Cells are not immortal, and that is a good thing. After a certain number of divisions, many human cells stop multiplying for good. They enter a state called replicative senescence, where growth ceases ...

CLEVELAND—Amyotrophic lateral sclerosis (ALS), known as Lou Gehrig’s disease, is an incurable neurological disorder affecting motor neurons—nerve cells in the brain and spinal cord that control ...

Imagine if our bodies could grow new organs throughout our entire lives. Plants do this constantly, thanks to tiny, powerful reservoirs of stem cells. But how do these cells know when to divide, and ...