Scientists have discovered a population of easily isolable stem cells with reprogrammable properties in the testes of adult male mice. If similar cells exist in humans, they might then provide a noncontroversial source of pluripotent cells for use in regenerative therapies.

Embryonic stem cells (ESCs) may be the key to curing various diseases, from diabetes to Parkinson's, because scientists can coax them to differentiate into any cell type. However, various religious groups contest their use because it is necessary to destroy embryos to obtain them. Indeed, laws in the United States strictly limit the use of federal funds in stem cell research.

In recent research, a group led by Gerd Hasenfuss of the Georg-August-University of Göttingen (Germany) found that mouse spermatogonial stem cells (SSCs), which normally become sperm cells, seem to act similarly to ESCs (Nature, published online 24 March, doi: 10.1038/nature04697). They isolated SSCs from the testes of transgenic mice and demonstrated the cells' ability to differentiate into various cell types in culture. Next, the German group tested the cells' behavior in vivo, with promising results. SSCs injected into mouse embryos contributed to development of various organs, including heart, brain, intestine, and lung. When injected into immunodeficient mice, the cells formed teratomas, much as ESCs do.

Kaomei Guan, first author on the paper, assured Lab Animal that men do have SSCs with self-renewal and differentiation potential, and said that “the ultimate goal is to make the technique work to reprogram [human] SSCs into ESC-like cells.”

The use of similar techniques in humans would allow the cell therapy to be done using cells derived from the patient's own body via biopsy, solving the immunological problems associated with the use of foreign cells.

Guan noted that men would clearly benefit from such a discovery but that there is still hope for women. Recent research in mice revealed that female germline stem cells exist after birth, but no one has yet developed a culture system to test the cells' potential. “The chances of finding ESC-like cells in women is high,” Guan told Lab Animal. The research team's next step is to isolate and reprogram female germline stem cells.