Oct. 22 (UPI) -- Researchers have figured out how to grow human stem cells to help children treated for cancer who become infertile later in life.
Healthy sperm cells before chemotherapy were grown and preserved in a study of mice. The findings were published Monday in the journal Nature Communications.
"For years researchers have been trying to find ways to grow and expand these cells from testicular biopsies donated by young patients prior to their cancer treatment, but until now, there has not been a consistently successful approach," study co-author Dr. Sandra Ryeom, an associate professor of cancer biology in the Perelman School of Medicine at the University of Pennsylvania and co-leader of the Tumor Biology Program at the Abramson Cancer Center, said in a press release.
About 1 in 530 men between the ages of 20 and 39 survived childhood cancer, according to the American Cancer Society.
But cancer treatments, including chemotherapy and radiation, leave most boys infertile because sperm-producing stem cells are killed.
There are ways to keep boys diagnosed with cancer fertile after puberty, but no options exist for prepubescent boys.
"We have never had any fertility preservation options for prepubescent boys," said study co-author Dr. Jill Ginsberg, a pediatric oncologist and director of the Cancer Survivorship Program at Children's Hospital of Philadelphia. "The findings in this work are a great first step forward for our youngest patients."
In the past, researchers have restored sperm production in mice that were sterilized after treatment with the chemotherapeutic agent busulfan. This was done by injecting immature sperm cells from a donor into their seminiferous tubules in the testes.
Based on this knowledge, oncologists have suggested that the cells might be harvested from boys before the start of chemotherapy and reintroduced into their testes when treatment was complete.
But because these prepubescent boys' testes contain such a small number of cells, they would need to multiply in the lab before reinjection.
The researchers identified that testicular endothelial cells were a critical niche population for the maintenance and expansion of human cells in the lab. They also identified five growth factors produced by testicular endothelial cells to keep human and mouse cells cultures alive for a long time. They envision freezing them until needed.
In the study, mouse cells in long-term culture restored the ability of mice after chemotherapy-induced infertility to produce sperm. In fact, they fathered live mice with the transplanted cells.
"Our next step is to determine whether we can reinject or engraft the expanded SSCs into patients after they are cancer-free," Ryeom said.