Carbon Monoxide Exposure Does Not Improve The In Vitro Fertilization Rate of Oocytes Obtained from Heterozygous Hmox1 Knockout Mice

Abstract

In our experimental study we explored the impact of maternal reduced heme oxygenase-1 (HO-1) gene ( Hmox1) expression on the in vitro fertilization (IVF) rate through the use of heterozygous Hmox1 knockout mice models ( HET/Hmox1 ⁺/ ^- ). Also, we hypothesized a beneficial role of gametes exposure during fertilization to carbon monoxide (CO), one of HO-1 by-products, that might be relevant for the improvement of IVF rates. IVF technique was performed by using oocytes obtained from wild-type (WT) or Hmox1 ⁺/ ^- dams fertilized with WT, Hmox1 ⁺/ ^- or Hmox1 ^-/ ^- mice-derived sperm. The fertilization step occurred either in a conventional incubator (37°C, 5% CO2) or in an incubator implemented with CO (500 ppm). The superovulation yield of WT and Hmox1 ⁺/ ^- mice and the number of fertilized oocytes was assessed using an optical microscope. The dams’ Hmox1 heterozygous knockout neither impact the superovulation yield, nor did influence the fertilization success rate. Moreover, CO exposure during fertilization could not significantly improve the outcome. Our study showed that the maternal Hmox1 ⁺/ ^- condition is not affecting the IVF rate in mice. Furthermore, we discovered that CO exposure cannot be exploited to ameliorate this critical step of the IVF protocol.