Purpose: Our purpose was to establish an evaluation system for oocyte quality based on the incidence of cumulus cells apoptosis and to examine the effect of coculture, using autologous cumulus cells, on the outcome of IVF-ET according to proliferative activities of helper cells and the incidence of cumulus cells apoptosis.
Methods: Cumulus cell masses were collected from 91 mature oocytes among 330 oocytes retrieved from a total of 34 IVF-ET cycles with tubal infertility and unexplained infertility. The incidence of apoptosis in cumulus cells was assessed by apoptosis detection kit fluorescein. On ovum pick up, 2nd day embryos were cocultured with autologous cumulus cells. Prior to coculture, in vitro proliferative activity of cumulus cells was evaluated.
Results: Cumulus cells from patient groups over 40 years old had a significantly increased apoptosis incidence, a lower fertilization rate, and the decreased number of oocytes retrieved compared to the other age groups (P < .05). The incidence of cumulus cells apoptosis was significantly lower when the number of oocytes retrieved was 5 or less (P < .05). Cumulus cells from fertilized oocytes (0.43 +/- 0.07%) and those from patients who became pregnant (0.44 +/- 0.11%) following IVF-ET showed a significantly lower incidence of apoptosis compared to those of unfertilized oocytes (1.80 +/- 0.35%; P < .001) and the nonpregnant group (0.81 +/- 0.10%; P < .05). Embryo quality also had a negative correlation with the incidence of cumulus cells apoptosis. Coculture of fertilized oocytes with cumulus cells with high proliferative activity resulted in improved rates of implantation and pregnancy compared to that with poor active cumulus cells. No significant difference was found between the in vitro proliferative activity of cumulus cells and the incidence of cumulus cells apoptosis (P < .063).
Conclusions: The age of women might influence the incidence of apoptosis in cumulus cells, and the increased incidence of apoptosis is associated with the number of oocytes retrieved, the fertilization rate, and the pregnancy outcome following IVF-ET. These results suggest that the incidence of cumulus cells apoptosis can be used in predicting oocyte quality, outcome of IVF-ET, and age-related decline in fertility.