Differing molecular response of young and advanced maternal age human oocytes to IVM

• Published in: Human reproduction (Oxford) 2017-11, Vol.32 (11), p.2199-2208
• Main Authors: Reyes, J M, Silva, E, Chitwood, J L, Schoolcraft, W B, Krisher, R L, Ross, P J
• Format: Article
• Language: English
• Subjects: Adult; Age Factors; Female; Humans; In Vitro Oocyte Maturation Techniques - methods; Infertility, Female - genetics; Infertility, Female - metabolism; Infertility, Female - therapy; Maternal Age; Oocytes - metabolism; Original; Ovulation Induction; Transcriptome; Young Adult
• ISSN: 0268-1161; 1460-2350
• DOI: 10.1093/humrep/dex284

Abstract STUDY QUESTION What effect does maternal age have on the human oocyte's molecular response to in vitro oocyte maturation? SUMMARY ANSWER Although polyadenylated transcript abundance is similar between young and advanced maternal age (AMA) germinal vesicle (GV) oocytes, metaphase II (MII) oocytes exhibit a divergent transcriptome resulting from a differential response to in vitro oocyte maturation. WHAT IS KNOWN ALREADY Microarray studies considering maternal age or maturation stage have shown that either of these factors will affect oocyte polyadenylated transcript abundance in human oocytes. However, studies considering both human oocyte age and multiple stages simultaneously are limited to a single study that examined transcript levels for two genes by qPCR. Thus, polyadenylated RNA sequencing (RNA-Seq) could provide novel insight into age-associated aberrations in gene expression in GV and MII oocytes. STUDY DESIGN, SIZE, DURATION The effect of maternal age (longitudinal analysis) on polyadenylated transcript abundance at different stages was analyzed by examining single GV and single in vitro matured MII oocytes derived from five young (YNG; < 30 years; average age 26.8; range 20–29) and five advanced maternal age (AMA; ≥40 years; average age 41.6 years; range 40–43 years) patients. Thus, a total of 10 YNG (5 GV and 5 MII) and 10 AMA (5 GV and 5 MII) oocytes were individually processed for RNA-Seq analysis. PARTICIPANTS/MATERIALS, SETTINGS, METHODS Patients undergoing infertility treatment at the Colorado Center for Reproductive Medicine (Lone Tree, CO, USA) underwent ovarian stimulation with FSH and received hCG for final follicular maturation prior to ultrasound guided oocyte retrieval. Unused GV oocytes obtained at retrieval were donated for transcriptome analysis. Single oocytes were stored (at −80°C in PicoPure RNA Extraction Buffer; Thermo Fisher Scientific, USA) immediately upon verification of immaturity or after undergoing in vitro oocyte maturation (24 h incubation), representing GV and MII samples, respectively. After isolating RNA and generating single oocyte RNA-Seq libraries (SMARTer Ultra Low Input RNA HV kit; Clontech, USA), Illumina sequencing (100 bp paired-end reads on HiSeq 2500) and bioinformatics analysis (CLC Genomics Workbench, DESeq2, weighted gene correlation network analysis (WGCNA), Ingenuity Pathway Analysis) were performed. MAIN RESULTS AND THE ROLE OF CHANCE A total of 12 770 genes were determined to be expressed