Aberrant epigenetic modification in murine brain tissues of offspring from preimplantation genetic diagnosis blastomere biopsies

Abstract

Preimplantation genetic diagnosis (PGD) has been prevalent in the field of assisted reproductive technology, yet the long-term risks of PGD to offspring remain unknown. In the present study, the early development of PGD embryos, postimplantation characteristics, and birth rate following PGD were determined. Moreover, the behavior of the offspring conceived from the biopsied embryos was evaluated with the Morris water maze and pole climbing tests. Finally, the epigenetic modification of the global genome and methylation patterns for the H19, Igf2, and Snrpn imprinted genes were identified. The results indicated a significant delay in the blastocoel formation of PGD embryos and a decrease in the implantation ability of these embryos, which was related to the decreased number of cells in the PGD blastocysts. The PGD mice spent more time on both the nontrained quadrant of the water maze and climbing down the pole. Furthermore, the 5-hydroxymethylcytosine content in the brain tissues of PGD mice was significantly increased, but no difference was found in 5-methylcytosine content. The differentially methylated regions of H19/Igf2 exhibited decreased methylation patterns, but that of Snrpn was normal, compared to the control group. Quantitative RT-PCR indicated that Igf2 mRNA expression was significantly decreased but that H19 and Snrpn mRNAs were expressed normally. In conclusion, blastomere biopsies in PGD procedures carry potential risks to embryo development and the behavior of resulting offspring; these risks may arise from aberrant epigenetic modification and methylation patterns in brain tissues. Further studies are needed to better understand the risks associated with PGD.

Keywords: assisted reproductive technology; behavior; blastocoel formation; blastomere biopsy; compaction; developmental biology; epigenetics; guinea pigs; methylation; mice; preimplantation genetic diagnosis; rodents (rats; voles).