MINNEAPOLIS — A scientific panel says a 2002 study that suggested adult stem cells might be as useful as embryonic ones was flawed and its conclusions may be wrong, a finding that raises questions about the promise of a less controversial source for stem cells.
The research by Catherine Verfaillie at the University of Minnesota concluded that adult stem cells taken from the bone marrow of mice could grow into an array of biological tissues, including brain, heart, lung and liver.
So far only embryonic stem cells, which are commonly retrieved by destroying embryos at an early stage of development, are known to hold such regenerative promise. Many scientists believe they might one day be used to treat certain diseases and other conditions.
Opponents of stem cell research seized on the 2002 findings as evidence that stem cell science could move forward without destroying embryos. But Verfaillie has acknowledged flaws in parts of the study after inquiries from the British magazine New Scientist, which first publicized the questions last week.
A panel of experts commissioned by the university concluded that the process used to identify tissue derived from the adult stem cells was "significantly flawed, and that the interpretations based on these data, expressed in the manuscript, are potentially incorrect," according to a portion of the panel's findings released by the university.
The panel concluded that it wasn't clear whether the flaws mean Verfaillie's conclusions were wrong. It also determined that the flaws were mistakes, not falsifications.
Tim Mulcahy, vice president of research at the university, said it would be up to the scientific community to decide whether Verfaillie's study still stands up.
"From her perspective, the findings stand. I think the scientific community will have to make their own opinion," he said.
Other researchers have been unable to duplicate Verfaillie's results since the 2002 publications, increasing their skepticism about her claims. But that may only be an indication of how difficult the cells are to work with, said Amy Wagers, a Harvard University stem cell researcher who was not involved in the investigation.
Verfaillie did not respond to a phone message left with her current employer, the Catholic University of Leuven in Belgium. She told the Star Tribune of Minneapolis in a story published Friday that the problem was "an honest mistake" that did not affect the study's conclusions about the potential of adult stem cells.
Her research was scrutinized after a writer for New Scientist noticed that some data from the original 2002 article in the journal Nature duplicated data in a second paper by Verfaillie around the same time in a different journal, even though they supposedly referred to different cells. Verfaillie said the duplication was an oversight and said she notified the University of Minnesota, which convened the panel to take a closer look at the research.
The editor of the London-based scientific journal Nature said in a statement, "We are in touch with the author and investigating the problems that have been mentioned. We have no further comment."
Dr. Diane Krause of Yale University, who (like Verfaillie) has studied using bone marrow as an alternative to embryonic stem cells, said she believes Verfaillie's research will hold up, despite being hard to repeat.
"When it comes to Catherine, she's impeccable. She's one of the most careful scientists I know," Krause said.
Nigel Cameron, who runs the Institute on Biotechnology and the Human Future and is a bioethics professor at Chicago-Kent College of Law in the Illinois Institute of Technology, said scientists who have been trying to find a middle way on stem cells have seen their work seized by one side or the other for their own advantages. "This is a fascinating example of the way in which science is becoming politicized, on both sides of this debate," said Cameron, who supported President Bush's 2001 ban on federal dollars spent on deriving new stem cells from fertilized embryos. "It's no longer scientists in white coats coming up with facts. There are uses being made of the facts on all sides, and I think it's quite problematic."