Fisetin Reverses Chemo-Induced Vascular Aging by Clearing Senescent Cells

**Why this matters:** Cardiovascular disease is a leading cause of death among cancer survivors, and doxorubicin—one of the most widely used chemotherapy agents—is a potent driver of premature vascular aging. Excess cellular senescence triggered by doxorubicin floods the vascular microenvironment with pro-inflammatory cytokines (the SASP), which elevates mitochondrial reactive oxygen species (ROS), depletes vasodilatory nitric oxide (NO), and ultimately causes endothelial dysfunction and arterial stiffening. Identifying safe, orally available compounds that can clear these senescent cells after chemotherapy is a major unmet clinical need.

**What was studied:** The research team used a three-pronged approach: (1) human aortic endothelial cells (HAECs) exposed to 200 nM doxorubicin for 24 hours, then treated with escalating fisetin doses (0.25–1.0 µM); (2) young adult (4–6 month) p16-3MR transgenic mice given a single intraperitoneal doxorubicin injection (10 mg/kg), then randomized to oral intermittent fisetin (100 mg/kg/day) or vehicle using a 1-week-on / 2-weeks-off / 1-week-on schedule; and (3) ex vivo isolated aortic ring and plasma SASP analyses to dissect circulating versus local senescence contributions. Four groups were studied in vivo: Sham-Vehicle (n=13), Sham-Fisetin (n=12), Doxo-Vehicle (n=11), and Doxo-Fisetin (n=14). Animals were sacrificed 1–2 weeks after the final fisetin dose to exclude acute pharmacological effects.

**Key results:** In vitro, doxorubicin increased SA-β-galactosidase signal by ~80% and drove 5–10-fold upregulation of senescence genes (Cdkn2a, Cdkn1a, Serpine1) while suppressing Lmnb1. Treatment with 1.0 µM fisetin reversed these changes by ~50–80%. In vivo, doxorubicin-vehicle mice showed significantly impaired endothelium-dependent dilation (EDD) and elevated aortic pulse wave velocity (PWV) versus sham controls. Fisetin fully reversed both deficits (p<0.001 for each). Mechanistically, fisetin reduced aortic senescent cell markers (p16, p21, SA-β-gal), suppressed circulating SASP cytokines in plasma, restored NO bioavailability, and lowered mitochondrial superoxide production in endothelial cells. Doxo-fisetin mice also showed reduced frailty scores versus doxo-vehicle mice, suggesting broader systemic benefit.

**Implications:** These findings establish oral intermittent fisetin supplementation as a mechanistically coherent and effective strategy to counteract doxorubicin-induced premature vascular aging. The dosing regimen (100 mg/kg/day in mice equating to ~1 µM peak plasma fisetin) is pharmacologically achievable and mirrors doses already being tested in human clinical trials for aging-related conditions. The dual benefit of clearing local vascular senescent cells and modulating the systemic SASP suggests fisetin may protect multiple organ systems beyond the vasculature in chemotherapy survivors.

**Caveats:** The study was conducted exclusively in young adult male and female mice and HAECs; translation to older cancer patients or those with comorbidities requires further study. The p16-3MR mouse model is a specialized transgenic line, and results may not fully generalize to wildtype animals or humans. Long-term safety and efficacy of repeated fisetin dosing post-chemotherapy remain to be established in clinical trials.