Sperm Stem Cells Were Used for the First Time in an Attempt to Restore FertilityNEWS | 29 March 2025Jaiwen Hsu was an active 11-year-old when he developed pain in his left knee that forced him to sit out a few soccer games. What his parents thought was a sports injury turned out to be osteosarcoma, a type of bone cancer.
He started chemotherapy, which doctors warned could result in infertility. Hsu hadn’t reached puberty yet, so sperm banking wasn’t an option. His parents enrolled him in a study that was collecting and storing immature testicular tissue, and the sperm-forming stem cells in them, from young patients with the goal of eventually giving them a way to have biological children.
Now 26, Hsu and his doctors are waiting to see if an experimental transplant of these cells, extracted from a tissue sample taken back in 2011, will be able to restart sperm production. The procedure has been successful in mice and monkeys, but researchers say Hsu was the first person to undergo it in November 2023. The technique is detailed in a new paper that has yet to be peer-reviewed.
“As an 11-year-old, I don’t think I could quite understand the severity of having a cancer diagnosis or comprehend the idea of starting a family down the road and how important that would be,” Hsu tells WIRED.
In the early stages of his cancer treatment, Hsu and his family traveled from their home in Maryland to UPMC Children’s Hospital in Pittsburgh, where doctors collected a piece of testicular tissue containing the precious sperm stem cells. These stem cells are present even before puberty. During puberty, rising testosterone levels signal to these cells to develop into sperm, a process known as spermatogenesis.
In November 2023, at age 24, Hsu was reunited with those cells. After undergoing anesthesia, he received an injection of them into one of his testes. The hope is that the cells engraft into the spaghetti-like tubules of the testis and develop into mature sperm.
“If it works, those stem cells should regenerate spermatogenesis,” says Kyle Orwig, a professor of obstetrics, gynecology, and reproductive sciences at the University of Pittsburgh School of Medicine and the senior author on the new study. Even if it kick-starts sperm production, it might not be enough to come out in the ejaculate. “If there are, there definitely would not be enough sperm to restore natural fertility,” Orwig says.
In animals, it’s possible to remove a larger piece of testicular tissue, which yields more stem cells and more sperm. But in children undergoing cancer treatment, it’s important to minimize harm—and recovery time—so only a small amount of tissue is taken. That results in a relatively small number of stem cells.
For that reason, Hsu will likely still need assistive reproductive technology if he wants to start a family. He’s not at that point yet, but he said he chose to undergo the procedure now, in his mid-twenties, because “it gives us a good time cushion to see if this works.”
In the future, surgeons would likely need to cut into his testis and extract any sperm that might be there, which would then be used to fertilize an egg in a laboratory. Until Hsu is ready to have a child, researchers probably won’t know if the procedure worked.Author: Steven Levy. Emily Mullin. Kate Knibbs. Sassafras Patterdale. Matt Reynolds. João Medeiros. Marta Musso. Maggie Chen. Source
