While medical professionals have successfully transplanted organs like hearts, lungs, and corneas, successfully transplanting testicular tissue has remained a challenge—until now. This breakthrough paves the way for innovative treatments for male infertility.
In a preprint paper released online earlier this year, which is yet to be peer-reviewed, Belgian doctors shared their success in reimplanting testicular tissue into a male patient with sickle cell disease—an ailment that can lead to infertility—many years after the tissue was initially removed.
This groundbreaking transplant has been decades in development. Starting in 2002, the Belgian team began preserving testicular tissue from young patients undergoing treatments with a high risk of causing sterility. Their method involved removing one testicle, cutting it into small fragments, and freezing them. According to Herman Tournaye, co-author of the study and an obstetrician-gynecologist at Vrije University of Brussels, the only method to restore fertility was to use cells from the same individual who would later receive the transplant.
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“Transplanting testicular tissue from another person wouldn’t be effective,” says Tournaye. “If I were to graft my testicular tissue into your testis, it would be rejected. It might survive with some immunotherapy, but the concept here is to take testicular tissue from a boy and graft it back into the same individual to avoid rejection.”
After initially freezing the testicular tissue, researchers spent years refining their techniques using animal models. The patient, who had his tissue frozen in 2008, later approached the team, expressing his desire to have children with his girlfriend.
In December 2024, during the procedure, doctors thawed 11 tissue fragments and grafted them into eight locations within the patient’s scrotum. A year after the operation, they retrieved the grafts and discovered the production of sperm cells had begun.
The journey of testicular transplantation dates back to at least 1913, when American doctor Victor Lespinasse attempted the procedure, grafting thinly sliced testicles from cadavers into recipients as a treatment for impotence. There are also instances of successfully reattaching a traumatically amputated testicle, with sperm production resuming in some cases.
Although scientists have achieved sperm production from transplanted testicular tissue in animals before the 21st century, and have even witnessed mice undergoing the procedure produce offspring, this achievement marks the first successful attempt in humans.
Emilie Johnson, an associate professor of Urology at Northwestern University who was not involved in the study, described the results as “cautiously optimistic.”
“They observed spermatogenesis, which was remarkable, but they obtained only a few sperm,” she notes. “Moreover, the sperm morphology was not entirely normal,” potentially affecting fertilization success.
Another limitation of the procedure is that the grafts were placed in tissue not connected to the usual pathways for ejaculation. Consequently, for the recipient to father children, sperm must be collected via biopsy and implanted into his partner using in vitro fertilization, according to Tournaye.
“That’s his only option because there is no natural connection,” Tournaye states.
While this may seem like a complex and costly method of reproduction, Johnson points out that, in comparison to other procedures cancer patients undergo, it is “relatively minor.”
Compared with other fertility treatments, she adds, “this is relatively small.”
The patient was chosen because his condition, unlike cancers such as leukemia, did not pose the risk of reintroducing malignant cells during the transplant that could cause a recurrence. However, Tournaye suggests the procedure might be applicable to cancer survivors in the future.
“We have several techniques to examine small frozen tissue samples to determine if, in leukemia cases, such cells are present,” he notes.
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