Birth of monkey could help ensure boys with cancer can have families
Testicular tissue taken from young monkeys, which is then frozen and grafted back into their bodies later in their life, can give rise to sperm and allow them to father live young, scientists have revealed.
While the approach has previously been successful in other animals, including mice, it is the first time a primate has produced offspring from the procedure. The team report the baby rhesus macaque that was born is a healthy female that has been named Grady, after “graft-derived” and “baby”.
The development has been hailed as a major breakthrough that could have profound implications for young boys with cancer.
Medical treatments such as chemotherapy and radiation can damage stem cells in the testes, affecting the production of sperm. While men can have their sperm stored before undergoing such treatments, boys who have not gone through puberty do not yet produce sperm.
“This advance is an important step toward offering young cancer patients around the world a chance at having a family in the future,” said Prof Kyle Orwig, co-author of the study from the University of Pittsburgh School of Medicine.
Writing in the journal Science, Orwig and colleagues reveal how they removed the testes from five rhesus macaques in two stages. One was removed before the animals entered puberty, with the tissue cut into small pieces and frozen. The other was removed five to seven months later as they approached puberty, with the tissue also cut up.
Hours later both this fresh tissue, and the tissue taken months before, was reimplanted into the monkeys, with three of each type of tissue placed under the skin on the animals’ backs and one of each type grafted under the skin of their scrotum.
Months later, both types of tissues were found to have grown and were producing sperm.
From one monkey the team took sperm produced after implanting previously frozen tissue under the skin of its scrotum. This sperm was then used to fertilise eggs from female rhesus monkeys. Of the 138 eggs used, 16 embryos were produced. Of the 11 embryos implanted into female macaques, one baby was born by caesarean section: Grady.
Experts were quick to welcome the news, pointing out that there was an urgent need for ways to preserve the fertility of young boys having cancer treatment.
“At present, we are only able to preserve male fertility by freezing sperm, and therefore this isn’t an option for boys younger than about 13 years old because they have not yet gone through puberty and started making any,” said Allan Pacey, a professor of andrology at the University of Sheffield.
Pacey and others have said it will be some time before such an approach is available to young patients, with further research needed to show it works in humans and is safe.
The team behind the latest research stress that in humans, the testes would not be removed, so further work is needed to be sure the approach would work. They add it might not be suitable for patients where there is a risk the tissue removed could contain cancerous cells.
Daniel Brison, a professor of clinical embryology at the University of Manchester, said the study was an important proof of concept, but that questions remain.
“The study is limited by the fact that only one animal was born, and more extensive pre-clinical studies are now required to address the long-term health of individuals conceived by this method,” he said.
