1th quarter 2005

New approaches to the treatment of myocardial infarction

The heart contains stem cells as well

Myocardial infarctions can take very different courses. A decisive prognostic criterion is the size of the area of dead heart muscle. Generally speaking, the following rule of thumb applies: when more than a billion heart muscle cells are destroyed by a myocardial infarction, there is a very high chance that the patient will die. If the infarction is less severe, the person is more likely to survive. However, the dead cardiomyocytes are not adequately replaced, because mature cardiomyocytes no longer divide. At the site of the infarction simple scar tissue is formed which does not contribute to cardiac function. This has been known for a long time, and it has been assumed that the heart essentially cannot regenerate.

These old tenets have been repeatedly challenged in recent years. In February 2005, a research team from San Diego, Philadelphia and Freiburg jointly reported the first successful demonstration of cells within the heart which can divide and mature into heart muscle cells. These cardioblasts, as they are called, are adult stem cells and harbour an enormous potential for the treatment of various forms of heart disease:

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  Cardioblasts are found predominantly in the atria, sites from where tissue can be excised without many problems. Cardioblasts from the excised atrial tissue could then be cultured and subsequently implanted at certain sites within the heart, e.g. infarct scars.
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  Alternatively, it may be feasible to stimulate cardioblasts directly by new kinds of drugs.

Cardioblasts present an especially attractive therapeutic concept because they have two major additional advantages:

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  Compared to other types of stem cells they can only mature into cardiomyocytes. This avoids the danger of false tissue differentiation (e.g. bone or tumour formation within the heart).
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  The cardioblasts are obtained from the respective patients themselves: there is thus no problem of rejection as would occur in conventional cardiac transplantation.

For these reasons it presents a very promising treatment concept for all forms of heart disease in which the original cardiomyocytes no longer fulfil their function. It can be taken for granted that intensive research will be conducted in this direction, ultimately also because the treatment of heart disease represents a multi-billion Euro market. Clinical trials in humans during the next five years can be easily imagined.