Scientists have recently discovered a type of stem cell called XEN, also referred to as iXEN. They believe that this discovery can lead to new ways of studying reproductive problems and birth defects.

When an embryo produces stem cells, it also subsequently produces XEN cells. These cells are said to be the makers of embryonic tissues, which have an indirect relationship with the development of a fetus inside its mother's womb.

With this knowledge, Michigan State University researchers led by Tony Parenti came up with the hypothesis that XEN cells are also produced during the reprogramming of mature adult cells into induced pluripotent stem cells (iPS), which mimic the defining properties of stem cells that come from embryos.

Through the studies of iPS cultures, the team was able to prove that iXEN cells are also flourishing alongside the iPS cells when adult cells are being reprogrammed.

What fascinated the researchers further is the fact that these iXEN cells have been there all along — whenever research on iPS is done. However, these iXEN cells had been considered leftovers, thus, scientists would have to throw them out after the iPS production process.

"Other scientists may have seen these cells before, but they were considered to be defective, or cancer-like," Parenti said. "Rather than ignore these cells that have been mislabeled as waste byproducts, we found gold in the garbage."

With further tests using mice models, Parenti and his team also found out that these XEN cells are not cancer-like and that they could alter the genes inside the cells. With alteration, they were able to increase the production of iPS cells while reducing that of iXEN cells.

"Nature makes stem cells perfectly, but we are still trying to improve our stem cell production. We took what we learned by studying the embryo and applied it to reprogramming, and this opened up a new way to optimize reprogramming," Parenti explained.

The next step now for the team is to put the test on humans. Their findings were reported in Stem Cell Reports.