P-176 A novel electrophoretic sperm isolation system achieves equivalent ICSI outcomes to the combined density gradient centrifugation and swim-up method in a significantly shorter processing time
Authors: Kitahara S , Mizuta S , Iwamoto Y , Doi K , Ohara Y , Matsubayashi H , Bakos H  W , Aitken R  J , Ishikawa T 
Published: July 2024

Study question

Does an electrophoretically sperm isolation method, the Felix™ system, have clinical or operational advantages over the combined density gradient centrifugation and swim-up (DGCS) method?

Summary answer

The Felix™ system produces results that are comparable to the DGCS method, however, Felix™ has the ability to isolate spermatozoa more efficiently.

What is known already

The isolation of healthy spermatozoa to improve ART outcomes has received enormous attention in the literature recently. Although swim-up and density gradient centrifugation are the most common sperm separation methods, the optimal technique is still unclear. Recently, good sperm selection approaches using various non-centrifugal devices have emerged. Previous reports have shown that a quick and simple sperm separation device, the Felix™ system, can isolate high-quality spermatozoa and improve the results of ART. The Felix™ system combines electrophoresis and separation membranes to collect negatively charged mature normal sperm.

Study design, size, duration

A prospective oocyte sibling study was conducted between March 2023 and December 2023. The study involved infertile couples (n = 45) with a semen volume of 2.3 mL or more, a motile sperm concentration of 2 million/mL or more, maternal age under 43 years, and at least four mature oocytes at the time of oocyte retrieval. Ejaculated semen was prepared separately using DGCS and Felix™ on the day of oocyte retrieval and subsequent ICSI results were analyzed.

Participants/materials, setting, methods

In the DGCS group, semen was layered on a 45/90% of sperm grad and centrifuged for 15 minutes, followed by a 30 min swim-up. Subsequently, 0.3 mL of supernatant was collected. In the Felix™ group, 0.3 mL of sperm was collected following six minutes of membrane hydration and electrophoresis. Sperm concentration, total motility, progressive motility and DNA fragmentation (SDFR) were measured. Fertilization, blastocyst development, good-quality blastocyst development, and embryo utilisation rates were also assessed.

Main results and the role of chance

The average female age at the time of oocyte retrieval was 36.5±4.0 years, and the average male age was 38.1±5.9 years. Of 401 oocytes, 200 and 201 oocytes underwent ICSI using sperm prepared by DGCS and Felix™, respectively. The average processing time of Felix™ was significantly shorter than that of DGCS (54.0±4.3 vs. 7.4±0.2 minutes, p &lt; 0.001, respectively). No significant difference was observed between the DGCS and Felix™ groups for sperm concentration (p = 0.49), motility (p = 0.05), progressive motility (p = 0.34), and SDFR (p = 0.09). Furthermore, there were no significant differences between the two groups with regards to fertilization rate (81.0% vs. 80.6%, p = 0.92), blastocyst development rate (52.9% vs. 58.4%, p = 0.60), good-quality blastocyst development rate (26.1% vs. 35.7%, p = 0.06), and embryo utilisation rate (54.3% vs 58.0%, p = 0.50).

Limitations, reasons for caution

Although the DGCS method was used as a comparison group, it is necessary to compare the Felix™ system with DGC alone, swim-up alone, or other sperm isolation methods. Larger, more powered studies are required to determine the impact on pregnancy and live birth outcomes.

Wider implications of the findings

The Felix™ system is a viable option for sperm isolation. While DGCS requires complicated procedures and time-consuming process including centrifugation and incubation; Felix™ requires six minutes only. The Felix™ system reduces processing times significantly and therefore can improve laboratory operations and workflow.

Trial registration number

Not Applicable