CXCL12 and endothelial dysfunction: Given the observation that select circulating SASP factors changed with aging and senolytic treatment with fisetin, we next aimed to evaluate the functional role of the circulating SASP environment on age-related endothelial dysfunction and the specific effects of CXCL12 as a candidate circulating SASP factor that might be responsible for transducing the effect of the circulating environment on endothelial function.