In a study recently published in Science, researchers have found a way to allow genetically infertile male mice to produce healthy offspring.
In males, addition of an extra chromosome can lead to infertility. The researchers were able to remove the extra sex chromosome in mice, a procedure that may someday allow men with Klinefleter syndrome (XXY) or Double Y syndrome (XYY) that are infertile to have children through assisted reproduction.
The concept came about when it was noted that fibroblasts extracted from XXY and XYY mice and induced to become stem cells sometimes lost the extra sex chromosome. From there, the researchers guided the stem cells to develop into mature sperm cells, which were then injected into the testes of a host mouse. Finally, the mature sperm was harvested and used to create healthy, fertile offspring through assisted reproduction.
The authors speculate this may someday allow males with three sex chromosomes to reproduce and could have applications for other complications related to having three chromosomes, but they acknowledge that this research is still in its very early stages. "There is currently no way to make mature sperm outside of the body. In our mouse experiments we have to inject cells that have the potential to become sperm back into the testes to help them finish developing. But we found that this caused tumors in some of the mouse recipients. So reducing the risk of tumor formation or discovering a way to produce mature sperm in a test tube will have to be developed before we can even consider this in humans," senior author James Turner, Group Leader at the Francis Crick Institute, explains.
Image: Illustration of the research set-up. Image courtesy of Takayuki Hirota.