Senescent cells are non-dividing but metabolically active, can persist in tissues for decades, and secrete inflammatory signals.

“skin is full of senescent cells. These are zombie-like cells that reach a point where their epigenome is so dysregulated that they check out of the system, they stop dividing. - They're no longer producing. - Right. They don't divide and we can stain them blue with a dye called beta-galactosidase. And they're pretty common in an older person. The problem is that they secrete these inflammatory factors and also what are called mitogens that stimulate cancer.”