Evaluation of telomere length in cumulus cells as a potential biomarker of oocyte and embryo quality

Abstract

Is the relative telomere length in cumulus cells associated with embryo quality and the subject's age? The relative telomere length in cumulus cells at the time of oocyte collection may be a new potential biomarker for selecting highly competent oocytes and good quality embryos. Telomeres play central roles in aging and in determining cell fate. In mammalian ovarian follicles, maturing oocytes are nurtured and supported by surrounding somatic cells, the mural granulosa and cumulus cells. A total of 350 oocyte-cumulus complex samples were collected from 80 IVF cycles prospectively recruited for this study at the Lee Women's Hospital, Taichung, Taiwan. Cumulus cells were manually separated from the oocyte-cumulus complex under a microscope. DNA was extracted from cumulus cells and assessed for telomere length by real-time quantitative PCR. We analyzed telomere length relative to a single copy marker gene (36B4) to evaluate the effect of the real reproductive age of cumulus cells on oocyte and embryo development. The relative telomere length was longer in cumulus cells from mature oocytes compared with cumulus cells from immature oocytes, and in cumulus cells from good-quality embryos compared with cumulus cells from poor-quality embryos. The cut-off value of the T/S ratio between good and poor-quality embryos on embryonic Day 3 was 4.235. Only a limited number of cumulus cells were measured for each oocyte and the corresponding embryo. The relative telomere length in cumulus cells at the time of oocyte collection is predictive of highly competent oocytes and good-quality embryos but may not be sufficiently discriminating to be clinically useful. National Science Council, Taiwan (NSC 97-2314-B-040-018). The authors have no conflicts of interest to declare.