Viable sperm developed from monkey stem cells.

Male infertility can be a challenging health issue, with 12 percent of men in the United States unable to produce healthy sperm capable of fertilizing an egg. To date, the many causes of this upsetting condition include genetic defects, environmental toxicants, injuries, or medical treatments such as chemotherapy. However, regardless of the origin, men who can’t produce viable semen have limited options when using reproductive aids – because these technologies need feasible seminal fluid to work.

A change has now come in the guise of a study led by researchers from the University of Georgia (UGA). The trial, published in Fertility and Sterility Science, shows that functional sperm can be produced in the laboratory using stem cells from monkeys. “This is a major breakthrough towards producing stem cell-based therapies to treat male infertility in cases where the men do not produce any viable sperm cells,” said Charles Easley, an associate professor in UGA’s College of Public Health.

Recent work from the team used stem cells from mice to produce immature sperm cells that do not have a head and a tail for swimming, known as spermatids. But rodent semen production is very distinct from homo sapiens due to essential genetics. Meaning it was unclear whether this technique could help men suffering from infertility – leaving the team looking for a better solution. The answer came in the shape of rhesus macaque monkeys who share similar reproductive apparatus to humans. These procreant parallels made them a suitable model for exploring stem cell-based therapies for male infertility.

In the new study, the team used embryonic stem cells from the macaques to generate spermatids. After which, the immature reproductive cells successfully fertilized a rhesus monkey egg. And just like their native counterparts in vivo, reproduction in a glass dish also requires inseminating the egg in the correct environment for the zygote to develop into a healthy embryo.

Commenting on this significant stage in establishing whether clinicians can use lab-made spermatids in human reproduction, Easley states: “This is the first step that shows this technology is potentially translatable. We’re using a species that’s more relevant to us, and we’re having success in making healthy embryos.”

The researchers now plan to implant these monkey embryos into surrogate mothers to examine whether they produce healthy babies. If this is successful, the team will carry out the same process using immature sperm cells derived from macaque skin cells – and from here, the work can begin on humans.

Source: University of Georgia

Image courtesy of Wirestock on Freepik

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