Zona pellucida removal modifies the expression and release of specific microRNAs in domestic cat blastocysts.

The culture of domestic cat embryos without the zona pellucida affects their implantation capacity. MicroRNAs (miRNAs) have an important role in embryo-maternal communication and implantation. The objective of this study was to evaluate the expression of specific miRNAs in domestic cat blastocysts cultured without the zona pellucida. Two experimental groups were done: (1) domestic cat embryos cultured with the zona pellucida (zona intact control group, ZI); and (2) cultured without the zona pellucida (zona free group, ZF). The cleavage, morula and blastocyst rates were evaluated. The blastocysts and their spent medium were used for miRNA expression analysis using RT-qPCR ( and ). The pre-mature microRNAs (pre-miRNAs) and miRNAs were evaluated in the blastocysts and only miRNAs were evaluated in the spent medium. No differences were observed in the cleavage, morula and blastocyst rates between the ZF and ZI groups ( > 0.05). For miRNAs analysis, and had the most stable expression and were selected as internal controls. ZF blastocysts had a higher expression of , , and and a lower expression of than their ZI counterparts ( < 0.05). Furthermore, higher levels of , and were detected in the spent medium of ZF blastocysts ( < 0.05). In conclusion, culture of domestic cat embryos without the zona pellucida modifies the expression of , , , and at the blastocyst stage and the release of , and .