P-072 Efficacy of a microfluidic chip technology for sperm selection in intrauterine insemination cycles
Authors: Moutos C , Kocur O , Xie P , Rosenwaks Z , Palermo G 
Published: June 2023

Abstract

Study question
Is there an advantage of using a new sperm selection method by microfluidics (MFSS) over standard density gradient (DG) for couples undergoing intrauterine insemination (IUI)?

Summary answer
MFSS reduced sperm processing time and selected spermatozoa with greater progressive motility and superior genomic integrity, suggesting a better clinical outcome than DG.

What is known already
The most conservative, cost-effective reproductive treatments for infertile couples are timed intercourse and IUI. The latter is generally performed using DG to enrich and purify the most motile spermatozoa; it requires technician effort and skills as well adequate processing time. Moreover, during DG centrifugation, spermatozoa are exposed to potentially harmful silica gel particles and eventual reactive oxygen species (ROS). The recent availability of a microfluidic chamber has been proposed as a method to safely process spermatozoa in an expedited manner while reducing human intervention. Therefore, we decided to test MFSS in a laboratory that executes over 2,000 IUI cycles/year.

Study design, size, duration
Since September 2022, 93 couples underwent 103 IUI-MFSS. Post-processing semen parameters and clinical outcomes were compared with those of 103 age-matched couples who underwent 103 IUI-DG during the same period. To confirm findings, 45 couples undergoing their first IUI-MFSS had post-processing semen parameters and clinical outcomes compared with 45 first-time IUI-DG couples, serving as a matched control. Finally, within the same 66 couples, outcomes were compared between their initial IUI-DG cycle and a subsequent IUI-MFSS.

Participants/materials, setting, methods
Men had normal raw semen parameters according to the most recent WHO criteria. DG was performed according to WHO21 guidelines, while MFSS as per manufacturer protocol (ZyMōt® Multi 850µL). Stimulation protocols were similar between all patients. Before and after processing, volume, concentration, and motility were compared between the two processing methods. Sperm chromatin fragmentation (SCF) was assessed by TUNEL (In Situ Cell Death Detection Kit; normal threshold,≤15%). For all comparisons, +bHCG and clinical pregnancy (+FHB) were compared retrospectively.

Main results and the role of chance
Ninety-three couples (maternal age,37.3±4; paternal age,39.2±6) underwent 103 IUI-MFSS cycles and were matched for age and abstinence days (1–4d) to 103 IUI-DG patient/cycles. IUI-DG and IUI-MFSS yielded 0.5±0mL volume, 76.8±40x106/mL and 41.3±26x106/mL concentrations, and 89.4±3% and 98.3±1% motility, respectively (P&lt;0.001). IUI-DG resulted in a 20.4% +bHCG (21/103) and 15.5% +FHB (16/103). IUI-MFSS yielded a 19.4% +bHCG (20/103) and 16.5% +FHB (17/103).
Forty-five couples (maternal age,36.8±4; paternal age,37.8±6) who underwent their first IUI with MFSSwere matched to a first-time IUI-DG cohort with similar semen parameters and abstinence. IUI-DG led to a 0.5±0 mL volume, 77.3±43x106/mL concentration, and 90±2% motility. IUI-MFSS yielded a lower concentration (45.6±27x106/mL), but a remarkable increase in motility (98.3±1%) (P&lt;0.001). IUI-DG yielded a 13.3% +bHCG (6/45) and an 8.9% +FHB (4/45). IUI-MFSS yielded a 15.6%(7/45) +bHCG and an 11.1% +FHB (5/45).
Finally, we assessed 66 couples who underwent IUI-DG and subsequently IUI-MFSS. IUI-DG resulted in a 77.5±39x106/mL concentration and 89.0±3% motility, while IUI-MFSS resulted in a lower concentration (36.9±21x106/mL), but an enhanced motility (98.3±1%)(P&lt;0.001). IUI-DG yielded a 15.2% +bHCG (10/66) and an 8.9% +FHB (5/66), while IUI-MFSS yielded a 15.2% +bHCG (10/66); all became clinically pregnant.
In all comparisons, SCF was 6.5±3% in raw samples, became 4.7±2% after DG, and negligible after MFSS at 0.8±0.6%(P&lt;0.001).

Limitations, reasons for caution
IUI-MFSS cycles yielded a higher number of progressively motile spermatozoa with superior genomic integrity and a comparable clinical outcome to IUI-DG. This study came at a higher cost due to the device and offered only preliminary results. Therefore, it needs to be repeated in a larger study population.

Wider implications of the findings
DG is time consuming, labor intensive, and its outcome is technician-dependent. While reducing exposure to chemicals and ROS, MFSS grants higher motility and superior genomic integrity. If a greater clinical outcome is confirmed in a larger cohort, MFSS may prove to be a superior sperm processing method for IUI.

Trial registration number
not applicable