The sonic hedgehog gene, best known for controlling embryonic development, also maintains the normal physiological state and repair process of an adult healthy lung, if damaged, according to new research.
Tissues are not all created equal in their ability to regenerate. Skin and blood cells are continually turning over, making entirely new populations of cells every few days. At the other end of the spectrum, heart and brain cells regenerate slowly, if at all, after injury. Between these two extremes are tissues such as the lung and liver, which have little cellular turnover in normal adults, but can regenerate extensively after injury. Such tissues, overall, are thought to be quiescent.