Fresh accusations have emerged that stem-cell researchers at the University of Minnesota-Twin Cities misrepresented their results in a published report and a patent application. In a paper published in Blood and in a patent based on findings reported elsewhere, the same image appears to have been used to represent the results of two or three separate experiments, New Scientist reported on Wednesday.

The work, led by Catherine Verfaillie, who has since moved to the University of Leuven, in Belgium, concerns adult stem cells. Dr. Verfaillie’s surprising results showed that some of the cells, found in bone marrow, could make a wide variety of tissues, like bone, blood, and cartilage. Previously they were thought able to make only a limited set of blood-cell types.

The questionable image, a photograph of a gel used to separate out proteins of different sizes, seems to appear twice in the paper. One image shows three blots of protein labeled ß-actin, a protein found in all of the cell types. An apparent mirror image of that gel is shown on the same page, but in the second instance, it is labeled collagen II, a protein found in cartilage. In the patent, the flipped image is said to represent a third protein, one specific to bone, New Scientist reported.

Dr. Verfaillie previously used a single image to represent two different experiments in a papers published in Nature and Experimental Hematology. An ethics review conducted by the University of Minnesota found that instance to be an unintentional mixup. Sanford Shattil, editor of Blood, told New Scientist that the journal would look into the new matter. —Susan Brown