In what scientists are calling a "huge finding" (and what everyone else is calling "about time"), a 27-year-old man has produced sperm from testicular tissue that was frozen when he was a child - 16 years after it was removed. The Belgian man had the tissue cryopreserved at age 10 in 2008, before undergoing high-dose chemotherapy to treat sickle cell disease, a treatment that typically wipes out fertility along with the bad blood cells.
Prof Ellen Goossens of the Vrije Universiteit Brussel, who led the trial, said: "This is a huge finding. Many more people will have hope that they can have biological children." The clinic first started banking testicular tissue from prepubescent patients back in 2002, when the field was - as Goossens put it - "in its infancy." At the time, they told families they couldn't guarantee the frozen tissue would ever work. Turns out, patience and a freezer can accomplish a lot.
Chemotherapy and radiotherapy save lives but often leave childhood cancer and sickle cell patients infertile. After puberty, doctors can collect sperm for IVF, but prepubescent boys don't have that option - their testes contain spermatogonial stem cells (sperm precursors) and Sertoli cells that act as "nurse" cells, but no actual sperm yet.
Last year, four tissue fragments were grafted back into the man's remaining testicle and four under the skin of his scrotum. After a year, two grafts from inside the testicle produced mature sperm, which were collected and frozen. Because the tissue fragments aren't connected to the sperm duct, the sperm won't naturally appear in semen - so the researchers will need to extract them directly. The results appear in a preprint paper that has not yet been peer reviewed.
"The sperm that was isolated looked normal," Goossens said. "We still have to see whether it's able to fertilise an egg."
Prof Rod Mitchell, who runs a similar trial at the University of Edinburgh's Centre for Reproductive Health, called it "proof of principle in humans" and said his clinic expects to carry out the first transplants "imminently." The Edinburgh team began banking tissue in 2014 and, along with colleagues in Oxford and London, have samples for more than 1,000 UK patients. Worldwide, more than 3,000 patients have testicular tissue banked, and about 200 UK patients per year could benefit.
"I always believed it would work," Mitchell said. "If you freeze tissue and keep cells alive, then they should have the potential. You're putting the tissue back into the perfect environment to stimulate it. Scientifically and biologically it makes sense. In reality, it's still amazing."
The first patient is now deciding whether to undergo another round of grafts to collect more sperm or proceed with IVF. Either way, the frozen tissue gamble - 16 years in the making - has finally paid off.