Chemotherapy in boys can damage the testicles and make subsequent paternity impossible. The problem: until puberty, no sperm have formed, which could be removed and stored before treatment.

Researchers have come a long way with the idea of ​​possibly preserving the fertility of young cancer patients. It helped monkeys: For the first time researchers have taken testicular tissue from young male primates, frozen and the same rhesus monkeys after puberty again planted. After that sperm developed in the tissue, which led to the birth of a healthy monkey baby.

"Grady was born on April 16, 2018 with a weight of 471 grams," writes the team around Adetunji Fayomi of the University Hospital Pittsburgh in the journal "Science". However, it has done some effort to bear witness to the animal:

  • Overall, the researchers have frozen testicular tissue from five young male primates.
  • As a result, precursors to sperm developed in all monkeys.
  • With these, the scientists fertilized 138 oocytes, 39 of which grew at least to the two-cell stage.
  • Finally, the researchers implanted eleven embryos into six female rhesus monkeys.
  • A pregnancy was successful.

Oregon Health and Science Univer

Monkey Baby Grady at the age of eleven months

The study is a proof of concept, the researchers write. Above all, they cite the fact that they have removed and re-implanted significantly larger pieces of tissue than in earlier experiments. The pieces were 9 to 20 cubic millimeters instead of 0.5 to 1 cubic millimeter in size.

Application in humans will take years

Even independent experts see the work as a milestone, but point out that it may take years to check whether the technology works well in humans.

The method that is now being investigated is fundamentally applicable to humans, write Stefan Schlatt and Nina Neuhaus of the Center for Reproductive Medicine and Andrology of the University of Münster in a commentary on the study. But it still has to be clarified whether it is safe for the offspring, adds Artur Mayerhofer from the University of Munich.

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There are also hurdles independently. The rhesus monkeys in the trial had been castrated. It still has to be confirmed that the technology also works with uncastrated primates, the researchers write. In addition, the method is not suitable for all cancer patients. In boys with leukemia, lymphoma and testicular cancer there is a risk that the extracted tissue contains malignant cells.

One third of the treated boys remain infertile

Cancer and other diseases such as sickle cell anemia can often only be treated with chemo and radiation. This can damage sperm or its predecessor so severely in male patients that those affected become infertile.

Adults can have their sperm removed before treatment, freeze it and later have an egg cell artificially fertilized. In boys, this is not possible: Before puberty, before the body releases more of the sex hormone testosterone, the sperm are not mature. Due to cancer alone, about one thousand boys in Germany receive potentially harmful fertility therapy each year.

In general, more than 80 percent of children today survive cancer, about one third of them remain infertile, the researchers write about Fayomi.