Last month, we wrote about the retraction of a 2005 paper suggesting that some adult stem cells might give rise to cancer. That, of course, would be a problem if researchers tried treating heart disease and other conditions with them. The paper’s authors retracted it, however, when it became clear that instead of being transformed — that’s the scientific word for “became cancerous” — the cells had simply become contaminated and overgrown with tumor cells used in research.
We had some questions for the authors of the original paper, and for the editor of the journal. Last week, we heard back from one of the paper’s authors, Javier Garcia-Castro, who had been on vacation without Internet access for weeks. In an email to Retraction Watch, Garcia-Castro wrote:
Certainly we have lost years of work for not having made these STR [short tandem repeat DNA] tests [which revealed the likely contamination]. It was our mistake and we have tried to express [this] to the scientific community.
Garcia Castro also forwarded a letter published in February in Experimental Cell Research in which he and his colleagues describe, in some detail, the experiments they performed to explain their results. There, they write:
Currently, the most plausible explanation for the MSC spontaneous transformation phenomenon we described is thus an artifact mediated by an unnoticed minimal cross-contamination of some of the original samples with HT1080 cells.
HT1080 is a line of cells with fibrosarcoma, a type of cancer.
We had asked Garcia-Castro why two of the original paper’s five authors hadn’t signed the retraction. Co-author Alison Lloyd said she was not involved in isolating the cells, nor with the subsequent DNA fingerprinting, so she didn’t feel it was appropriate for her to sign it, according to Garcia-Castro.
The other author, Daniel Rubio, “firmly believes that there was a real spontaneous transformation” of the cells, and that all of the tests, including short tandem repeat testing, “are not conclusive,” Garcia-Castro said.
Garcia-Castro said he wasn’t quite sure why Cancer Research had waited to publish his team’s retraction, which sat with the editor “for months” even as the journal published a related letter noting that many other findings in the field were likely due to contamination. Garcia-Castro and his colleagues — eager to set the scientific record straight — had asked to write a similar letter, but after Cancer Research said no, they decided to publish their letter in the other journal, Experimental Cell Research.
We didn’t hear back from the editor of Cancer Research when we asked for comment on our last post, and we’ve sent him another message along with a question about this too. Will update if we hear back.
Update, 9:30 Eastern, 9/9/10: The editor of Cancer Research forwarded our questions to the journal’s publisher, the American Association for Cancer Research, which declined comment.