12-week-old Grady, born from cryopreserved testicular tissue. Photo: Oregon Health and Science University
Scientists successfully froze immature testicular tissue and later transplanted it so it could mature and produce sperm that successfully led to a baby in primates — the first time a live birth resulted from a graft of this type of tissue, according to a study published in Science Thursday.
Why it matters: This research is a step towards the goal of allowing young male cancer patients to be able to reproduce later in life if they so choose. As cancer treatments improve, more than 80% of U.S. kids who get cancer now survive but 30% of those will have permanent infertility due to their treatments.
Background: While adult males can undergo successful cryopreservation of their sperm before their treatments start, prepubescent males' stem cells haven't yet gained the ability to turn into sperm.
- However, several centers around the world have started preserving testicular or ovarian tissues for children undergoing chemotherapy or radiation in anticipation that new therapies will be developed. This includes UPMC in Pittsburgh, which is the base of operations for study author Kyle Orwig.
- "... In our research laboratory, we are committed to responsibly [developing] the next generation of reproductive therapies that will allow our patients to use their tissues to produce eggs or sperm and have biological children," Orwig tells Axios.
What they did: Over a 2-year period, the research team removed and froze testicular tissue from 5 young rhesus macaques, and implanted the tissue back into the monkeys once they reached puberty.
- They also implanted a comparison set of fresh, unfrozen samples, and a few months later tested for sperm.
What they found: Both the fresh and frozen tissue had successfully and safely produced sperm.
- When the sperm from the frozen tissue were used to fertilize 138 eggs, 41% developed into embryos.
- The scientists transferred 11 embryos into female macaques and one became pregnant and had a baby monkey, named Grady.
"It was important to demonstrate that this would work with frozen and thawed tissues because young cancer patients may need to keep their tissues in cryo-storage for years or even decades before they return to use those tissues to have a child," Orwig says.
These results bring hope to young boys that they could later become fathers using their own sperm, says Susan Taymans, who oversees the funding provided by HHS' National Institute of Child Health and Human Development, which helped pay for this research.
- "This is an important quality of life issue. Surviving cancer is of course the primary concern, but having survived, patients naturally want a normal healthy life, which includes having the option to father a child," Taymans tells Axios.
- Monica Laronda, assistant professor of pediatrics at Northwestern University's School of Medicine who was not part of this study, says this work shows "promising results" and was an important step "for moving this research into the clinic."
Yes, but: More research is needed that more closely replicates the procedures humans undergo to see if it would work as well in people, and to determine if there's a risk of the transplant causing a recurrence of the cancer.
- "Not all cancers will have the same risk for this. ... Maybe in the future it will be possible to screen the tissue without harming it before re-implanting. There are some other conditions besides cancer that are treated with radiation and/or chemo, and those patients would not be at risk of reintroduction of disease when the tissue is grafted back in," Taymans points out.