Cumulus matrix selection leads to isolation of spermatozoa with better motility, morphology, and lower DNA fragmentation

Abstract

The objective of this study was to compare the motility, morphology, and levels of DNA fragmentation of spermatozoa subjected to conventional swim-up or cumulus matrix (CM) sperm selection. Semen samples were collected from 60 normozoospermic men at a private hospital between December 2021 and March 2022. After liquefaction, semen samples were separated into two portions – one part was subjected to conventional swim-up preparation, and the remaining spermatozoa were subjected to CM selection. The CM was obtained by mechanical isolation from healthy donor oocytes. Semen analysis and evaluation of sperm were performed according to the WHO 6th Edition Laboratory Manual and Kruger’s strict criteria, respectively. Sperm DNA fragmentation (SDF, %) of the two preparations was evaluated using the Halosperm G2 detection Kit (Halotech, Madrid, Spain). Wilcoxon rank-sum test was used to compare the characteristics of spermatozoa obtained by the two preparations. Spermatozoa selected by CM showed significantly better rapidly progressive motility (43.5% vs 30.6%, respectively, P < 0.001), a higher percentage of morphologically normal forms (14.0% vs 9.0%, respectively, P < 0.05), and lower levels of SDF (26.0% vs 45.0%, P < 0.05) compared to those prepared by conventional swim-up. Moreover, the incidence of multiple sperm defects was considerably lower in the samples that underwent CM selection compared to those that did not (30.0% vs 49.0%, respectively, P < 0.05).The selection by CM significantly increases sperm motility and reduces morphologically abnormal spermatozoa and DNA fragmentation rates compared to the conventional swim-up preparation. The application of this selection technique may increase the chances of successful IVF outcomes. Lay summary There are various techniques for selecting high-quality sperm with better shape, mobility, and DNA quality. However, the success of assisted reproduction techniques remains relatively unchanged. In this study, we describe an innovative method that uses the ingredients of a natural coat surrounding the egg (cumulus matrix) to enhance sperm selection procedures. Using this cumulus matrix as a barrier through which sperm cells pass, we mimic natural sperm–egg interactions and are able to select sperm with better characteristics compared to conventional methods. This new sperm selection procedure could lead to increased assisted reproduction success rates.