Rest easy, world: Baby Grady is alive and well.
Grady is a rhesus macaque living out her days at the Oregon National Primate Research Center. But that’s not what makes her unusual. Rather, she’s the first primate ever born from sperm taken from testicular tissue grafted onto an adult monkey. This scientific breakthrough could lead to treatments that allow men who received fertility-compromising cancer treatments before puberty to father children in adulthood, according to a study published today in the journal Science.
Prior research has successfully performed this procedure in rodents and pigs, but “it’s a huge step that this can be performed in primates,” Ellen Goossens, a reproductive biologist at Vrije University Brussels who was not involved in the study, told Heidi Ledford at Nature. However, applying the technique to human populations is still a long way off, she adds. Before that happens, researchers will need to figure out how to ensure these sorts of tissue transplants don’t harbor any dormant, cancer-causing cells that could seed new tumors.
A cancer diagnosis during childhood can be devastating—and while many treatments like chemotherapy can be extremely effective at killing off cancerous cells, they often wipe out sperm and eggs in the process. Adult men undergoing chemotherapy can bank their sperm for later use, but prepubescent boys whose testicles are still developing don’t have this option.
One potential alternative for these young patients could be to harvest and freeze tissue from the testes themselves prior to chemotherapy, then sew it back in place after the cancer’s been dealt with. To explore this possibility, a team of scientists led by Kyle Orwig, a reproductive biologist at the University of Pittsburgh School of Medicine, tried the technique on five young rhesus macaques.
Less than a year later, the grafted tissue had matured to the point where it was producing both testosterone and sperm—clear indicators that they still had reproductive viability. Sperm was then extracted from one of the macaques to produce an embryo via in vitro fertilization. And just a few months later, Grady was born.
Grady (a portmanteau of “graft-derived” and “baby”) is now a healthy one-year-old. But scientists will be keeping an eye on her throughout the rest of what will hopefully be a long and uncomplicated life to ensure her developmental trajectory stays normal.
If things pan out, the next step could involve preliminary trials with human tissue. But in the meantime, there are still a couple of caveats to this procedure. For one, the technique at hand isn’t just a simple case of popping testes off and back onto the body. Once transplanted back onto its owner, the tissue takes hold—but the tubes that typically ferry sperm from testis to penis aren’t hooked back up. This means conception can’t happen through typical means: The only way to fertilize an egg is through assisted reproductive technology.
Another big concern is ensuring that there isn’t cancer lying in wait in the frozen testicular tissue. This probably wouldn’t be an issue for patients whose cancers haven’t spread to the testes. But for people suffering from testicular cancer, or cancers that can spread malignant cells throughout the body, like leukemia or lymphoma, grafting old tissue back into the body could put a cancer survivor back at square one.
The technique will also need refining, and isn’t yet efficient. Though the researchers fertilized 138 eggs with the sperm harvested from these transplants, the process yielded just 11 viable embryos—only one of which was carried successfully to term.
But even one live birth is extraordinary, Orwig says. “You can’t believe how proud I was,” he told Rachel Becker at The Verge. “We produced a baby in a way that nobody has ever produced a baby before.”