Chip selects best-performing sperm by getting them to swim upstream
When performing artificial insemination, the better the motility of the sperm, the greater the chances of a successful pregnancy. That's where a new microfluidic chip comes in, as it selects only the most vigorous, "highly-motivated" sperm from the herd.
Developed by a team at Florida Atlantic University, the microscope-slide-like tool consists of four sections: a fluid inlet chamber at the top, followed by a collecting chamber, sample inlet chamber, and a waste collection chamber at the bottom. They're sequentially linked by narrow microchannels.
The sorting process begins with a syringe being used to pump human tubal fluid (from the fallopian tubes) into the fluid inlet chamber, while a raw semen sample is placed in the sample inlet chamber.
As the liquid flows down the length of the chip, it creates a current. In a reaction known as rheotaxis, the sperm turn to face into that current, and set about swimming up to its source. Sperm naturally do so in the female reproductive system, wherein they swim against the cervical mucus flow in order to reach and fertilize the egg.
In the chip, the healthier, better-swimming sperm are able to make their way up to the collecting chamber, from which they're gathered for use in artificial insemination. Their dead or otherwise immotile counterparts, on the other hand, get carried downstream by the current, into the waste collection chamber.
Traditionally, a centrifuge is utilized to separate the most motile sperm from others. According to the Florida Atlantic scientists, however, sperm are often damaged in the two-hour process, resulting in oxidative stress and DNA fragmentation. By contrast, sperm gathered from the chip showed very little such damage, with almost 100 percent of them being highly motile and viable.
And as an added bonus, the sorting process takes just one hour, and requires little training … plus the chip is cheap to manufacture.
"The assembly of the microfluidic chip is low-cost, and the reagents used in the chip to separate sperm cells are only a few milliliters, therefore the commercial cost of the chip would be less than $5," said the lead scientist, Assoc. Prof. Waseem Asghar. "Moreover, this technology will considerably reduce the economic burden of fertility implementations, and both the chip and the sperm cells isolated from it offer great clinical significance and applicability."
The research is described in a paper that was recently published in the journal Analyst.
Source: Florida Atlantic University