HYALURONIDASE INHIBITS MIDKINE IN CUMULUS CELLS DURING OOCYTE DENUDATION

Hyaluronidases are applied to break hyaluronic acid found in high levels in the cumulus-oocyte complex at the oocyte denudation for in vitro fertilization (IVF). The purpose of the study was to investigate whether midkine (MK) has a role at the proliferation and viability of cumulus cells (CCs) at the oocyte denudation done by using hyaluronidase. This was a prospective, randomized study done with 90 females aged 21-40 and diagnosed as a male factor undergoing intracytoplasmic injection (ICSI) from September 2017 to September 2018. CCs taken via mechanical applications from patients were cultured. Hyaluronidases at the concentrations of 0.1 IU/ml [The lowest concentration, (n:30)],1 IU/ml (n:30), and 10 IU/ml [The highest concentration, (n:30)] were applied to CCs. Every 24 hours of 72 hours, proliferation and apoptosis indeces (Flow cytometry) of CCs were evaluated with MK levels (ELISA). Ultrastructure of CCs (n:15 per group) was also evaluated by using Transmission Electron Microscopy (TEM). One way-Anova was used and p<0.05 was considered statistically significant. All concentrations decreased the cumulus cell numbers for 72 hours (p<0.05). The highest decrease in cell number was detected at the highest concentration (p<0.05) at the 72nd h. In concordance with this result, the highest increase in apoptotic and dead cell rates with the lowest viable cell rate was detected at the highest concentration (p<0.05) at the 72nd h. The highest level led to the highest decrease in MK levels at the 72nd h (p<0.05). The ultrastructural analysis showed that the number of apoptotic CCs was increased from the lowest concentration to the highest concentration. The inhibition of the proliferation and the viability of CCs by hyaluronidase through the inhibition of MK was firstly reported in this study. This may be one of the reason of poor oocyte quality which leads to the decrease in IVF success.