The goal, he says, is to create thousands of sperm from a standard tissue biopsy. The company has had a high success rate in generating sperm from dozens of tissue samples.

Pastuszak says early testing shows the lab-made sperm look “effectively identical” to naturally made sperm. The procedure is not yet ready to be used to start pregnancies, though. Paterna created embryos as an early test to validate that its lab-made sperm was actually viable. The company plans to conduct a larger, more comprehensive study involving men with infertility. Paterna will extract sperm from their ejaculate or testicular tissue and use its method to generate sperm for the men. From there, the company will use both the extracted sperm and lab-made sperm to fertilize eggs in the lab, compare fertilization rates between the two groups, and analyze the resulting embryos for physical and genetic 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 says. After that, trials of lab-made sperm to start pregnancies could begin as soon as next year.

Certain types of medication, intrauterine insemination, and conventional in vitro fertilization, or IVF, can help men with reduced sperm quantity or quality. But for men who make no sperm at all, treatment options are more limited.

“In terms of male infertility, the most challenging scenarios for clinicians are where men don’t have any sperm,” says Ryan Flannigan, a surgeon who specializes in sperm retrieval at the Vancouver Prostate Centre in Canada, who is not part of Paterna. “You see the emotional toll and the impact on these individuals and couples.”

For these men, a surgical procedure that looks for sperm in testicular tissue is an option. It requires general anesthesia and can take as long as four hours, depending on how quickly sperm are found. Even then, surgeons fail to find sperm in a significant percentage of cases.

Paterna’s technology is designed to replace that process, instead taking a small biopsy of testicular tissue in a doctor’s office. That tissue would be sent to Paterna, which would perform in vitro spermatogenesis. The company plans to charge somewhere between $5,000 and $12,000 for the procedure.

Flannigan says Paterna’s technique could also be used for boys who undergo chemotherapy for cancer treatment before puberty, since sperm-forming stem cells are present from birth. Young cancer patients have had the option of freezing and preserving testicular tissue for years, but transplanting it back remains experimental, and no births have been reported.

Other efforts to produce sperm in the lab are focusing on induced pluripotent stems, skin or blood cells that have been reprogrammed to an embryonic-like state. These stem cells can be coaxed into any type of cell in the body using the right set of instructions. Scientists have successfully produced functional sperm and eggs from mouse pluripotent stem cells and created healthy offspring. The technique, known as in vitro gametogenesis, could be used to help same-sex couples have biological children, since an egg or sperm could hypothetically be created from a skin sample.

Justin Dubin, a urologist and director of men’s sexual health at Baptist Health Miami Cancer Institute, says Paterna’s advance is exciting but cost will be a limiting factor for many patients in the US and other places where fertility treatments are prohibitively expensive.

“We’re coming up with so many amazing options in fertility care, and yet so many of them are not covered by insurance,” he says.

“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.”