Senescent cells accumulate in the brain with age, and these cells generate chronic inflammation in brain tissue. Neurodegenerative conditions such as Alzheimer's disease are known to prominently involve inflammation in the progression of pathology. At least one senolytic treatment, the combination of dasatinib and quercetin, can pass the blood-brain barrier to destroy senescent cells in the brain, and has been shown to reduce inflammation and reverse tau pathology in mouse models of Alzheimer's disease. Researchers here add more data to this subject, clearing senescent cells from the brains of aged mice, and finding that this reverses a sizable fraction of the age-related loss of cognitive function that normally takes place. At least one human trial has started up to test the use of dasatinib and quercetin to treat Alzheimer's disease; this is a very promising area of study.
Cellular senescence is characterized by an irreversible cell cycle arrest and a pro-inflammatory senescence-associated secretory phenotype (SASP), which is a major contributor to aging and age-related diseases. Clearance of senescent cells has been shown to improve brain function in mouse models of neurodegenerative diseases. However, it is still unknown whether senescent cell clearance alleviates cognitive dysfunction during the aging process.
To investigate this, we first conducted single-nuclei and single-cell RNA-seq in the hippocampus from young and aged mice. We observed an age-dependent increase in p16Ink4a senescent cells, which was more pronounced in microglia and oligodendrocyte progenitor cells and characterized by a SASP. We then aged INK-ATTAC mice, in which p16Ink4a-positive senescent cells can be genetically eliminated upon treatment with the drug AP20187 and treated them either with AP20187 or with the senolytic cocktail Dasatinib and Quercetin. We observed that both strategies resulted in a decrease in p16Ink4a exclusively in the microglial population, resulting in reduced microglial activation and reduced expression of SASP factors.
Importantly, both approaches significantly improved cognitive function in aged mice. Our data provide proof-of-concept for senolytic interventions' being a potential therapeutic avenue for alleviating age-associated cognitive impairment.