The rate of survival for childhood cancers has increased dramatically in the last several decades, but a serious side effect of treatment is diminished fertility later in life. A potential treatment for boys facing cancer treatment would be to harvest, freeze, and, after the cancer is cured, re-implant their testicular tissue, which contains stem cells that could give rise to sperm.
What happens to that tissue, however, when subjected to the long-term freezing that could be necessary, has remained unclear. A new study in rats by University of Pennsylvania researchers has shown that male testis tissue that is cryopreserved can be re-implanted after more than 20 years and will go on to make viable sperm. The work, led by senior research investigator Eoin C. Whelan, was published in PLOS Biology.
While the long-frozen testicular tissue could produce sperm, the team found that the long delay did come with a cost in reduced sperm production compared to tissue that is only briefly frozen. The results may have important implications for treatment of prepubertal boys with cancer, for whom chemotherapy may be preceded by harvesting and freezing of testicular tissue for eventual re-implantation.
“The glass-half-empty way of looking at this is that stem cells do seem to be compromised in their ability to regenerate sperm after a long freezing time,” Whelan says. “But the good news is that sperm can be produced, and they seem to be transcriptionally normal when we examined their RNA.”
The findings underscore that sperm can be produced from long-preserved testicular tissue. Further research to potentially identify and mitigate the key drivers of viability loss could improve the reproductive options of boys whose childhood cancers are successfully treated.