Nature Magazine has concluded that a controversial University of Minnesota stem-cell study had flaws when it was published five years ago, but that the errors didn't affect the underlying conclusions, which drew headlines around the world.
The study, which found that adult stem cells may be as useful as embryonic stem cells in treating disease, had been under scrutiny since last year because of questions raised about its accuracy.
On Wednesday, the prestigious medical journal said it had conducted its own review of the study, and that despite some flawed data, the findings still hold up.
It also published a correction by the study's authors, most notably Dr. Catherine Verfaillie, a world-famous scientist who formerly led the university's stem cell institute.
In an email interview, she described Wednesday's report as a great relief. "As I have said before, I take responsibility for the factual errors, and am sorry about these," wrote Verfaillie from her home in Belgium. "Nevertheless I continue, and this was reinforced by the conclusions from Nature, to believe that our findings were correct."
Tim Mulcahy, the university's vice president for research, said the journal's review should "close the loop" on the controversy.
"Their reviews are highly respected for how thorough they are," he said. Last year, a university inquiry also found that part of the study was "significantly flawed" in the way it identified certain cells. But said it didn't have the expertise to assess how important that was.
The authors later submitted new data to correct the mistakes.
In a news release Wednesday, Nature said: "The retraction of Figure 1 does not negate the central findings of the paper that cells isolated in the manner described are self renewing and multipotent."
Other studies under review
The study was one of the first to raise hopes of a serious alternative to embryonic stem cells in medical research. Embryonic cells are controversial because the embryo must be destroyed to obtain them; while adult stem cells can be extracted from bone marrow and other organs without causing harm. Scientists are trying to use stem cells to treat cancer and other illnesses and repair damaged organs.
In February, though, the study came under fire when another journal, New Scientist, reported that Verfaillie and her colleagues had published the same data twice, labeled differently, in separate medical journals.
"We're pleased that the data have been corrected," said Peter Aldhous, the San Francisco bureau chief for New Scientist, of Wednesday's report. But he said some questions remain in the scientific community about the study's findings. "It's an interesting and exciting paper which has proved difficult to replicate, and that is still the case," he said.
Verfaillie disagreed, saying that "many labs are recreating similar results."
Meanwhile, the University of Minnesota is reviewing two other studies published by Verfaillie and her colleagues, as well as data published in a patent application, Mulcahy said. He said Verfaillie, who ran the university's stem cell institute for eight years, has acknowledged that there were errors in those papers as well. Verfaillie now heads stem cell research at Catholic University in her native Belgium, although she remains a part-time faculty member at the University of Minnesota.
"I am fully cooperating with them," she said of the ongoing inquiries. "And I hope that a clear answer will come forth on this soon."
The correction in the latest edition of Nature can be viewed online at www.nature.com/nature, under the heading Corrigendum.Still no news from all those researchers who are confident that embryonic stem cells are the future for their work. Sadly, most of our politicians are scientifically illiterate and listen to them. There is so much money riding on the wrong horse, embryonic stem cell research, that many lawyers will work overtime prove the UofMN study to be flawed in an attempt to recover foolish investments.