Manny Ita –
In a major medical first, researchers in Belgium have reported that a man who became infertile after childhood treatment has regained the ability to produce viable sperm using tissue preserved from his youth.
The procedure was carried out by specialists at University Hospital Brussels and Free University of Brussels (VUB). It involved transplanting frozen testicular tissue—taken from the patient when he was a child—back into his body years later.
The patient, who had sickle cell anemia, underwent chemotherapy as a child. Such treatments are known to damage fertility, often leading to azoospermia in adulthood. Before his treatment, one of his testicles was removed and preserved, a precaution aimed at possibly restoring fertility in the future.
Years later, after discovering he had no viable sperm, the man opted for the experimental transplant. In 2025, doctors grafted small pieces of the preserved tissue into his testicle and surrounding area.
A year after the surgery, some of those grafts began producing mature, mobile sperm. However, the sperm are not naturally reaching his semen, meaning he would likely need assisted reproductive techniques to father a child.
This case is part of an ongoing clinical trial NCT05414045 and has not yet undergone full peer review. Still, experts say the results are promising. The technique builds on the idea that even in pre-puberty, testicular tissue contains spermatogonial stem cells capable of later developing into sperm.
The concept of preserving such tissue dates back to 2002, when the Brussels hospital first began freezing immature testicular samples. Since then, more than 3,000 boys worldwide have had similar tissue stored as a precaution against future infertility.
While the breakthrough offers new hope, researchers caution that many questions remain. It is still unclear how long the transplanted tissue will function or whether the sperm produced can lead to healthy pregnancies.
Even so, the development marks a significant step forward in fertility preservation, particularly for boys undergoing life-saving treatments who previously had no options to safeguard their ability to have children later in life.
