Senolytic Treatment With Fisetin Reverses Age-Related Endothelial Dysfunction Partially Mediated by SASP Factor CXCL12.

Advancing age is the strongest risk factor for cardiovascular diseases (CVDs), primarily due to progressive vascular endothelial dysfunction. Cellular senescence(definition) and the senescence-associated secretory phenotype (SASP) contribute to age-related endothelial dysfunction by promoting mitochondrial oxidative stress and inflammation, which reduce nitric oxide (NO) bioavailability. However, the molecular changes in senescent endothelial cells (ECs) and their role in endothelial dysfunction with aging remain unclear. As such, we sought to identify the EC-related signaling pathways, endothelial-associated SASP factors, and their impact on endothelial function with aging. Single-cell transcriptomics was performed on aortas from young (6mos) and old (27mos) female and male mice with and without in vivo senolytic treatment with fisetin (100 mg/kg/day administered intermittently) to characterize EC senescence and transcript expression changes. Circulating levels of SASP factors were measured to assess systemic changes associated with aging and fisetin treatment. Plasma exposure experiments were conducted in isolated mouse arteries and cultured human aortic ECs to determine the causal role of the circulating SASP milieu and specific SASP factors in mediating endothelial dysfunction and underlying mechanisms of action. Senescent ECs exhibited elevated expression of SASP factors, particularly Cxcl12, which was reversed by fisetin supplementation, with responses also reflected in circulating CXCL12 concentrations. Plasma from old mice impaired endothelial function by inducing vascular cell senescence, reducing NO, increasing mitochondrial oxidative stress, shifting receptor and promoting endothelial-to-mesenchymal transition-effects partially driven by CXCL12 and prevented by fisetin. These results identify the SASP and CXCL12 as drivers of age-related endothelial dysfunction and establish mechanisms of senolytic intervention with fisetin supplementation.