Once they start dividing, stem cells are likely to turn into nerve, muscle, or other tissues--and they stop being stem cells.

FORBES: Small Stem Cells Find Big Backers

Injecting stem cells into the heart muscle carries the risk of arrhythmia, said Techung Lee, associate professor of biochemistry at the State University New York at Buffalo.

CNN: Stem cells may offer promise for damaged hearts

About four months after each patient's original operation, when their hearts had stabilised, Dr Bolli used a catheter to deliver 1m of the newly bred stem cells to their damaged heart muscle.

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

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.

CNN: Stem cells may offer promise for damaged hearts

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.

FORBES: Using Thigh Muscle To Fix The Heart

Except that researchers still couldn't prove that the heart, nerve, muscle and other cells they made from the iPS cells were exactly like the ones generated from the embryonic stem cells.

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