P-180 Hyaluronidase used in oocyte denudation inhibits the proliferation and the viability of cumulus cells through the inhibition of midkine

Abstract

Abstract Study question Does hyaluronidase (HAse) have possible negative or positive effects on cumulus cells (CCs) during oocyte denudation before ICSI by altering midkine (MK) levels? Summary answer Hyaluronidase inhibits the proliferation of CCs via the inhibition of MK activity which may result in poor embryo quality and low ICSI success. What is known already MK is abundantly expressed in ovarian follicles. MK secreted from the cumulus-granulosa cells that surround oocytes was shown to promote the cytoplasmic maturation of oocytes. This effect of MK could be mediated via its' anti-apoptotic effect and some other mechanisms. The removal of CCs during oocyte denudation (OD) is done in order to select and grade the oocytes before ICSI. HAse is applied for ICSI to break down hyaluronic acid, which is present at high levels in the cumulus-oocyte complex during OD. To date, there have only been a few reported cases of the toxic effects of hyaluronidase on oocytes. Study design, size, duration This study is a prospective, randomized study done with 90 healthy women between September 2017 and September 2018. Participants/materials, setting, methods This study was done with women diagnosed as a male factor between the ages of 21 and 40 who underwent ICSI. HAse was applied to the cultured CCs at concentrations of 0.1 IU/ml, 1 IU/ml, and 10 IU/ml. The proliferation and apoptosis indices (Flow cytometry), structures [Transmissive electron microscopy (TEM)], and MK levels (ELISA) of CCs were evaluated every 24 hours for 48 hours. One way-Anova was used and p < 0.05 was considered statistically significant. Main results and the role of chance The application of HAse at all concentrations decreased cumulus cell numbers for 48 hours (p < 0.05). The highest decrease in cell number and cell viability with the highest number of apoptotic cells were detected at the 48th hour at the application of the highest concentration of HAse (p < 0.05). The highest concentration of HAse application caused the highest decrease in MK levels at the end of 48 hours (p < 0.05). Limitations, reasons for caution The effect of HAse on the CCs of women aged below 21 and above 40 could not be evaluated. Therefore, the overall resistance and fragility of CCs to these HAse concentrations could not be evaluated. In addition, the HAse effects should be evaluated in female infertility cases such as PCOS. Wider implications of the findings This is the first report to examine the effect of HAse on MK activity. 2-3 lines of CCs are commonly left during oocyte denudation in order to protect the oocyte from stress-induced reactions. The low number of CCs means low MK levels resulting in a loss in oocyte competence. Trial registration number Tthe Ethics Committee Directive on Non-Interventional Studies of Biruni University with the permission numbers 2017/5-1.