Evaluation of the Efficacy of the modified Swim-Up Technique for sperm sex sorting

Abstract

The development of non-invasive approaches for the sperm sex sorting remains an area of considerable interest in assisted reproductive technologies. Although X- and Y-bearing spermatozoa are genetically distinct, the subtle differences in their physical characteristics can be exploited for sperm sex enrichment remains controversial. The swim-up technique primarily selects spermatozoa depending on motility and migration capacity and may therefore provide a potential basis for differential enrichment when its conventional protocol is appropriately modified. By using this technique, the faster spermatozoa can be separated which are believed to carry a higher percentage of Y- chromosome based on hypotheses proposed first in the sixties of last century.This prospective study aimed to comparatively evaluate the modified swim-up based techniques to differentially enrich Y-chromosome-bearing spermatozoa in human semen samples and to determine whether modification of sperm migration conditions could induce a measurable shift in the Y bearing spermatozoa ratio. The study included 93 couples, undergoing ICSI/PGT-A protocol, involving 93 semen samples and a total of 1247 oocytes divided into 2 groups. Semen samples were obtained from 93 participants and analysed according to standard laboratory criteria. Each sample subjected to a modified swim-up protocol designed to enhance the selection of highly progressive motile spermatozoa. After ICSI procedure and embryo formation, the proportions of XY and XX yielded embryos were determined using NGS technique. As a result, the higher proportion of XY embryos was associated with swim-up techniques with a percentage of 39.34%, compared to the non-swim-up approaches (31.98%), and the difference was statistically significant with a p-value of 0.025. These findings indicate that sperm migration under the modified conditions was associated with differential enrichment rather than absolute separation of X- and Y-bearing sperm populations.