Frozen testicular tissue transplanted in bid to restore fertility after chemotherapy
Protecting fertility is a major challenge for young men undergoing aggressive treatments such as chemotherapy. Freezing their own testicular tissue before such treatments could help.
A young patient in Edinburgh has undergone a pioneering procedure, receiving a transplant of his own testicular tissue, frozen before he began chemotherapy, in a development that could pave the way for male fertility preservation, a first such procedure in the UK and second worldwide.
“This is a big step towards helping boys facing treatments that damage their fertility to have children of their own,” said Rod Mitchell, professor of developmental endocrinology at the University of Edinburgh’s Institute for Regeneration and Repair.
The 19-year-old received a bone marrow transplant in 2023 to treat a serious blood disorder. Before starting treatment, he had testicular tissue removed and frozen because the high-dose chemotherapy could permanently damage the cells needed to produce sperm.
Three years later, tests showed that the patient had no sperm in his semen. In August 2026, doctors implanted some of his previously frozen testicular tissue back into his body in the hope that it would begin to produce sperm, the University of Edinburgh said in a press release.
“Fertility is something I’ve struggled with personally for a long time. I’ve always wanted to have children of my own but at some point, I found myself starting to slowly accept that that might never be possible for me,” the patient said after the transplant. “Having this procedure has given me genuine hope for the future.”
In the next eight months, doctors will remove and examine some of the transplanted tissue to determine whether sperm have been produced.
Why freezing tissue
Protecting fertility is a major challenge for young men undergoing aggressive treatments such as chemotherapy.
Semen freezing is an established option for adolescents and young men. It is not available to prepubertal boys, however, because they do not yet produce semen, leaving them with no means of preserving their fertility.
Storing testicular tissue could offer an alternative. It contains spermatogonial stem cells, which produce sperm from puberty onwards. Doctors hope that tissue frozen before treatment can later be returned to the patient and allow sperm production.
The Edinburgh testicular project was established in 2015 with the support of Children with Cancer UK. Since then, more than 1,200 patients in the United Kingdom and more than 3,100 worldwide have now had testicular tissue stored for potential future clinical use.
“We are beginning to see some of these young men return to explore their fertility options. This study offers real hope for future fertility in boys facing cancer treatment,” Mitchell added.
Experimental phases
The trial procedure in Edinburgh is the first of its kind in the UK and only the second reported worldwide.
The first reported transplant of frozen testicular tissue took place in Belgium in January 2025. In that case, the cryopreserved tissue was reintroduced into an infertile man who had undergone chemotherapy in childhood, after 16 years in storage.
The researchers wrote in the preliminary results of the study that dormant stem cells within the transplanted tissue revived and began producing sperm cells, a process known as spermatogenesis.
When researchers evaluated the tissue a year after surgery, they confirmed that the sperm cells had developed fully.
