Munk, Rachel

Background: Vascular endothelial dysfunction is a key antecedent to cardiovascular diseases (CVD) in older adults. Reduced nitric oxide (NO) bioavailability secondary to excess mitochondria-related reactive oxygen species (mitoROS) bioactivity are key mechanisms of endothelial dysfunction with aging. Cellular senescence is a state of largely irreversible cell cycle arrest that drives endothelial dysfunction. This occurs in part through secretion of bioactive factors into serum, collectively referred to as the circulating senescence-associated secretory phenotype (SASP), that promote excess mitoROS and reduce NO. We have shown fisetin improves endothelium-dependent dilation in old mice by reducing cellular senescence and mitoROS. Here, we sought to translate our preclinical findings to older adults. Hypotheses: We tested the primary hypothesis that intermittent fisetin treatment would improve endothelial function in older adults and that this would be mediated by reductions in mitoROS and associated with lower cell senescence. We also determined if fisetin altered the serum to improve endothelial cell (EC) NO and reduce whole-cell ROS and mitoROS ex vivo. Exploratory analyses assessed if fisetin changed circulating SASP factors. Methods: In a randomized, placebo-controlled, parallel-group design pilot trial, 41 older men and postmenopausal women were randomized to fisetin (2 mg/kg/day) (age: 71±1 yrs [mean±SEM], n=22 [13 W]) or placebo (age: 71±1 yrs, n=19 [12 W]) administered in an intermittent manner (2, 3-day dosing periods separated by 14 days). Outcomes were measured at baseline and 1-3 weeks after the final dose. Endothelial function was assessed as brachial artery flow-mediated dilation (FMDBA). The change in FMDBA with an acute supratherapeutic dose (160mg) of the mitochondrial antioxidant MitoQ was used to assess mitoROS-related inhibition of endothelial function. Gene expression of cellular senescence markers Cdkn1a (encodes p21) and Lmnb1 (encodes Lamin B1) were assessed in peripheral blood mononuclear cells (PBMCs) by Q-PCR. Human aortic ECs (HAECs) in culture were exposed to 10% participant serum for 2 hrs; acetylcholine (ACh)-stimulated NO production (DAR-4M-AM) and basal whole-cell ROS (CellROX) and mitoROS (MitoBright Deep Red) bioactivity were assessed via immunofluorescence. Luminex analyses (Biotechne) measured circulating levels of SASP factors in serum. Results: FMDBA was improved by 41% with fisetin (pre: 3.9±0.4%, post: 5.5±0.5%, P< 0.0001), but unchanged with placebo (pre: 4.4±0.5%, post: 4.5±0.4%) (group x time interaction effect: P< 0.01). Similar efficacy was observed in men and women. Acute MitoQ enhanced FMDBA at baseline and after placebo (all P< 0.05) but led to no further improvements in FMDBA after fisetin treatment. Consistent with lower cell senescence, expression of Cdkn1a was reduced (P< 0.05) by 12% and expression of Lmnb1 increased (P=0.06) by 16% in PBMCs collected after fisetin but not placebo. Compared with pre-intervention, serum collected after fisetin, but not placebo, increased HAEC ACh-stimulated NO by 6% (P< 0.01) and lowered whole-cell and mitoROS bioactivity by ~10% (both P< 0.05). Protein levels of CXCL12 in serum were 5% lower (P< 0.05) after fisetin compared with pre-intervention and after placebo. Traditional cardiometabolic risk factors were unchanged. Conclusions: Intermittent fisetin treatment improves vascular endothelial function in older adults in part by suppressing mitoROS. These effects are linked to reduced cell senescence and select changes to the circulating SASP. Funding: AHA 23CDA1056582; NIH F31AG087709; NIH/NCATS CTSA UL1TR002535; Life Extension® provided fisetin (BioFisetin) and placebo. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Abstract Studying cardiovascular senescence is crucial for understanding disease-related changes in the cardiovascular system and their impact on health and disease. To systematically investigate the heterogeneity of senescent vascular cells in atherosclerosis, we employed the senescence reporter mouse p16tdTomato+/-, overexpressed PCSK9 and fed a high-fat diet (HFD) to induce atherosclerosis, and treated them with the senolytic drug ABT-737. Whole-aorta, single-cell RNA-sequencing (scRNA-seq) and Gene Set Enrichment Analysis (GSEA) using the SenMayo panel uncovered 10 cell clusters displaying senescent features, although not ‘classical’ senescence markers, that were reduced by treatment with ABT-737. Unbiased subclustering revealed subsets of cells increasing by HFD and reduced by ABT-737 treatment that expressed unique transcripts Spp1, Ctsb, and Tnfrsf11b mRNAs. Spatial analysis of these RNAs identified senescent cells in the cap and core of brachiocephalic arteries from atherosclerotic mice. Our results uncover a vascular-specific transcriptomic signature that may be exploited for therapeutic targeting in age-related vascular diseases.