Startup Claims It Successfully Grew Human Sperm in a Dish For the First Time to Help Infertile Men

The wider field of in vitro gametogenesis could change how we make babies forever.

For all of human history, reproduction has relied on a simple biological formula. Sperm meets egg. They fuse, they divide, and nine months later, a baby arrives.

Now, scientists are taking control of that formula. The equation for making a human is not straightforward anymore. In a laboratory in Utah, a startup called Paterna Biosciences claims it has successfully grown functional human sperm in a dish. They have even used these engineered cells to create visibly healthy-looking embryos.

This breakthrough answers one of the oldest puzzles in reproductive biology. More immediately, it offers profound hope to the infertile men who produce absolutely no sperm and have almost no options for starting a biological family. Yet the implications run deeper. It fires the starting gun on a massive leap forward in in vitro gametogenesis — the science of creating sex cells entirely outside the body — pushing humanity toward a future where the traditional rules of parenthood no longer apply.

Mastering the Microenvironment

Normally, a man’s body needs a little over two months to forge mature sperm. The testes operate like a staggered biological assembly line. While one batch of sperm cells just begins the journey to maturity, millions of others are already finishing it. The factory never shuts down, churning out millions of ready-to-go cells every single day. This means men can ejaculate daily, though sperm counts may be lower with very high frequency.

Stem cells sit inside the tightly coiled tubules of the testicles. They divide, halve their chromosome count to a neat package of 23, and sprout the tails they need to swim. A complex system pushes them along until they are ready for release.

“There are very strict control mechanisms at every single one of those steps,” says Alexander Pastuszak to Wired, who first broke the story of this advance, although the findings haven’t yet been peer-reviewed or independently verified.

Pastuszak is the CEO and cofounder of Paterna, and a urologist at the University of Utah School of Medicine. His team bypassed the physical testicle altogether. Instead, they extracted sperm-making stem cells and placed them in a lab dish. They used computer models to calculate the exact chemical signals these cells needed to thrive.

“We’ve figured out the instructions that are needed to teach these stem cells to become mature, normal sperm,” Pastuszak tells Wired.

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This solves a massive reproduction problem. Roughly 50% of all infertility cases involve male factors. About 10% to 15% of infertile men lack sperm in their ejaculate entirely. They possess the necessary stem cells, but their biological microenvironment fails them.

The whole point behind Paterna’s technique is to recreate a healthy environment in the lab, then use the cultured mature sperm for fertilization.

“This is huge,” Larry Lipshultz, a professor of urology at Baylor College of Medicine, tells Wired. “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.”

Rewriting the Rules of Parenthood

If we can grow sperm from testicular stem cells, could we make embryos using entirely different parts of the body?

The answer is yes. Science is already pushing beyond the testicle to ordinary skin.

At the Oregon Health and Science University (OHSU), researchers recently created early-stage human embryos using human skin cells.

They took a donor egg, stripped out its genetic material, and inserted the nucleus from a skin cell. They then coaxed the egg into shedding half of its chromosomes. Finally, they fertilized it with sperm.

The team produced 82 functional eggs. A handful developed into early embryos, though none grew beyond six days. The success rate hovers around a meager 9%.

Yet, this is just the beginning, and it seems like just a matter of time before these sorts of methods become commonplace.

“We achieved something that was thought to be impossible,” Prof Shoukhrat Mitalipov, the director of OHSU’s centre for embryonic cell and gene therapy, tells the BBC.

“We have to perfect it,” Mitalipov added. “Eventually, I think that’s where the future will go because there are more and more patients that cannot have children.”

Beyond infertile couples, the same technology offers a genuine biological route for same-sex male couples to produce offspring that are genetically related to both male parents. For instance, one partner’s skin can be turned into an egg, and the other’s sperm to fertilize it. The same applies to same-sex female couples, too. Scientists could theoretically reprogram one woman’s skin cells into sperm, which would then be used to fertilize her partner’s naturally produced egg.

A Race Against the Biological Clock

The quest to conquer in vitro gametogenesis (IVG) is moving with astonishing speed.

Prof Katsuhiko Hayashi, a developmental geneticist at the University of Osaka, estimates his lab is merely seven years away from creating viable human sex cells. Because IVG builds sex cells entirely from scratch rather than just maturing existing ones, the biological hurdles are exponentially higher than what Paterna Biosciences reportedly achieved.

“I feel a bit of pressure. It feels like being in a race,” Hayashi tells The Guardian. “On the other hand, I always try to persuade myself to keep to a scientific sense of value.”

The demand for this technology is palpable.

“We get emails from [fertility] patients, maybe once a week,” Hayashi says. “Some people say, ‘I can come to Japan.’ So I feel the demand from people.”

Silicon Valley is also placing heavy bets on the field. Startups like Conception Biosciences aim to manufacture clinical-grade human eggs.

Matt Krisiloff, CEO of Conception, tells the Guardian that their lab-grown eggs “could be massive in the future”.

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“Just the aspect alone of pushing the fertility clock . . . to potentially allow women to have children at a much older age would be huge,” Krisiloff said.

He views the technology on a civilizational scale.

“Outside of social policy, in the long term this technology might be the best tool we have to reverse population decline dynamics due to its potential to significantly expand that family planning window,” Krisiloff added.

Skeptics once dismissed these timelines. Now, their expectations require some serious readjustment.

“People might not realise how quickly the science is moving,” said Professor Rod Mitchell, a male fertility expert at the University of Edinburgh.

Safety, Costs, and Ethical Frontiers

Before clinical trials can begin, scientists must ensure the in vitro process does not introduce dangerous genetic mutations in the babies.

Paterna is planning rigorous testing. They will compare embryos made from natural sperm against those made from their lab-grown sperm to check for abnormalities.

“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,” Pastuszak tells Wired.

“We need to be confident that it’s safe before we could ever use those cells to make a baby,” Mitchell said.

Hayashi agrees entirely. “We really need to prove that this kind of technology is safe,” he tells The Guardian. “This is a big obligation.”

Even if proven safe, access remains a severe hurdle. Paterna aims to charge between $5,000 and $12,000 for their procedure.

Justin Dubin, a urologist at Baptist Health Miami Cancer Institute, worries about the financial barrier for everyday patients.

“We’re coming up with so many amazing options in fertility care, and yet so many of them are not covered by insurance,” Dubin tells Wired. “It’s a huge disservice to our patients, to the world’s population, by not providing people with the means to achieve the family that they want.”

Beyond money, profound moral questions linger. Could we eventually see unibabies created from a single person’s cells, or multiplex babies with DNA from three or more parents?

“Would anyone want to try these two options?” Prof Hank Greely of Stanford University wonders. “I don’t see why but it’s a big world with lots of crazy people in it, some of whom are rich.”

Hayashi, who famously engineered a living mouse with two biological fathers, remains cautious about pushing biology too far.

“Of course, although I made a [mouse] baby from two dads, that is actually not natural,” Hayashi said. “So I would say that the if the science brings outcomes that are not natural, we should be very, very careful.”