World medical news: UZ Brussel successfully transplants frozen testicular tissue after 16 years
UZ Brussel has a (second) world first to its name. Sixteen years ago, a 10-year-old cancer patient had preventive surgery to remove a testicle, which was then frozen in the hope of later restoring his fertility. Now the testicular tissue has been successfully replaced.

Those who get cancer as children and have to undergo chemotherapy risk being infertile as adults. In 2002, the Vrije Universiteit Brussel (VUB) and Brussels IVF, the centre for reproductive medicine at UZ Brussel, achieved a world first by becoming the first institution to successfully freeze and store testicular tissue. In this process, the testicular stem cells, from which sperm cells develop from puberty onward, are stored in cryotanks at -196°C in nitrogen gas.
Nearly a quarter-century later, UZ Brussel can add a second world first to its name. It has now transplanted the preserved testicular tissue into a now 26-year-old man. That task is already regarded as a success. Whether the stem cells actually produce mature sperm cells and the patient's fertility is restored will be seen in a year's time. The cells may not end up in the sperm sample naturally because the reinserted testicular tissue is not directly connected to the vas deferens. In this case, they will have to be refrozen and later injected into an egg.
But given successful trials with similar tissue in rhesus monkeys, there is good reason to hope that it will also succeed in humans.