Cellular senescence is a normal consequence of aging, resulting from lifelong accumulation of DNA damage that triggers an end to cell replication. Although senescent cells no longer divide, they persist in their tissue of origin and develop characteristics that can hasten and exacerbate age-related disease. This series addresses the contribution of cellular senescence to cardiovascular, neurodegenerative, and arthritic disorders as well as the senescent phenotypes in various tissues and cell types. In addition to their cell-intrinsic effects, senescent cells develop the ability to negatively influence healthy neighboring cells and immune cells by secreting senescence-associated set of cytokines and mediators known as the SASP. These reviews also highlight ongoing efforts to accurately identify, target, and eliminate senescent cells or otherwise combat their deleterious effects in disease. One day, this work may provide the basis for therapies targeting aging cells in multiple organs.
Along with a general decline in overall health, most chronic degenerative human diseases are inherently associated with increasing age. Age-associated cognitive impairments and neurodegenerative diseases, such as Parkinson’s and Alzheimer’s diseases, are potentially debilitating conditions that lack viable options for treatment, resulting in a tremendous economic and societal cost. Most high-profile clinical trials for neurodegenerative diseases have led to inefficacious results, suggesting that novel approaches to treating these pathologies are needed. Numerous recent studies have demonstrated that senescent cells, which are characterized by sustained cell cycle arrest and production of a distinct senescence-associated secretory phenotype, accumulate with age and at sites of age-related diseases throughout the body, where they actively promote tissue deterioration. Cells with features of senescence have been detected in the context of brain aging and neurodegenerative disease, suggesting that they may also promote dysfunction. Here, we discuss the evidence implicating senescent cells in neurodegenerative diseases, the mechanistic contribution of these cells that may actively drive neurodegeneration, and how these cells or their effects may be targeted therapeutically.
Darren J. Baker, Ronald C. Petersen