Two studies shed doubt on the reported ability of certain transplanted stem cells to repair damaged heart tissue. The papers, published online by Nature this week, find no evidence to suggest that haematopoietic stem cells, which usually produce blood cells, can turn into heart cells after injection into the organ.
Two teams, led by Charles E. Murry and Leora B. Balsam, injected bone-marrow-derived haematopoietic stem cells into the damaged hearts of living mice. Both groups then followed the injected cells' fate via the use of various marker proteins. Although some of the transplanted cells seemed to survive, they did not appear to differentiate into new heart muscle cells. Instead they matured into cells of the traditional blood lineage. Balsam and colleagues observed modest benefits in some aspects of heart function after the procedure, but suggest that these may be from the stimulation of new blood vessels in the heart.
The results raise a cautionary note for interpreting the results of ongoing clinical studies where haematopoietic stem cells are injected into the heart after a heart attack.
Loren Field (co-author of Dr Murry)
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Stanford University School of Medicine
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Murry paper Online.
Balsam paper Online.
(C) Nature press release.
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