What are the differences between quiescent and senescent cells?

Basis of differentiation

Quiescent cells

Senescent cells

Definition

cells that exist in the quiescent state, which is a reversible state of cell cycle arrest   

cells that exist in the senescent state, which is an irreversible state of stable cell cycle arrest 

Response to stress

Are able to withstand cellular stressors and survive harsh conditions

Are less capable of coping with stress and exhibit susceptibility to DNA damage, oxidative stress, and other stressors 

Replicative potential 

Quiescent cells have the ability to re-enter the cell cycle 

Do not have the ability to re-enter the cell cycle 

Causes/mechanism

Quiescence occurs due to lack of nutrients and growth factors

Senescence occurs due to cellular aging or severe DNA damage 

Cellular phenotype

Exhibit reduced metabolic activity, small cell size, low RNA and protein synthesis. They are able to maintain their cellular phenotype and functions while awaiting external cues for activation

Exhibit enlarged and flattened morphology of cells, with altered chromatin structure, altered gene expression patterns, and increased senescence-associated Beta-galactosidase activity