A clinic in Belgium has been given the go-ahead to reimplant frozen testicular tissue to obtain sperm for fertility treatments. The hope is that the procedure will allow those whose fertility was destroyed by cancer treatments before they reached puberty to have children.
鈥淥ur protocol has been approved by the ethical committee, and now we are waiting for the first case,鈥� says at the Free University in Brussels (VUB).听鈥淚t can be expected in the near future.鈥�
Cancer treatments such as chemotherapy or radiotherapy can sometimes make people infertile. In those old enough to produce sperm, samples can simply be frozen for later use for IVF. For prepubescent children who don鈥檛 produce sperm yet, this isn鈥檛 an option, but their testes do contain spermatogonial stem cells, the cells that later produce sperm. These can be preserved by removing small pieces of the testes and freezing them.
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After animal studies suggested that it might be possible to derive mature sperm from spermatogonial stem cells, Goossens鈥檚 group began offering so-called testicular tissue banking in 2002. A growing number of centres worldwide are following suit, and a survey in 2019 found that testes tissue had been collected from .
A breakthrough in the animal studies came recently, says at the University of Edinburgh in the UK, who wasn鈥檛 involved in the work.听A team in the US froze testicular tissue from rhesus macaques and later reimplanted it in the scrotum or under the skin of the back. All the grafts began producing testosterone and mature sperm, which were extracted and used to fertilise eggs. In 2019, the team reported that听the process resulted in听.
鈥淭his is proof of principle in the primate that the whole process from obtaining tissue, storing tissue, generating sperm and being able to generate offspring with those sperm is feasible,鈥� says Mitchell.
On the basis of these results, several centres have begun preparing to try reimplanting testicular tissue听 into the individuals from whom it was taken. Goossens鈥檚 group is likely to be the first.
鈥淪ince we were the first worldwide to offer testicular tissue banking to prepubescent boys, we now have the oldest cohort, including patients in their mid-twenties,鈥� she says. Some of these people may now be wanting to start a family and finding that natural conception isn鈥檛 possible, says Goossens.
These first attempts will be done as part of a clinical trial, says Mitchell. It may be several years before the procedure is tried in other countries.
In the UK, testicular tissue banking began only in 2015, so most individuals who have had tissues frozen are not yet 18. But this service is now being offered to anyone in the UK who might need it, he says. 鈥淲e have now done this for more than 350 patients.鈥�
Researchers are also exploring other ways of generating sperm from the frozen tissue. One is to try to grow the spermatogonial stem cells in the lab and generate sperm without reimplanting the tissue into the body. On 19 October, a team in the US reported that they had with sperm generated from stem cells.
Another possibility is reimplanting the stem cells into the tubes of the testes in a way that allows normal sperm production to begin, meaning couples could conceive without needing IVF. 鈥淭hat could generate natural fertility again,鈥� says Mitchell.
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