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Definitive Proof: New Cells Can Develop in the Heart

Some human organs can regenerate new tissues. However, the conventional view has been that this cannot occur in most organs, including the heart.

Last year, an international team found replicating cells in injured myocardium. Now, the same team reports startling findings in 8 female hearts that were transplanted into males. Myocytes, arterioles, and capillaries in the transplanted female hearts contained a minimum of 7% to 10% male (Y-chromosome-positive) cells from the host. Particularly in the early days after transplantation, very early multipotent cells abounded in the ventricles. Equally important, such early multipotent cells also were found in control (i.e., non-transplanted) hearts, although in smaller numbers. The antigenic markers present on the cells were consistent with 2 hypotheses: First, some of these early multipotent cells indisputably came from the recipients (either from residual atrial tissue or from bloodborne stem cells). Second, some multipotent cells already resided in the transplanted hearts.

Comment: The findings of this landmark study overturn conventional dogma. They are just the latest evidence indicating that humans may have undifferentiated progenitor cells resident in both tissues and circulation. These cells help repair injury and may help organs remain healthy even in the absence of frank injury. If the chemical signals that control organ-specific regeneration can be identified and controlled, the implications for clinical medicine are profound.

— Anthony L. Komaroff, MD

Published in Journal Watch General Medicine February 1, 2002

Citation(s):

Quaini F et al. Chimerism of the transplanted heart. N Engl J Med 2002 Jan 3; 346:5-15.

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• Medline abstract (Free)

Bolli R. Regeneration of the human heart -- No Chimera? N Engl J Med 2002 Jan 3; 346:55-6.

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• Medline abstract (Free)

Schwartz RS and Curfman GD. Can the heart repair itself? N Engl J Med 2002 Jan 3; 346:2-4.

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• Medline abstract (Free)