Florida State University : Research in Review

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Stem Cell Short-Cut?
Bryan Cuevas

In the fast-paced world of today's scientific marketplace, few discoveries have sparked as much debate as the remarkable promise for curing disease found in embryonic stem cells.

Now, a new study, led by David Gilbert, professor of biological science, could make it easier to engineer artificial stem cells from adult tissue allowing for stem cell research without using human embryos.

One of the keys to taking adult tissue back to an embryonic state is a step-by-step understanding of what happens as stem cells become specialized.

A mammalian cell contains a lot of DNA—a gigantic molecule that would stretch to nine feet if uncoiled. To fit inside a nucleus, it must be folded thousands of times.

To explain DNA folding, Gilbert offers the analogy of organizing an office. Books and materials rarely used get put on harder-to reach shelves while important items are placed at eye level.

By analyzing DNA replication, Gilbert and a team of molecular biologists focused on this rearrangement of DNA as embryonic stem cells from mice developed into specialized cells.

What Gilbert and his colleagues discovered is that the order in which segments of DNA get copied during cell division is different between stem cells and differentiated cells. In fact, the order is unique to each cell type, whether stem, heart, or nerve.

The order in which genes get copied also determines where they get packaged in the nucleus, with DNA copied later tending toward the edges. As arrangement ultimately affects what genes get turned on, this placement is the organizational equivalent of getting stuffed into a bottom drawer and forgotten.

Interestingly, the genes for pluripotency—the coveted ability of stem cells to become most any other cell in the body—were discovered among those on the outer rim of differentiated cells. This suggests that, by replicating late, they were overcome with dense packaging and inactivated, Gilbert said.

With a catalogue of organizational fingerprints for different kinds of cells, and a detailed map to the buried treasure of pluripotency genes, researchers can now engineer tissues and coax adult cells back to an embryonic state with more efficiency and control than they have previously been able to do. After all, Gilbert says, the true application of stem cell research is "to study human disease from human tissue [taken from] the actual person who has the disease."

Gilbert's work appeared in the journal PLoS Biology last fall. —E.S.To learn more about Gilbert's research, visit http://gilbertlab.bio.fsu.edu/.