In macaque monkeys, researchers at the University of Pittsburgh and colleagues successfully used stem cells to reverse sterility caused by cancer treatments, and the team used sperm from one of the treated animals to successfully fertilize a number of eggs. The hope is to eventually use the same treatment in young boys made infertile by chemotherapy, though the treatment itself carries cancer risks.
"This demonstrates in an animal model that in fact it's feasible," principal researcher Kyle Orwig told The Canadian Press. (He directs the University of Pittsburgh's fertility preservation program.)
Details of the work are published in the November issue of the journal Cell Stem Cell. As The Canadian Press reports, scientists pursued their experiment with small pieces of testicular tissue that had been frozen and then were thawed and placed back in the monkeys after chemotherapy treatments. The tissue, which contained spermatogonial cells, began producing sperm in most of the animals, the story notes.
This is something that researchers have long hoped to accomplish in people. A number of clinics globally have frozen human testicular tissue from boys treated for cancer who haven't hit puberty yet, the story notes, with the idea that they can someday be used for subsequent male fertility treatments. Not every male child treated for cancer becomes infertile but the risk is high, according to the article, because the drugs can destroy stem cells in the testes that enable sperm production once puberty hits.
That alone gives reason to be hopeful about this study. But a number of disclaimers are in order. First, the promising results from testing in monkeys aren't necessarily repeatable in humans, and many more preclinical tests on safety and efficacy will be needed before we even get to that point. And then there is the risk involved. The researchers stress that there's a lack of consensus about when frozen testicular cells should be re-implanted. Performed too soon, the stem cell procedure could bring cancer cells back into a testicle, they explain.
Preclinical studies will help sort that issue out, though the initial finding does give hope that boys treated for childhood cancer who face sterility can have a family some years down the line.