Human ovarian granulosa cell methylome

We used MethylCap-seq and RRBS to profile methylomes of purified human ovarian granulosa cells. Genomic DNA methylation patterns in ovarian granulosa cells were compared between two groups of women: i) oocyte donors (n=20) who were young (age 26 ± 2.2 years) and had robust response to ovarian stimulation during assisted reproductive technology (ART) (mean number of oocytes retrieved = 25); versus ii) poor responders (n=20) who were older (age 40 ± 2.3 years) and responded poorly to ovarian stimulation during ART (oocytes retrieved ≤4 and peak estradiol level ≤ 1000 pg/ml). The first group served as healthy control. The second group represented the majority of women in their early 40s who have the natural age-related decline of ovarian functions and therefore respond poorly to ovarian stimulation during ART. We compared DNA methylomes in ovarian granulosa cells from oocyte donors versus poor responders using two approaches: MethylCap-seq for broader genomic coverage, and RRBS for absolute quantification. Due to very limited amount of materials available from each poor responder, samples containing equal amounts of granulosa cell DNA were pooled from 10 individuals in each group. A second set of experiments pooling granulosa cell DNA samples from independent donor and poor responder groups (ten individuals each) was then performed. mix 10 individuals into one sample; compare samples with age differences