Sperm Stem Cells Grown in Lab (cont.)
By manipulating the culture media that contains the spermatogonial stem cells, researchers might also be able to induce the spermatogonial cells to develop into sperm cells that could be used to fertilize eggs, providing a method to treat some types of infertility.
"This finding is likely to be applicable to humans," Dr. Brinster said. He added that the same growth factors needed to culture the mouse stem cells would likely foster the growth of human spermatogonial cells as well as the cells of other mammals.
Currently, males who undergo chemotherapy that renders them infertile can store their semen so that it can be used at a later date, should they wish to father children. However, this approach results in a less than 50 percent success rate. Boys who are too young to provide a semen sample but who also need such chemotherapy treatments could also be helped by the new technique. Their spermatogonial stem cells could be cultured to increase their numbers, frozen, and reimplanted at a later date, restoring their fertility.
Moreover, the new culture technique would allow researchers to further investigate the potential of spermatogonial stem cells as a source for more versatile adult stem cells to replace diseased or injured tissue. The replacement tissue might be used to help patients with spinal cord injury, or disorders like Parkinson's disease or heart disease.
To conduct their study, Dr. Kubota and his colleagues began with mice that had been genetically altered to express green fluorescent protein, or GFP, which gives off a green light in the presence of a certain wavelength of light. During key stages of the experiment, tissue from the donor mice gave off a green light.
At the first step, the researchers could distinguish spermatogonial stem cells from the cells used to nurture them in lab cultures by the green light the spermatogonial stem cells gave off. (A photograph of the spermatogonial stem cells appears at (http://www.nichd.nih.gov/new/releases/stem_cell.cfm.)
The spermatogonial stem cells also gave off green light when they grew and reproduced in the testes of the recipient mice. Similarly, about half of the baby mice fathered by the recipient mice also glowed green (See photo at http://www.nichd.nih.gov/new/releases/green_brown_mice.cfm.)
Additional funding for this research was provided by the Commonwealth and General Assembly of Pennsylvania, and the Robert J. Kleberg, Jr. and the Helen C. Kleberg Foundation.
Source: National Institutes of Health press release, Wednesday, November 3, 2004
Last Editorial Review: 11/4/2004