The role of microglial cellular senescence in the aging and Alzheimer diseased brain.

With each cell division, telomeres progressively shorten until they reach a critical length, at which point the cells enter cellular senescence. Microglia, a non-neuronal cell type residing within the central nervous system (CNS), play vital roles in maintaining neuronal function, health, and survival in both the normal and pathological CNS. A recent article described an increased incidence of microglial cytoplasmic structural abnormalities (i.e., swelling, twisted and shortened processes, and fragmentation) and dystrophy occurring in the cerebral cortex of human brains with age. These results suggest that microglial dystrophy may be a result of, or contribute to, their senescence, which in turn may impair their neuron-sustaining functions and ultimately lead to neuronal cell death.