Stem-cell 'secret of youth' found

A humble marine snail has helped scientists to unravel the signals that keep stem cells young.

Human embryonic stem (ES) cells can give rise to almost all of the body's different cell types. They could eventually provide patients with replacement tissues - but there are some roadblocks that currently prevent researchers from putting the cells into patients' bodies.

One problem is that scientists don't yet know how to control the cells' transformations into other types. Another is that the cells cannot be grown without help from mouse cells, which means that they could be contaminated with mouse proteins.

Ali Brivanlou of Rockefeller University in New York says that he and his colleagues may have found a partial solution to these problems. Brivanlou treated ES cells with a chemical, nicknamed BIO, from a sea snail.

BIO stopped ES cells turning into specialized adult cells, Brivanlou and his colleagues found. BIO works by activating a set of protein signals - called the Wnt pathway - in the ES cells1.

The Wnt pathway is known to be involved in development. Earlier this year, researchers reported that it also prevents blood-forming stem cells from turning into other cell types2.

The discovery could be useful to scientists who are trying to make therapies based on stem cells. By controlling the Wnt pathway, they could tell the cells when to stay young, and when to specialize.

Using chemical compounds such as BIO might also eliminate the need for mouse support cells, which normally ooze proteins that stop stem cells specializing. Many research groups are looking for alternative ways to wean human cells off mouse feeder cells.

So far, Brivanlou has only monitored the cells for a few cycles of division, so he doesn't know how long BIO can sustain them. But he hopes that further studies will help scientists discover how to manipulate stem cells at will.

"If we want to make stem cells into therapies, we're going to need cell lines that were never grown in any foreign proteins," Brivanlou says. "This work should help us take stem cells into that clinical setting."

References
1. Sato, N., Meijer, L., Skaltsounis, L., Greengard, P. & Brivanlou, A. H. Maintenance of pluripotency in human and mouse embryonic stem cells through activation of Wnt signalling by a pharmacological GSK-3-specific inhibitor.Nature Medicine, published online, doi:10.1038/nm979 (2003).|Article|

1. Reya, T. et al. A role for Wnt signalling in self-renewal of haematopoietic stem cells. Nature, 423, 409 - 414, doi:10.1038/nature01593 (2003).