EXCESS REACTIVE OXYGEN SPECIES IN EJACULATE AFFECT EMBRYO DEVELOPMENT IN VITRO WHEN ASSISTED REPRODUCTIVE TECHONOLOGIES ARE USED

Abstract

Background. Reactive oxygen species are a necessary condition for the maturation, existence and ability of spermatozoa to fertilize the oocyte. The excess reactive oxygen species in semen can initiate pathological changes in sperm, causing oxidative damage to cell membranes, proteins, and DNA. The aim of the present study was to investigate changes in standard microscopic parameters and the level of ROS in the ejaculate in men with low reproductive function, to determine the influence of paternal age on the mentioned parameters, and to establish a possible relationship between the level of ROS generated in the sperm and an early embryonic development in infertile patients.
Materials and Methods. The development of the embryos from 26 married couples with combined factors of infertility was analyzed. Microscopic analysis of the ejaculate was performed according to the WHO recommendations from 2021. The level of oxidative stress in the ejaculate was analyzed using Oxisperm kits (Halotech DNA, Spain). Donor oocytes were fertilized by the method of intracytoplasmic sperm injection (ICSI). Embryos that reached the blastocyst stage were evaluated by morphological characteristics accor­ding to the criteria of D. Gardner (2000). Preimplantation genetic testing of blastocysts for aneuploidy was performed using the next-generation sequencing method. Statistical hypotheses were tested using the chi-square and r_s criteria at significance levels of 0.05 and 0.01.
Results and Discussion. The present study demonstrates the negative effect of the excess of ROS in the ejaculate on early embryo development and embryo ploidy. Increased ROS level negatively affects both total blastocyst formation rate (r_s = -0.66, p = 0.00247) and euploid blastocyst formation rate (r_s = -0.65, p = 0.04034). Among the infertile patients the part of men with an excess of ROS in ejaculate is significantly higher compared with sperm donors (p = 0.000063). A significant negative correlation was found between sperm motility and paternal age (r_s = -0.54, p = 0.01795). No correlation was observed between ROS levels in the ejaculate and sperm motility, concentration, and morphology in infertile patients.
Conclusion. The negative influence of the excess of reactive oxygen species in semen on the early embryo development in vitro has been proved. A negative effect of increased ROS levels on male reproductive function has been demonstrated. Excess of ROS in ejaculate results in a decrease of both total blastocyst formation rate (r_s = -0.66, p = 0.00247) and euploid blastulation rate (r_s = -0.65, p = 0.04034). A negative effect of paternal age on microscopic sperm parameters has been shown. An excess of ROS in sperm does not lead to fertilization failure in ICSI. No correlation was found between microscopic sperm parameters and early embryo development in vitro.