Infertile men given fighting chance as strongest sperm are sorted

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May 15, 2003 — The battle against infertility soon could have a friend in small tech.

University of Michigan researchers have developed prototype microfluidic devices that can automatically and rapidly sort sperm and isolate the most viable swimmers for injection into an egg. The Microscale Integrated Sperm Sorter does it all on one disposable device.

The ultimate goal is to create a self-contained, at-home test that men can use to screen for infertility or judge the success of vasectomy or vasectomy reversal procedures. In the nearer term, the devices could help clinics select the most viable sperm for in vitro fertilization. And they could do it in minutes, rather than the hours it can take in some situations using current technology.

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The technology comes from a U-M team led by biomedical engineering professor Shuichi Takayama, and the biological contributions came from a group led by Gary Smith, director of the university’s Assisted Reproductive Technologies Laboratory.

The device uses a passive pumping system based on gravity and surface tension, and the viable sperm are isolated using a sorting mechanism based on speed — the faster, or “motile” sperm can deviate from their path and exit through a different outlet. The researchers say the technique also could be safer than other macroscale sorting mechanisms like a centrifuge, which can damage sperm.

Takayama said his team had been developing microfluidic devices for different biomedical uses when Smith told him of the need for an automated sperm sorter. “We thought about that and worked out some design details,” Takayama said. “This was pretty straightforward.”

Microfluidic devices have been, or are being, developed for gender sorting in humans and animals. There also are color-based home sperm tests, but they look for total, not motile sperm, Takayama said.

He said it could be about a year for research applications to make it to market, but approvals for home use will take longer. He and his colleagues see the potential on both fronts and are discussing the best way to commercialize the technology. “We also think this is just the beginning of microfluidic technology that is functional but is readily accessible to a wide range of people,” he said. “We’re trying to make the technology something people don’t have to think about.”

Melissa Ivanovic, an embryologist with North Shore Fertility, a Chicago area clinic specializing in reproductive medicine and assisted reproductive technologies, said great strides have been made in fertilization techniques, but sperm preparation has not changed in the past 15 years.

She said that current systems involving filtration and centrifuges tend to work well, but new developments would be welcome for severe infertility, when isolating sperm is more difficult.


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