Separation of sperm based on rheotaxis mechanism using a microfluidic device

In the application of assisted reproductive technologies (ART), selection of the optimal sperm presents a challenge. This study introduces an innovative microfluidic device that utilizes rheotaxis to efficiently sort sperm, offering superior selection of high-quality sperm compared to conventional methods.

We analyzed 30 normal samples from couples undergoing intracytoplasmic sperm injection cycles at the Infertility Center of Fatemieh Hospital in Hamadan, Iran. Each sample was divided into three groups: the initial sample, representing the control group; direct swimup sperm selection; and sperm selection using rheotaxis. A syringe pump connected to the microfluidic device generated optimal flow conditions. Spermatozoa were evaluated regarding concentration, motility, morphology, mitochondrial membrane potential (MMP), and sperm DNA fragmentation index (DFI). Statistical significance was determined using one-way analysis of variance and the Student t-test.

The concentration (7.46±2.84 million cells/mL vs. 56.67±18.27 million cells/mL, p<0.0001) and DFI (2.93±2.70 vs. 21.13±5.27, p<0.0001) were significantly lower in the sperm selected using the rheotaxis microfluidic device than in the control sperm. Progressive motility (98.10%±2.41% vs. 44.13%±7.06%, p<0.0001), normal morphology (8.36%±1.47% vs. 5.20%±1.15%, p<0.0001), and MMP (99.63%±0.71% vs. 81.13%±9.19%, p<0.0001) were significantly higher with the device than in the control group.

The use of a rheotaxis-based microfluidic device appeared effective in selecting high-quality sperm, demonstrating improvements in motility, morphology, and MMP and a reduction in DFI. This advancement has the potential to improve the outcomes of ART.