The transcriptome of human oocytes is related to age and ovarian reserve.. Homo sapiens

Although it is well established that the ovarian reserve diminishes with increasing age, and that a woman’s age is correlated to lower oocyte quality, the interplay of a diminished reserve and age on oocyte developmental competence is not clear. After maturation, oocytes are mostly transcriptionally quiescent, and developmental competence prior to embryonic genome activation (EGA) relies on maternal RNA and proteins. Age and ovarian reserve both affects oocyte developmental competence, however, their relative importance in this process are difficult to tease out, as ageing is accompanied by a decrease in ovarian reserve. Oocytes store large quantities of RNA, including several noncoding transcripts (ncRNAs) involved in early development transcription and translation modulation. Despite the central role of ncRNAs in maternal to zygote transition, no characterization of the ncRNA transcriptome in human oocytes has been reported. This study aims at identifying how the human oocyte transcriptome changes across reproductive ages and ovarian reserve levels, with the goal of identifying candidate markers of developmental competence, and to assess the independent relevance of age and ovarian reserve in the changes of the transcriptome Overall design: A total of 36 vitrified/warmed MII oocytes from 30 women undergoing oocyte donation were included in this study, processed and analyzed individually. Oocytes were divided in 4 groups, each including 9 oocytes, according to the woman´s age and antral follicular count (AFC) (mean ± SD): Young with High AFC (YH; age 21 ± 1 years and 24 ± 3 follicles)? Old with High AFC (OH; age 32 ± 2 years and 29 ± 7 follicles)? Young with Low AFC (YL; age 24 ± 2 years and 8 ± 2 follicles)? Old with Low AFC (OL; age 34 ± 1 years and 7 ± 1 follicles). Total RNA from each oocyte independently was isolated, amplified, labeled, and hybridized on HTA 2.0 arrays (Affymetrix). One sample from group Young with Low AFC (YL) was excluded due to apparent data quality issues. Remaining data were analyzed using TAC software and qPCR was performed to validate arrays.