The long-term hope is to treat patients with some sort of stem cell that could turn into beating heart muscle and replace dead cardiac tissue with fully functioning new cells.

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Normally, orderly waves of electric activity pass through the cardiac tissue, causing the heart muscle to contract.

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Anabolic steroids can lead to an expansion of the cardiac muscle, which can cause heart attacks.

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They found that the stem cells produced growth factors that traveled to the heart, in addition to stimulating the muscle itself to make growth factors that also improved cardiac function.

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He has managed to reprogram mouse connective-tissue cells so that they develop into cardiac muscle cells, and has tested them in the hearts of mice that have had heart attacks.

ECONOMIST: Stem cells and medicine: Repairing broken hearts | The