Collagen V regulates the size of heart scar tissue after a heart attack
After a heart attack, damaged heart muscle is replaced by connective scar tissue. A critical part of the healing process, this also affects health outcomes after recovery, with larger scars associated with higher mortality. Scar tissue is primarily composed of collagens but, paradoxically, researchers recently discovered that the absence of one of these proteins, collagen type V, leads to greater scarring. In mice lacking collagen V, the scar structure is altered (pictured, right, with disorganised fibres, compared to a healthy scar, left), and becomes too flexible. As the heart expands to pump blood, the scar swells with it, which encourages secretion of more collagens to combat this stretching, causing continued cycles of scar expansion. Promisingly, treatment with an existing drug, cilengitide, originally developed as cancer medication, can break this feedback loop, suggesting further research on collagen V could lead to better ways of dealing with scarring after heart attacks.
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