Man produces sperm from testicular tissue frozen as a child in breakthrough trial

In a groundbreaking fertility trial, a man whose testicular tissue was frozen before he underwent chemotherapy as a child to be re-transplanted 16 years later has been able to produce sperm.

It is the first time a transplant of cryopreserved prepubertal testicular tissue has been demonstrated to restore sperm production in an adult patient. The 27-year-old man had the sample frozen when he was 10, before undergoing potent chemotherapy as part of treatment for sickle cell disease.

“This is a huge finding,” said Prof Ellen Goossens, of the Vrije Universiteit Brussel, who led the trial. “Many more people will have hope that they can have biological children. It’s great to see for the patients for whom we already have tissue banked.”

Treatments such as chemotherapy and radiotherapy can be life-saving for childhood cancer and sickle cell patients – but can also leave them infertile. After puberty, it is possible to preserve male patients’ sperm to use later in IVF, but this is not an option for prepubescent boys.

In 2002, the Belgian clinic became the first to start banking testicular tissue of prepubertal patients. The immature testes contain spermatogonial stem cells – the precursors of sperm – and sertoli cells, essential “nurse” cells that support and nourish developing sperm.

“At that time this field was in its infancy,” said Goossens. “These methods were just being developed in animals. We told patients’ families we couldn’t guarantee that the fertility restoration would be successful.”

The clinic’s first wave of patients are now reaching their mid-20s and some have reached the point of wanting to start a family, including the first patient to have tissue re-transplanted. To treat his sickle cell disease, he had received high-dose chemotherapy in 2008 to wipe out his own blood cells before undergoing a bone marrow transplant. Before the treatment, the clinic surgically removed one testicle, segmented it into small pieces and froze the tissue.

Last year, four tissue fragments were grafted back into the remaining testicle and four under the skin of the scrotum. After a year inside the body, the grafts were removed and analysed in the laboratory. The results are published in a preprint paper, which is yet to be peer reviewed.

Two of the grafts from inside the testicle had produced mature sperm, which was collected and frozen. Because the tissue fragments are not directly connected to the sperm duct, the researchers do not expect sperm cells to naturally find their way into the semen.