Relationship between embryo development and apoptotic gene expression of cumulus cells in poor responders and polycystic ovary syndrome

Research question: Is there a relationship between embryo quality, pregnancy rates and apoptotic gene expression in cumulus cells of oocytes collected from patients with poor ovarian response and polycystic ovary syndrome?

Design: Fifty infertile couples who underwent assisted reproductive technology treatment were included in the study (Approval date 4 February 2020, number 03). The patients were divided into four group: control (n = 9; 90 oocytes), unexplained infertility (n = 8; 86 oocytes), polycystic ovary syndrome (PCOS) (n = 6; 137 oocytes) and poor ovarian response (POR) (n = 27; 124 oocytes). Cumulus cells were isolated individually from 437 oocytes obtained. Intracytoplasmic sperm injection was undertaken on 365 mature oocytes. The embryos were monitored. Caspase-3, Bax and Bcl-2 gene expressions of the cumulus cells were measured by real-time polymerase chain reaction.

Results: A significant and negative correlation was found between Bax and Bcl-2 expressions of the cumulus cells of poor-quality embryos. The increase in Caspase-3 gene expression in the POR group statistically decreases the pregnancy rates. Fertilization and good-quality embryo development of 365 oocytes whose cumulus cells were examined, however, were not associated with apoptotic gene expression. The Bax/Bcl-2 ratio was found to be significantly lower in cumulus cells of mature oocytes.

Conclusions: Our results demonstrated no significant associations between fertilization, quality embryo development and apoptotic gene expression. Bax expression and the Bax/Bcl-2 ratio are high in immature oocyte cumulus cells has shown us that the apoptotic process may begin when the cumulus-oocyte connection exists.