Metaphase II oocytes were randomly assigned to: FF-MAS 5 microM, FF-MAS 20 microM, ethanol 0.2% (vehicle control) or water for injection (inert control). The exposure regimen of FF-MAS to the human oocytes was 4 h prior to fertilization by ICSI and 20 h exposure post ICSI. The primary endpoint was the incidence of numerical chromosomal abnormalities. Secondary endpoints were cleavage rate and pre-embryo quality. RESULT On the pre-embryo level, no significant differences in chromosomal abnormality rate were observed among the four groups. However, the percentage of uniformly normal pre-embryos was significantly lower in the pooled FF-MAS group (5 microM: 12% and 20 microM: 17%) than in the pooled control group (inert control 32% and vehicle control 42%). A high level of mosaicism (41-60%) was found in all groups. At the blastomere level, the percentage of blastomeres categorized as normal was significantly lower in the FF-MAS 5 microM group (41%) and the FF-MAS 20 microM (29%) group versus the inert (52%) and the vehicle (61%) groups. Significantly reduced cleavage and good quality pre-embryo rates were found in both FF-MAS groups. CONCLUSION FF-MAS increased the rate of aneuploidy and had detrimental effects on cleavage and pre-embryo development, when exposed both before and after fertilization.