Veterinarian, National Medal of Science winner leads research on human male fertility

PHILADELPHIA — Veterinarian Ralph Brinster, who recently became the first veterinarian to earn the National Medal of Science, has published a new 14-year study that could reveal the keys to increased male fertility after treatment of childhood cancer. Although childhood cancer treatments typically have a success rate of around 80 percent, boys who receive the treatment can be left sterile as adults.

Brinster, the Richard King Mellon Professor of Reproductive Physiology at the University of Pennsylvania School of Veterinary Medicine (Penn Vet), completed the study with the help of the Department of Animal Biology at Penn Vet, the Department of Cell and Developmental Biology and Penn's Perelman School of Medicine and the Penn Bioinformatics Core.

In the study Brinster surmised that if a sample of spermatogonial stem cells could be extracted and preserved before cancer treatment and reimplanted after the male reached adulthood, this fertility problem could be circumvented.

Brinster used cells frozen for long periods of time that he had on hand, mostly from mice, to test long-term cryopreservation of spermatogonial stem cells, and he found his techniques to be successful.

"Human and animal spermatagonial stem cells have been successfully frozen for short periods of time, but this is completely different," Brinster explains. "Here we had cells frozen for over a decade that implanted in the right place and made sperm, and that sperm made offspring without apparent genetic defects."

The research was supported by the National Institutes of Child Health and Human Development, the Institute of General Medicine and the Robert J. Kleberg Jr. and Helen C. Kleberg Foundation. The full study can be found in the journal Human Reproduction.