Skin cells taken from men diagnosed as infertile can be modified into stem cells to create a precursor to sperm. The new research suggests a possible line of treatment that may finally yield a treatment for male infertility, researchers say.

Scientists at Stanford University removed skin cells from some men with azoospermia, a genetic syndrome that makes it impossible for them to produce sperm.

The cells were modified into what are known as pluripotent stem cells. These cells possess the capability to grow into any other kind of cell.

The pluripotent stem cells were then implanted into mice testes, leading to the production of the biological precursors to complete sperm.

"Infertility is remarkably common, affecting 10 to 15 percent of couples," says Renee Reijo Pera, who was the director of Stanford's Center for Reproductive and Stem Cell Biology during the research but is now vice president for research at Michigan State University.

"And the genetic causes of infertility are surprisingly prevalent among men. So progress in this area could potentially help thousands, if not millions, of couples around the world," says Pera, considered one of the globe's authorities in the field of stem cell research.

Writing in the journal Cell Reports, the researchers reported success into turning the skin-derived stem cells into what are known as "primordial germ cells" inside the mice testes. Those are the kinds of cells which, in humans, normally will develop to become healthy sperm.

The findings suggest the possibility that in the future infertile men might be treated by having cells from some other area of the body turned into stem cells and then implanted in their testes, although the researchers caution such treatment would need much addition research before it could be considered clinically viable.

"Because we used mouse and human cells together for this study, we didn't complete that pathway," Reijo Pera said. "We didn't actually produce sperm. And we would still have to look at this in humans to see how it will all work. So there's a long way to go before we might be able to actually do something with all of this."

Still, Reijo Pera said, she remains optimistic about the possibility of being able to create sperm cells out of a patient's own cells, sperm cells that would contain the patient's own unique genetic information to pass on to his children.