Why don't you hear about people getting heart cancer?
The historical explanation is that, unlike most other cells in the body, heart muscle cells don't divide. Since it's during cell division that cancer-causing mutations can occur, without cell division, this theory goes, there's hardly any chance to incur harmful mutations.
But, as with much else in biology these days, things turn out to be not quite so simple.
Heart cells, called myocytes, do obviously divide as we grow - "to make new cells during embryonic development, but after birth, as childhood development progresses, these cells have reduced abilities to divide," said Lewis C. Cantley, a biophysical chemist who is director of the Cancer Center at Beth Israel Deaconess Medical Center. Certain cardiac tumors do occur in infants and in utero, and often resolve without any medical intervention as cellular signals that turn off cell division kick in.
But even in adults, heart cell division is not completely absent, said Dr. Steven Colan, associate director of cardiology at Children's Hospital. Indeed, if heart muscle cells never divided, there would be no way for the heart to repair itself after a heart attack or other tissue damage. In other words, heart cells, like nerve cells in the brain, do divide, but less often than most other cells, he said.
The other distinguishing feature of heart cells is that, like nerve cells in the brain that fire incessantly, heart cells are metabolically active every minute of life. That constant activity, said Colan, means that these cell types rarely get a chance to "put themselves into a resting state and devote their resources to dividing."
Precisely because of heart cells' relatively low division rate, pharmaceutical companies are working on ways to stimulate heart cells to divide, in hopes that this would help the heart recover better after damage.
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