Originally created 05/16/02

Scientists make stem cells work as liver tissue



First they made muscle. Then, stem cells taken from bone marrow helped rebuild diseased blood vessels. Next they reversed stroke damage.

Now University of Minnesota scientists have coaxed the cells to function as liver tissue.

The research, reported Wednesday in the Journal of Clinical Investigation, is the latest in a series intended to show that cells from children and adults can be reprogrammed to function in laboratory experiments as all of the body's major tissue types. Research is underway to learn whether they can perform the same magic in live patients, but widespread practical applications may be years away.

The new-found versatility of adult stem cells is prompting "a dramatic shift in thinking about cell regeneration," said the journal's editors in summarizing the significance of the research. If the research fulfills expectations, these cells could help cure diseases and reverse damage that leaves patients severely disabled.

For liver patients, the latest findings could offer hope on several fronts, said Dr. Catherine Verfaillie, director of the university's Stem Cell Institute and the lead scientist for the research.

The stem cells could help replace flawed tissue in patients with diseased or damaged livers. The cells also could be inserted in biomechanical livers that sustain patients whose livers have failed; currently, pig cells are being tested for such devices. In yet another use, the cells could serve as stand-ins for a real liver to test whether new drugs are toxic.

But first the cells need to pass more tests, Verfaillie said. The research reported Wednesday involved taking primitive bone marrow cells - called multi-potent adult progenitor cells - from humans, mice and rats. The cells were cultured in the laboratory to induce them to behave as though they had come from a liver. They secreted albumin, the most abundant protein made by the liver, and they also displayed "the whole detoxifying set of tools that you would find in a normal liver," Verfaillie said.

Next, the cells must be tested in laboratory animals with liver problems, Verfaillie said. That research is already underway and could be finished within two years, she said.

Meanwhile, the next challenge for the overall research is to show that the bone marrow cells can work as nerve cells. Those studies have been completed and are awaiting final review by other scientists, Verfaillie said. If they pass muster, the university team will be able to claim that it has isolated cells that can be trained to mimic any of the body's major tissue groups.

"Whatever we have tested so far appears to be working," she said.

(Distributed by Scripps Howard News Service, http://www.shns.com.)