Stem cells found in adult marrow

Researchers believe adult stem cells have the potential to aid in organ transplant therapies.

Mike Enright

After facing several years of doubt and skepticism from some of her colleagues, a University researcher’s hard work and persistence might finally pay off.

Over the past several months, University scientists, led by Stem Cell Institute Director Catherine Verfaillie, have published a number of

studies detailing advances in research using multipotent adult progenitor cells, or MAPCs, a kind of adult stem cell found in bone marrow.

In their newest study, published Monday in the Journal of Experimental Medicine, Verfaillie and her associates successfully transplanted MAPCs into mice lacking an immune system.

Once implanted, the MAPCs created entirely new, functioning immune systems in the rodents.

“This is the first time the MAPCs were able to completely replace the blood-making system in an organism,” Verfaillie said in an e-mail statement from Belgium.

She called the discovery significant for several reasons – one being the research provides hope for possible future therapies to aid in organ transplants.

“Second, the research offers more evidence that these cells, while difficult to work with, exist and function as we first described in the journal Nature in 2002,” Verfaillie said.

Since she first published an article about the potential of MAPCs more than four years ago, many in the scientific community have questioned her claims about how the cells work and, in some instances, their very existence.

One of those skeptics is Irving Weissman, a professor of pathology and developmental biology at Stanford University and a co-author of the report.

A strong proponent of embryonic stem cell research, Weissman said he agreed to work with Verfaillie because he thought it was important she test her hypothesis, and had she done it alone, some of their peers might have been suspicious of her findings.

So he had a mutual colleague bring some of the cells Verfaillie had grown to his California lab, where they injected them into the test mice, Weissman said.

“(My colleague) came into my office a month or two later and said, ‘You won’t believe this, but it looks like the MAPC cells gave rise to blood cells,’ ” he said.

And while he said the results surprised him a bit, they didn’t completely win him over.

“We know that there are not enough (MAPCs) by themselves to give to a patient to recover their blood-forming or immune system,” he said. “You have to have a patient’s own bone marrow to get them over the hump.”

Weissman said there is still a lot of research to be done before one could think of any practical possibilities for MAPCs, and it will probably be a number of years before any treatments are realized.

More research

In other stem cell news, Dr. Bruce Blazar, a University pediatrics professor and co-author of Verfaillie’s paper, has also successfully replaced the immune systems of mice using MAPCs.

Additionally, Blazar said his lab’s continued research determined the stem cells did not mutate into malignant, tumor-causing cells after being injected into the mice.

“There has always been concern that when a cell is grown in vitro and doubles 80 times that that cell may have developed into a malignant cell,” he said.

Along with Blazar’s findings, in recent months Verfaillie and colleagues have isolated MAPCs from pig bone marrow and also used them to make smooth muscle cells.

Verfaillie said discovering the cells in pigs could be helpful in future testing because swine are so physiologically similar to people, and one day scientists might be able to create functional tissue in a lab based on their MAPC smooth muscle findings.