DOES ZYMŌT SPERM SEPARATION IMPROVE EMBRYO DEVELOPMENT OUTCOMES WHEN APPLIED TO ALL INFERTILITY PATIENTS COMPARED TO DENSITY GRADIENT WASHING OR SURGICALLY ATTAINED SPERM

Objective: The ZyMōt sperm separation device has proven favorable for use in elevated DNA fragmentation index (DFI) male factor patients, as an alternative to density gradient (DG) washing or surgically attained testicular sperm. In 2020, without fully understanding the infectivity and transmission potential of SARS-CoV2 in semen, a more liberal application of a timed ZyMōt microfluidic swim-up was applied to our IVF patients to dilute out and minimize potential pathogens. This study aimed to evaluate whether the use of ZyMōt sperm improved normal embryo development. Materials and Methods: Retrospective analysis of PGT-A/ICSI cycles (N= 3219) between 2016-2020 was conducted to assessed fertilization rates (FR), blastocyst development/utilization rates (BUR) and genetic outcomes. Sperm preparations were performed per standard operating or manufacturer advised (i.e., ZyMōt) procedures. Cumulus oocyte complexes were harvested 36h post-hCG, stripped and ICSI performed 3-5hr later. Zygotes were assessed at 16-18hr post-ICSI, and embryos cultured under humidified tri-gas incubation for up to 7 days. Blastocyst (BL) development as evaluated, and expanded BL or greater were biopsied on Days 5, 6 or 7. All BL were vitrified and genetics determinations for euploidy, aneuploidy and mosaicism were contrast. Applying Chi-squared analysis, we compared potential differences (p<0.05) between oocytes inseminated by DG wash (n=23,549), ZyMōt wash (n=7,331) or testicular sperm (n=815). Results: No difference in FR (76%), D5 BL formation (52-56%) or BUR (52-53%) was detected between DG and ZyMōt washed sperm, respectively. Meanwhile, testicular sperm had a lower FR (70%;p<0.05), fewer BL forming on D5 (48%;p<0.05) and a lower overall BUR (41%;p<0.05). In addition, fewer testicular-derived BL were euploid (39%;p<0.05) with more aneuploidy (54%;p<0.05) than DG wash (50%, 39%;respectively) or ZyMōt swim-up (45%, 37%;respectively) derived-embryos. No difference in potentially viable BL (Euploidy+Mosiac outcome) was observed between DG or ZyMōt wash groups (63-64%). Conclusions: Application of the ZyMōt device in the general IVF population offered no benefit to embryo development outcomes compared to standard sperm wash procedures. Our data does support that microfluidic separation of sperm using ZyMōt for male factor patients with elevated DFI is a more favorable and cost-effective approach to surgically attaining testicular sperm when ejaculated sperm is possible. However, when insufficient motile and or morphologically normal sperm are available in an ejaculate further analysis is needed to elucidate the benefit of testicular biopsy treatment, as our assessments in this study may be biased by including men with non-obstructive azoospermia. Impact Statement: The timed selection of morphologically normal, highly progressive sperm by ICSI, PVP-swim-out likely mimics the potential benefits the ZyMōt device may offer infertile men with elevated sperm DNA fragmentation generating similar blastocyst development and euploidy outcomes.