P-059 Euploidy and mosaics rates using microfluid sperm selection techniques (Zymot-ICSI®)
Authors: Cortés Gallego S , Arasa M , Andrés Santé C , Cordero C , Rodriguez-Roque C , Almoyna A , Navarro H , Horcajadas J 
Published: July 2024

Study question

Can Zymot-ICSI® influence the mosaic embryos rate? Is the degree of doble strands DNA fragmentation (dsSDF) affecting euploidy and mosaicism outcomes?

Summary answer

The use of Zymot-ICSI® in seminal samples induces a decrease in aneuploid embryos, and an increase in euploid and/or mosaic embryos independently of the dsSDF.

What is known already

It has been demonstrated that sperm with higher motility exhibit superior genomic integrity, establishing a direct relationship between dsSDF and the capacity for embryonic development and implantation. In a previous study focused on investigating differences in a various biopsy techniques and their impact on the genetic outcome of the embryos, an increase in the number of mosaic embryos was identified. The main objective of this study is to ascertain whether sperm selection using these techniques, specifically the use of Zymot-ICSI®, increase the euploidy rate in patients with altered fragmentation indices, and its relations with mosaics distribution.

Study design, size, duration

A retrospective study analyzed a total of 684 biopsied embryos in 2021, of which 339 came from seminal samples without COMET test, and 345 embryos came from seminal samples that underwent the COMET test, analysing the sperm DNA fragmentation with one DNA strand (ssSDF) and double DNA strands (dsSDF). Genetics analysis of these 345 embryos were divided into 3 groups according to the techniques used in the sperm selection before ICSI (dsSDF: &lt;60; 60-80; &gt;80).

Participants/materials, setting, methods

Differences between Swim-up/gradients(Sw/G)(n = 513) and Zymot-ICSI®/Sperm-Slow(n = 171) were assessed. 309 embryos without COMET prior to ICSI, underwent Sw/G, 5 sperm-slow and 20 Zymot-ICSI® (both prophylactically). In cases where fragmentation was high and Zymot-ICSI®(n = 98) could not be performed before ICSI for low sample quality, Sperm-slow(n = 10) or Sw/G(n = 199) techniques (with normal or altered fragmentation) were used. The existence of variations in the type of mosaicism (Simple/Complex) was also analysed with respect to the sperm selection technique used and dsSDF.

Main results and the role of chance

No significant differences were observed between the different sperm selection techniques used (regardless of the degree of dsSDF), in terms of euploidy, aneuploidy and mosaic values (p:0.861). According to the dsSDF, the usefulness of Zymot-ICSI® versus Sw/G is shown, decreasing the percentage of aneuploid embryos IF &lt; 60 (20% vs 44.1%); IF &gt; 80 (28.6% vs 43.8%), increasing the percentage of euploid embryos in IF &lt; 60% (60% vs 46.5%) and maintaining them in IF &gt; 80 (52.4% vs 50%). However, an increase in mosaics was observed in all the groups studied (depending on the sperm selection technique Zymot-ICSI® vs Sw/G) but independently of the dsSDF: &lt;60: 20% vs 9.30%; 60-80: 13.4% vs 9.62%; &gt;80: 18.2% vs 5.88%. No differences were found between the different types of mosaic embryos (simple or complex) between the different groups according to the dsSDF (p &gt; 0.1), but there was a trend towards a decrease in complex mosaic embryos and an increase in simple mosaic embryos when using Zymot-ICSI® versus Sw/G (Complex Mosaic: 13% vs 23.2%; Simple Mosaic 87% vs 76.8%).

Limitations, reasons for caution

Although there is a trend towards an increase in mosaic embryos, the difference is not significant, probably due to the low number of samples in some cases.

Wider implications of the findings

Use of Zymot-ICSI® in seminal samples induces a decrease in aneuploid embryos, and an increase in euploid and/or mosaic embryos. The increase in mosaic embryos after the use of Zymot-ICSI® occurs independently of the dsSDF, observing a tendency towards a decrease in mosaic-complex embryos and an increase in simple embryos.

Trial registration number

Not applicable