Stem cells, found in male testicles, may be used to create tissue samples to help men fight off disease.

Using spermatogonial progenitor stem cells (SPCs), which lie within a specific area of the testes and generate the precursors to sperm, researchers from the Weill Cornell Medical College in New York City were able to develop working cells and tissue types.

The SPCs, obtained from mice testes, were redirected in the lab to form multi-potent adult spermatogonial-derived stem cells (MASCs). These cells went on to develop working blood vessel (endothelial) cells and tissue, cardiac cells, brain cells and a number of other cell types.

"What's really novel about our work is that, unlike induced pluripotency, these mouse SPCs do not require any addition or tweaking of genes to get them to form the multi-potent cells (MASCs) that then go on to produce all of these cell types," said senior author Dr. Shahin Rafii, director of the Ansary Stem Cell Center for Regenerative Medicine at Weill Cornell Medical College, in a news release. "Some hurdles remain, of course. We have to replicate these findings in humans, and we haven't discovered the exact switch that would allow us to control SPC development on demand. Nevertheless, it appears that these unique specialized spermatogonial cells could be an easily obtained and manipulated source of stem cells with exactly the same capability to form new tissues that we see in embryonic stem cells."

In the past, researchers have also used genetic manipulation to reprogram adult cells derived from connective tissue to test stem cell development. This induced pluripotency, or reprogramming, resulted in multi-potent stem cells that carried an increased risk of transforming into malignant cells. In their experiments, the Weill Cornell team concocted the perfect in vitro biochemical environment for the SPCs, which included helper cell types and growth factors, which developed into different cell types.

Cells are left to soak in cell cultures and eventually grew into multi-potent adult spermatogonial-derived stem cells (MASCs). The Weill Cornell saw MASCs change into a full range of cell types in mouse-tissue and in vitro studies."We took them furthest when it came to endothelial cells," says Dr. Daylon James, a co-author and investigator in Dr. Rafii's laboratory. "In experiments in live mouse tissue, we were able to show that these MASC-derived endothelial cells did more than just form — they also joined up with, and functioned alongside, other blood vessels."

The MASCs also produced contractile cardiac cells, neurons, and muscle cells in the laboratory, but there are still some challenges for researchers. "We still don't understand the exact biochemical and genetic switch that tells the cells to become MASCs, according to Dr. Seandel, a switch he said will be crucial to creating MASCs on a routine basis.