O-295 Passive sperm sorting does not select for sperm with lower DNA fragmentation levels compared to density gradient centrifugation in split samples
Authors: Weldon K , Bravo Martin R , Moran C , Keane D , Sloan A , Abril-Parreño L , White E , O'Sullivan L , Newport D , Lewis S , Fair S 
Published: June 2022

Abstract

Study question
Does the passive sperm separation device, Zymot, select sperm with lower DNA fragmentation levels compared to Density Gradient Centrifugation (DGC)?

Summary answer
The sperm separation device Zymot did not select sperm with lower DNA fragmentation levels compared to sperm selected by DGC or the neat sample.

What is known already
Previous studies have shown that sperm with high DNA fragmentation levels result in lower fertilisation rates, impaired embryo development, lower pregnancy rates and increases the risk of miscarriage. Currently, prior to fertility treatment, the method of choice for sperm selection is using DGC, which involves the centrifugation of sperm. Therefore, there is a clinical need for a sperm selection method that avoids centrifugation, while mimicking the natural process of sperm selection in the female reproductive tract and selects sperm with intact DNA.

Study design, size, duration
This blinded controlled study included 29 patients from which semen samples were obtained between May 2021- January 2022 at ReproMed fertility clinic (Dublin, Ireland). Ejaculates were split and processed using either DGC, passive separation device (Zymot; 850 uL) or unprocessed (neat; control) and assessed for sperm quality in terms of motility (progressive, non-progressive and immotile), morphology and DNA fragmentation (assessed using the COMET assay). Two hundred sperm were assessed for each analysis.

Participants/materials, setting, methods
Motility and morphology were assessed using microscopy techniques as per WHO guidelines. DNA fragmentation was assessed using the COMET assay and each sample was given an Average COMET score (ACS), Low COMET score (LCS) and High COMET score (HCS). All data were checked for normality of distribution following which they were analysed using analysis of variance (ANOVA) with Bonferroni post-hoc tests. All values presented are mean ± standard error of the mean.

Main results and the role of chance
Sperm sorted by the Zymot device had higher progressive motility (78.7 + 3.42%) than both the neat (53.3 + 3.40%) and DGC (51.8 + 3.74%%) samples (P &lt; 0.001). Sperm selected by DGC had a greater percentage of sperm with non-progressive motility (16.0 + 2.02%) compared to the neat sample (8.6 + 1.11%) and the Zymot device (9.9 + 1.60%). The overall percentage of normal morphology in the neat sample was 4.3 + 0.16% and there was no effect of sperm selection method on the percentage of sperm with normal morphology (P &gt; 0.05). The ACS in the neat sample was 32.5 + 1.48% and neither DGC (28.2 + 1.45%) or Zymot (29.1 + 1.50%) improved this (P &gt; 0.05). In line with this, neither LCS nor HCS differed between the treatments (P &gt; 0.05).

Limitations, reasons for caution
A higher number of patient samples are needed to validate the efficacy of the Zymot sperm separation device on DNA fragmentation levels. Also, targeting patients with higher DNA fragmentation in the neat sample may yield greater benefits.

Wider implications of the findings
The results of this study indicate that the passive sperm selection device, Zymot, selects more motile sperm but does not select sperm with intact DNA. There is a need for a non-cell destructive method to select sperm with intact DNA to improve the outcomes for couples undergoing fertility treatment.

Trial registration number
Not Applicable