At 11 years old, Jaiwen Hsu’s world changed when a routine injury led to a diagnosis of bone cancer. While chemotherapy offered a chance at survival, it also carried a devastating side effect—likely infertility. In a desperate search for options, his parents enrolled him in a pioneering fertility preservation study at the University of Pittsburgh Medical Center, where doctors froze his testicular stem cells in hopes of one day restoring his ability to have children.
Now, at 26, Hsu has become the first person in history to undergo a transplant of these sperm-producing stem cells, testing whether science can reverse the fertility loss that often comes with childhood cancer treatments.
“The science is so new, we’re just waiting to see what happens,” Hsu said. “Right now, we’re crossing our fingers and hoping for the best.”
His case is at the forefront of a growing medical challenge: as childhood cancer survival rates climb to 85%, approximately one-third of those survivors face infertility due to chemotherapy and radiation. While older teens and adults can preserve their fertility by banking sperm or eggs before treatment, prepubescent children don’t yet produce mature reproductive cells—leaving them with few options.
That’s where cutting-edge research comes in. Boys are born with specialized stem cells in their testes, which remain dormant until puberty, when testosterone triggers sperm production. Funded by the National Institutes of Health, reproductive scientist Dr. Kyle Orwig has been exploring how to extract and preserve these cells in young boys before cancer treatment, then reintroduce them later in life to restore fertility.
Since 2011, Orwig’s team has collected and frozen testicular tissue from roughly 1,000 prepubescent boys. But would those preserved cells still work years later? Animal studies provided hope: in 2019, Orwig’s team successfully used frozen testicular tissue from a young monkey to produce a healthy baby monkey via in-vitro fertilization (IVF).
Then, in 2023, the opportunity arose to take the research to the next level. Hsu, curious about the study he had joined as a child, reached out to Orwig’s team. Though he wasn’t yet planning for a family, he wanted to contribute to scientific progress. In November 2023, Orwig and his colleagues performed the first-ever reimplantation of thawed human testicular stem cells, using ultrasound guidance to precisely deliver the cells back into Hsu’s testes.
“It was a straightforward and safe procedure,” Orwig reported in a study released this week, though his findings have yet to undergo peer review.
Now comes the waiting game. Unlike in animals, where fertility success could be measured through assisted reproduction, it remains uncertain how to track whether Hsu’s transplant will ultimately restore sperm production. Still, researchers say the study is an important first step—and may encourage more families to consider fertility preservation for young cancer patients.
Belgian scientists are also testing similar techniques, recently implanting entire pieces of testicular tissue into a childhood cancer survivor. “Human trials are the only way we’ll truly know if this works,” said researcher Ellen Goossens of Vrije Universiteit Brussel. Meanwhile, similar experimental procedures are being explored for female childhood cancer survivors using ovarian tissue.
For Hsu, the outcome remains unknown, but he’s grateful for the chance to participate. “Even if this doesn’t work for me, it will help others in the future,” he said. “My parents made a decision years ago that gave me the chance to make this choice for myself today.”