Sperm Stem Cells Grown in Lab
November 4, 2004 -- Researchers have succeeded in growing sperm stem cells in laboratory cultures. These cells were then transferred to infertile mice who produced sperm and fathered baby mice. Each baby mouse was genetically related to the sperm stem cell donor, not to the mouse producing the sperm.
Actually, this research team has been working on similar technology for over ten years. What is new is that specific genes can be inserted into the sperm stem cells which can then be grown in culture to provide an endless supply of these cells.
The researchers point out that their technology developed in mice could also be used to treat infertility in humans. Sperm stem cells could be removed from a donor, cultured to increase their numbers, frozen, and then reimplanted back into the donor (or another male) at a future date.
The researchers also propose that these sperm stem cells have the "potential" of serving as a source for more versatile adult stem cells to replace diseased or injured tissue. Because of the current controversy swirling around the development of stem cell lines, this application requires a much bigger leap of faith.
Researchers Grow Sperm Stem Cells in Laboratory Cultures
A team of researchers working with cells from mice has overcome a technical barrier and succeeded in growing sperm progenitor cells in laboratory culture. The researchers transplanted the cells into infertile mice, which were then able to produce sperm and father offspring that were genetically related to the donor mice.
"This advance opens up an exciting range of possibilities for future research, from developing new treatments for male infertility to enhancing the survival of endangered species," said Duane Alexander, M.D., Director of the NICHD.
Their research, funded in part by the National Institute of Child Health and Human Development of the National Institutes of Health, will be published online this week in an upcoming issue of Proceedings of the National Academy of Sciences.
Led by Hiroshi Kubota, D.V.M., Ph.D., the team of researchers from the University of Pennsylvania School of Veterinary Medicine in Philadelphia, also included Mary Avarbock and Ralph L. Brinster V.M.D., Ph.D. The researchers succeeded in developing the culture medium containing the precise combination of cellular growth factors needed for the cells to reproduce themselves outside the body. Known as spermatogonial stem cells, the cells are incapable of fertilizing egg cells but give rise to cells that develop into sperm.
In 1994, this same research team developed the means to transplant spermatogonial stem cells from one mouse into another. The recipient mice then produced sperm - fully capable of fertilizing egg cells - with the genetic characteristics of the donor mice.
Because they can now grow spermatogonial stem cells in culture, researchers have a ready source of cells that they could manipulate genetically, explained the study's senior author, Ralph Brinster.
For example, researchers could implant a new gene into a spermatogonial cell, reproduce a large number of spermatogonial cells in the culture medium, and then implant the cells into recipient animals. These animals could then pass the new trait on to their offspring. The ability to introduce a new trait into animals would greatly assist breeders of both livestock and laboratory animals.
Moreover, by culturing and freezing spermatogonial stem cells from a valuable livestock animal or an endangered species, researchers could extend the reproductive life of that animal indefinitely. (The researchers developed a technique for successfully freezing and thawing spermatogonial cells in 1996.)