Ordinarily, when germ stem cells divide into two cells, one "daughter" cell differentiates to become a sperm while the other remains a stem cell. Until recently, researchers had been unable to keep such germ-line stem cells from differentiating for extended periods of time. In contrast, embryonic stem cells from mice and humans have been kept from differentiating indefinitely.
A research team in Pennsylvania recently reported similar results with rat sperm to those of the UT Southwestern work; however the UT Southwestern team used substantially different techniques for sorting, growing and maintaining their stem cells in culture.
Armed with a long-lived, renewable source of rat sperm stem cells, researchers at UT Southwestern are now working to genetically manipulate those cells. For example, the scientists want to delete specific genes from the sperm stem cells and transplant the cells back into male rats, with the goal of producing "knockout," or genetically altered, animals to study health and behavioral effects related to those missing genes. Knockout mice are often used in research, but they are produced using a different method than the new sperm-cell approach.
"It will be quite valuable to bring this to the rat because it would enable us to generate knockout rats to do genetic studies," said Dr. Kent Hamra, assistant professor of pharmacology at UT Southwestern and lead author of the PNAS study. "It is a larger animal, it's often better for toxicology and physiology studies, and its behavior is more in tune with that of humans in many cases. It's also important to be able to produce pluripotent rat cells, because we would then have another animal model to test stem cell-based therapies, such as correcting diabetes."
One of the next steps is to determine whether human male germ-li
Source:UT Southwestern Medical Center