Cell Senescence and Cerebral Small Vessel Disease in the Brains of People Aged 80 Years and Older

Cerebral small vessel disease (cSVD) in penetrating arteries is a major cause of age-related morbidity. Cellular senescence is a molecular process targeted by novel senolytic drugs. We quantified senescence in penetrating arteries and tested whether myocyte senescence was associated with cSVD. We immunolabeled subcortical white matter of older persons (age 80-96years, n=60) with minimal AD, using antibodies to 2 established senescence markers (H3K9me3, gamma H2AX) and a myocyte marker (hSMM). Within the walls of penetrating arteries (20-300 mu m), we quantified senescence-associated heterochromatic foci (SAHF)-positive nuclei, cell density (nuclei/mu m(2)), and sclerotic index (SI). Senescent-appearing mural cells were present in small arteries of all cases. cSVD cases exhibited a lower proportion of senescent-appearing cells and lower area fraction (AF%) of SAHF-positive nuclei compared to controls (p=0.014, 0.016, respectively). cSVD severity and SI both correlated negatively with AF% (p=0.013, 0.002, respectively). Mural cell density was lower (p<0.001) and SI higher (p<0.001) in cSVD, relative to controls. In conclusion, senescent myocyte-like cells were universal in penetrating arteries of an AD-free cohort aged 80 years and older. Senescent-appearing nuclei were more common in persons aged 80 years and older without cSVD compared to cSVD cases, indicating caution in senolytic drug prescribing. Myocyte senescence and cSVD may represent alternative vessel fates in the aging human brain.