Lab-grown human sperm may ‘finish male infertility’ in big medical breakthrough
A startup says it has grown “functional” human sperm from testicular stem cells in a lab and used it to create healthy-looking embryos in a major breakthrough
Boffins may have found a solution to male infertility(Image: Getty Images)
Boffins may have found a solution to male infertility after they successfully grew human sperm in a lab. A startup claims it has cultivated functional sperm and used it to create embryos that appear healthy.
Paterna Biosciences, based in Utah, USA, says the approach could one day allow some men with specific forms of infertility to have biological children. The method starts by extracting sperm-producing stem cells from testicular tissue, then encouraging them in a lab dish to develop into fully formed sperm.
In the body, turning these stem cells into mature sperm takes a little over two months and happens in stages. The cells originate in the testicles’ tightly coiled tubules, then go through meiosis, a division process that leaves them with 23 chromosomes.
During this phase they also form the head and tail needed for movement. They then migrate to another area of the testicles, where they develop the ability to swim.
Finally, the vas deferens (one of the main tubes in the male reproductive system) carries the sperm and releases them into semen. Alexander Pastuszak, CEO and cofounder of Paterna, who is also a board-certified urologist and an associate professor of surgery at the University of Utah School of Medicine, said, as reported by WIRED: “There are very strict control mechanisms at every single one of those steps.
“We’ve figured out the instructions that are needed to teach these stem cells to become mature, normal sperm.” Paterna first tried growing the tiny tubes in the testicles where sperm normally develop, to see if they could make sperm in the lab.
But it didn’t work well, according to WIRED. Instead, the company reportedly focused only on the stem cells that go on to make sperm.
They kept these cells alive in a dish and encouraged them to turn into sperm. To do this, the team used computer-based research to work out which chemical “signals” the cells need at each stage.
They then tried different mixes of molecules until they found the right combination. Larry Lipshultz, a professor of urology at Baylor College of Medicine, who is not involved with Paterna, said: “This is huge.
“People didn’t understand, or had never figured out, what growth factors you have to supply to these cells to get them to become mature sperm. Apparently, they’ve identified these substances.”
Paterna thinks the male infertility problem is the “environment” around the cells, so it tries to copy a healthy one in the lab to produce lots of sperm from a small tissue sample. Early tests suggest the lab-made sperm look like normal sperm, but it’s not ready for pregnancies yet and bigger studies are planned.
Pastuszak said: “That will actually tell us a ton regarding the efficacy and safety of the approach. It will tell us if there are any mutations that are created by the in vitro process.”
Trials of lab-made sperm to start pregnancies could begin as soon as next year, WIRED reported. Medicines, IUI and IVF can help some men with low-quality or low-amount sperm, but men who make no sperm have far fewer options.
One option is surgery to search for sperm in testicular tissue, but it needs a general anaesthetic, can take up to four hours, and often still finds nothing. Paterna wants to replace this with a small testicle biopsy taken in a doctor’s office, then grow sperm in the lab, costing around £4,000-£9,500.
The approach might also help boys who have chemotherapy before puberty, as they already have sperm-forming stem cells, though returning frozen testicular tissue is still experimental and hasn’t led to any reported births, as per WIRED.
Other teams are trying to make sperm using “reprogrammed” cells, like skin or blood cells turned into stem cells that can become almost any cell type. In mice, scientists have already made working sperm and eggs this way and produced healthy babies, and in theory it could one day help same-sex couples by creating sperm or eggs from a skin sample.
A US fertility specialist says Paterna’s work is promising, but the high cost of fertility treatment could put it out of reach for many people.
Paterna’s results have not yet been published in a peer-reviewed journal or independently confirmed.
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