Development of embryos after round spermated injection in the outbred mouse

Abstract

Although round spermatid injection (ROSI) can be used as a progressive assisted reproductive Technology (ART) for treatment of male infertility, however the successful rate of embryos and full-term development after ROSI is still significantly lower than that for intracytoplasmic sperm injection (ICSI). In this study, we succeed in improving the potential of ROSI oocytes developed to the blastocyst stage and the quality of embryos by treatment of ROSI oocytes with histone deacetylase inhibitor (HDACi) scriptaid for 6 hours after injection. Our results found that ROSI oocytes treated with scriptaid prolong duration of histone H3K9 demethylation in round spermatid origin DNA until the 2-cell stage embryos. In contrast, high rate of ROSI embryos with high histone methylated at H3K9 in round spermatid origin DNA was observed at the 2-cell stage embryos in group of ROSI oocytes without scriptaid treatment. Interestingly, our study also found that ROSI oocytes treated with scriptaid for 6 hours after injection enhanced newly synthesized mRNA levels at the 2-cells stage embryos. In conclusion, this study demonstrated that treatment of ROSI oocytes with scriptaid for 6 hours after injection improved histone H3K9 modifications, transcriptional activity at the 2-cell stage embryos, and finally could enhance the successful rate of ROSI embryo development to the morula and blastocyst stage. Moreover, the quality of blastocyst in case of ROSI with scriptaid treatment was clearly improved due to the increasing of the number of inner cell mass (ICM) cells and the total cells in ROSI expanded blastocyst stage when compared to the blastocyst of ROSI without scriptaid treatment. Keywords: Round spermatid injection (ROSI), histone H3K9 methylation, histone deacetylase inhibitor scriptaid, nascent mRNA, in vitro development of mouse embryos