It is said that senescent cells, also called zombie cells, can cause biological ageing. These senescent cells are also killed by immune cells. It does not make sense as to how they cause ageing if they are removed?
In an healthy individual, senescent cells are likely removed by the immune system. However, as we age, our immune system becomes impaired and may no longer be able to kill senescent cells. Senescent cells can then accumulate and promote age-related diseases.