Fisetin Supplementation Improves Age‐Related Vascular Endothelial Function by Suppressing Cellular Senescence and Mitochondrial Oxidative Stress
Authors: Mahoney Sophia A. , Venkatasubramanian Ravinandan , Rossman Matthew , VanDongen Nicholas , Brunt Vienna , Casso Abigail , Greenberg Nathan , Melov Simon , Campisi Judith , Seals Douglas , Clayton Zachary 
Published: May 2022

Age‐related vascular endothelial dysfunction is mediated by excess reactive oxygen species (ROS)—mitochondria (mito) being a key source—which can reduce nitric oxide (NO) bioavailability. Cellular senescence, a fundamental mechanism of aging, may exacerbate mito ROS and be a potential therapeutic target to combat age‐related vascular dysfunction.

Purpose

To determine if treatment with the natural flavonoid fisetin improves endothelial function with aging by suppressing cellular senescence, scavenging excess whole‐cell and mito ROS, and increasing NO bioavailability.

Methods & Results

Old (27 mo) male C57BL/6 mice were treated with vehicle (V; 10% EtOH, 30% PEG400 and 60% Phosal 50 PG; n = 9) or fisetin (Fis; 50 mg/kg/day in V; n = 10) by oral gavage following a 1 wk on – 2 wk off – 1 wk on dosing paradigm.

Endothelial function

Endothelial function was assessed by ex vivo carotid artery endothelium‐dependent dilation (EDD) and endothelium‐independent dilation (EID) to increasing doses of acetylcholine and sodium nitroprusside, respectively. EDD was greater in Fis vs V treated mice (Peak EDD [%]: 97 ± 1 vs 84 ± 3, P < .05) and no differences were observed among groups in EID (P = .54).

Cellular senescence

Fis‐treated mice had lower vascular abundance of p16, an established marker of cellular senescence (Fis, .12 ± .01 vs V, .19 ± .02 chemiluminescence units [CU], P < .05). Next, we administered Fis or V to old (27 mo) p16‐3MR mice (a model that allows for clearance of senescent cells with ganciclovir [GCV]; n = 6/group). Fis‐treated p16‐3MR mice had greater EDD (Peak EDD [%]: Fis, 93 ± 2 vs V, 74 ± 5, P < .05). Ex vivo carotid artery incubations with GCV eliminated group differences in EDD, suggesting that Fis reduced senescent cells to improve EDD.

Whole‐cell ROS

Electron paramagnetic resonance (EPR) spectroscopy was used to assess whole‐cell vascular (aortic) ROS. Fis‐treated mice had lower whole‐cell ROS (Fis, 4703 ± 455 vs V, 8173 ± 1243 amplitude units [AU], P < .05). Incubation with the ROS scavenger TEMPOL eliminated group differences in EDD, implying that Fis ameliorated ROS‐related suppression of EDD.

Mito ROS

EPR was used to assess vascular mito ROS. Fis‐treated mice had lower mito ROS (Fis, 2527 ±440 vs V, 6603 ± 1956 AU, P < .05). Further, Fis‐treated mice had lower abundance of vascular p‐p66SHC, a recognized marker of mito oxidative stress (Fis, .029 ± .003 vs V, .049 ± .008 CU, P < .05) and greater abundance of Mn superoxide dismutase, a mito antioxidant enzyme (Fis, .41 ± .1 vs V, .20 ± .02 CU, P < .05). Incubation with the mito‐specific antioxidant, MitoQ, eliminated group differences in EDD, implying that Fis ameliorated mito ROS‐related suppression of EDD.

NO

Addition of the NO‐synthase inhibitor, L‐NAME, abolished group differences in EDD suggesting Fis improved age‐related EDD impairments by increasing NO bioavailability.

Conclusion

Fisetin supplementation may be a novel strategy to target excess cellular senescence and thereby reduce mito ROS to improve NO‐mediated endothelial function with aging.