June 8 (Bloomberg) -- The intestine may contain numerous types of stem cells, a Nobel Prize-winning scientist said in a study that may add new layers of complexity to using the powerful cells in human treatments.

Stem cells that were thought to populate the entire intestine appeared only in the upper third of the long, tube- like organ, said Mario Capecchi, a University of Utah geneticist who led the study published today in the journal Nature Genetics.

Scientists and doctors are looking for ways to use stem cells, which can replace all the tissues in the body, to treat diseases. The study suggests that the intestine, and perhaps other organs, may contain a variety of stem cells that will need to be studied and carefully selected to develop such treatments, he said.

``What we have to do now is find out why these various stem cells are different and how that affects their function,'' he said June 6 in a telephone interview from his office in Salt Lake City.

All tissues in the body can trace their lineage back to embryonic stem cells that make any cell type. Organs contain more mature stem cells, called adult stem cells, that are able to maintain and repair the tissues in that structure alone.

Capecchi was studying adult intestinal stem cells using a genetic marker called Bmi1 that was thought to distinguish all stem cells in the organ. He found instead that most of the intestine doesn't contain cells with the marker, indicating that other stem cells in the intestine must take different forms.

The intestine may need multiple types of stem cells to make tissues that process different types of foods and perform various functions, he said.

``This may be true in other organs as well,'' he said. ``Any time you're working with adult stem cells you're going to have to take this into consideration.''

To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: June 8, 2008 13:00 EDT