In a world first, a medical team at University Hospital Brussels and the Free University of Brussels (VUB) has restored sperm production in a man left infertile by childhood chemotherapy.
The anonymous patient, now in his late 20s, was treated for sickle cell anemia as a 10-year-old in 2008. Before undergoing chemotherapy, his family consented to have one testicle removed and frozen. In 2022, he returned to Brussels IVF wanting to have a child but had no viable sperm in his remaining testicle.
As part of a clinical trial, surgeons reintroduced four grafts of his frozen testicular tissue back into his testicle and scrotum in 2025. Now, a year later, some of those grafts are producing mature and motile sperm.
While the sperm have not yet reached his semen, the achievement is a major milestone. The patient will likely need in vitro fertilization to conceive.
"This is an important step in further scientific research to preserve the fertility of children with cancer or other blood diseases," said fertility specialist Veerle Vloeberghs at Brussels IVF.
The case study, published ahead of peer review in medRxiv, offers hope to millions of childhood cancer survivors. Researchers will monitor the patient closely as he pursues biological parenthood, tracking embryo development and long-term health outcomes in any resulting offspring.