Coaxing More From Adult Stem Cells

(WebMD)  By undergoing various kinds of coaxing, adult bone marrow cells appear able to replace any cell in the body.

That hope is raised by three presentations at the annual meeting of the American Chemical Society, being held Sept. 10-14 in San Francisco.

The papers have three things in common:

First, the researchers used adult stem cells. This avoided the ethical questions raised by the use of embryonic stem cells.

Second, they showed that these adult stem cells, which ordinarily would have become blood cells, can instead become solid organ cells, or even nerve cells.

Finally, they taught these new tricks to the adult cells by changing the physical environment in which they grew.

Researchers at the University of California, Berkeley, used a kind of workout to give bone marrow cells the muscle they needed to become blood vessel cells. Berkeley scientists Kyle Kurpinski and colleagues got the cells to attach to an elastic membrane, which had grooves to get the cells to align the right way. Then the membrane constantly stretched and relaxed for several days.

Cells that exercised this way started to become smooth muscle cells — the kind of cells that make up blood vessels.

Kurpinski points out that in the body, stem cells attach to the walls of blood vessels. As blood is pumped through these arteries, the cells naturally stretch and contract. "If a cell cannot flex its muscles like Arnold Schwarzenegger, it cannot build its muscles," Kurpinski said in a news conference. "Gov. Schwarzenegger got big biceps by lifting dumbbells ... It works the same way for stem cells to become smooth muscle cells. They have to sit in culture day in and day out lifting weights."

Stem cells feel their environment. And what they feel determines what they become, reports Dennis E. Discher, Ph.D., professor of chemical and biomolecular engineering at the University of Pennsylvania, in a second presentation.

By growing cells in a soft, stiff, or rigid environment, Discher's team was able to get adult bone marrow cells to become more like soft nerve cells, rigid bone cells, or stiff muscle cells. To complete the process, Discher's team found the cells needed stimulation from the proper mix of chemical messengers.

Blood stem cells can, indeed, become many different kinds of cells, confirms E. Terry Papoutsakis, Ph.D., professor of chemical and biological engineering at Northwestern University, in the third report.

Simply by manipulating the conditions in which blood stem cells are grown, Papoutsakis and colleagues were able to make the cells take off in previously unexpected directions. "We demonstrate these cells can do more than is currently accepted," Papoutsakis said in the news conference. "There are several approaches to harness the potential of the billions of stem cells we make every day."

SOURCES: Papoutsakis, E. Abstract BIOT 459, Presentation to the 23rd national meeting of the American Chemical Society, San Francisco, Sept. 10-14. Discher, D. Abstract BIOT 463, Presentation to the 23rd national meeting of the American Chemical Society, San Francisco, Sept. 10-14. Kurpinski, K. and Li, S. Abstract BIOT 464, Presentation to the 23rd national meeting of the American Chemical Society, San Francisco, Sept. 10-14. News release, American Chemical Society. News conference with E. Terry Papoutsakis, Ph.D., professor of chemical and biological engineering, Northwestern University, Chicago; Dennis E. Discher, Ph.D., professor of chemical and biomolecular engineering, University of Pennsylvania, Philadelphia; and Kyle Kurpinski, University of California, Berkeley.

By Daniel DeNoon
Reviewed by Louise Chang