Sperm Analysis and Selection

Infertility is a growing global health problem. The downward trend in male fertility highlights the urgent need for affordable and accessible diagnosis and treatment. In the diagnosis and treatment of male infertility, there are many emerging opportunities for microfluidic technology to solve male infertility. Microfluidic methods can improve researchers' basic understanding of sperm movement, and the development of microfluidic devices that use micromachining and sperm behavior can help semen analysis and sperm selection.

For biologists and clinicians, there are many emerging possibilities to improve current practice in the diagnosis and treatment of infertility. The most promising path may improve medical practice and transfer innovation from research laboratories to clinics and patients soon.

Microfluidics for Semen Analysis

The first step in treatment is diagnosis. Male infertility may be due to low sperm concentration, vitality, motility, and damage to DNA. Semen analysis is essential for the diagnosis and treatment of male infertility. The microfluidic chip is an alternative to the conventional manual process used for semen analysis. Several microfluidic devices have shown the ability to analyze key semen analysis parameters, such as sperm count, sperm motility, and sperm morphology. These techniques have proven to be fast, easy to use, and consistently accurate. The following summarizes some of the microfluidic techniques used for semen analysis.

Alfa Chemistry has many years of experience in prototyping and custom microfluidic manufacturing. We will be happy to discuss your project with you. Our semen analysis chip can be disposable and can be used for the home screening of patients. Patients can be screened for their progress without having to see a doctor in person.

Microfluidics for Sperm Sorting

Because the quality of sperm will affect the success rate of antiretroviral therapy, the rate of birth defects, and the potential infertility of male offspring, the choice of sperm is very important. Microfluidic technology provides the opportunity to sort sperm cells in a faster and gentler way, which can more closely mimic the natural selection process and avoid some of the most harmful factors in current sperm sorting technology. Microfluidic sperm sorting methods can generally be divided into the following three categories:

Microfluidic device for separating only motile sperm

This is the largest group of microfluidic devices and includes technology to improve swimming methods by converting the exercise screening process into a microfluidic system. Although some of these systems are able to select enough sperm cells for intrauterine insemination (IUI) (> 10 M sperm), most systems select smaller and purer subpopulations suitable for in vitro fertilization (IVF) (approximately 100000 cells). In general, the subpopulations selected by these systems have close to 100% motility and are of higher quality than unprocessed semen samples in terms of morphology and DNA integrity.

Fig.1 Microfluidic systems designed for separation of sperm based on sperm motility. (A) Motile sperm can be selected from immotile sperm due to their ability to swim across channel width; (B) motile sperm are selected and sorted by swimming speed using the imposed velocity gradient; (C) a series of parallel, long narrow channels are used to select motile, viable sperm. (Samuel R, et al. 2018)

Microfluidic device for separating sperm cells without relying on sperm motility

Such microfluidic devices use sperm shape, size, or other physical biomarkers as a trap/selection mechanism, which do not necessarily focus on capturing sperm subpopulations, but rather these systems have the potential to preserve the full fertilization capacity of subsperm samples by indiscriminately capturing sperm cells.

Fig.2 A microfluidic system designed for rapid separation of sperm from epithelial cells. (A) A picture of the actual device; (B) the cell mixture is aligned against the top wall in the pinched segment, and then the position difference of different sized cells is amplified in the expansion region; (C) sperm recovery rate is improved in the parallel capillary tubes. (Samuel R, et al. 2018)

Microfluidic device for observing and selecting individual sperm.

An emerging field of research on single sperm selection involves the combination of Raman spectroscopy and microfluidic sperm sorting systems. Raman spectroscopy on a single cell can be non-destructive and label-free, and can provide a lot of information about the molecular structure of the cell, which makes Raman spectroscopy very attractive for reproductive medicine. Viable sperm may have Raman spectra with common characteristics, leading to the realization of biomarkers.

Whether you are interested in fertility research or are seeking to develop current fertility technologies, Alfa Chemistry can assist you in all stages of device development.

Reference

• Samuel R, et al. (2018). "Microfluidic-based sperm sorting & analysis for treatment of male infertility." Transl Androl Urol. Suppl 3: S336-S347.

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