Intermittent supplementation with fisetin improves arterial function in old mice by decreasing cellular senescence

#1

Cellular senescence and the senescence-associated secretory phenotype (SASP) contribute to age-related arterial dysfunction, in part, by promoting oxidative stress and inflammation, which reduce the bioavailability of the vasodilatory molecule nitric oxide (NO). In the present study, we assessed the efficacy of fisetin, a natural compound, as a senolytic to reduce vascular cell senescence and SASP factors and improve arterial function in old mice. We found that fisetin decreased cellular senescence in human endothelial cell culture. In old mice, vascular cell senescence and SASP-related inflammation were lower 1 week after the final dose of oral intermittent (1 week on—2 weeks off—1 weeks on dosing) fisetin supplementation. Old fisetin-supplemented mice had higher endothelial function. Leveraging old p16-3MR mice, a transgenic model allowing genetic clearance of p16INK4A-positive senescent cells, we found that ex vivo removal of senescent cells from arteries isolated from vehicle- but not fisetin-treated mice increased endothelium-dependent dilation, demonstrating that fisetin improved endothelial function through senolysis. Enhanced endothelial function with fisetin was mediated by increased NO bioavailability and reduced cellular- and mitochondrial-related oxidative stress. Arterial stiffness was lower in fisetin-treated mice. Ex vivo genetic senolysis in aorta rings from p16-3MR mice did not further reduce mechanical wall stiffness in fisetin-treated mice, demonstrating lower arterial stiffness after fisetin was due to senolysis. Lower arterial stiffness with fisetin was accompanied by favorable arterial wall remodeling. The findings from this study identify fisetin as promising therapy for clinical translation to target excess cell senescence to treat age-related arterial dysfunction.

Open Access Paper here: https://onlinelibrary.wiley.com/doi/10.1111/acel.14060

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#2

Have you dug into explanations of why there were no tissue differences in the ITP samples, when other groups keep publishing results like this, yet?

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#3

This was my question as well. Rich Miller has been very skeptical of senolytics and fisetin in particular due to ITPs inability to get Fisetin to do much of anything at all and questioning even the definition of a senescent cell as a single concept (saying that there are many ways an aged cell can go wrong). But then other labs seem to be using fisetin successfully and seeing statistically significant changes.

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#4

Am inspecting the charts. I see fisetin for 2018, but no fisetin for 2019. The 2018 charts show fisetin (fis) lifespan at about 1200 days.

#5

Some of the same authors have a new paper out:

Fisetin Supplementation Attenuates Premature Vascular Aging Induced by Doxorubicin via Suppression of Cellular Senescence and Mitochondrial Oxidative Stress

Abstract

The genotoxic agent doxorubicin induces premature vascular aging, defined by vascular endothelial dysfunction and aortic stiffening. Excess vascular cell senescence and the accompanying senescence-associated secretory phenotype (SASP) are key mechanisms underlying doxorubicin-induced vascular dysfunction, in part, by promoting excess mitochondrial oxidative stress, which reduces the bioavailability of the vasodilatory molecule nitric oxide (NO). In the present study, we assessed if the natural senolytic fisetin mitigates doxorubicin-induced cellular senescence and the SASP to improve vascular function following doxorubicin administration and explored the underlying mechanisms. Young adult (6 months) mice were treated with doxorubicin, followed by oral, intermittent fisetin supplementation (100 mg/kg/day; 1 week on treatment-2 weeks off treatment-1 week on treatment). Vascular endothelial function, aortic stiffness, cellular senescence markers, SASP expression, NO bioavailability, and mitochondrial oxidative stress were assessed. Parallel experiments in human aortic endothelial cells were conducted to provide further mechanistic insight. Fisetin mitigated excess vascular cell senescence and the SASP in young mice administered doxorubicin and reversed doxorubicin-induced endothelial dysfunction (p < 0.001) and aortic stiffening (p < 0.001), in part through suppression of excess cellular senescence, higher NO bioavailability, and lower mitochondrial oxidative stress. Modulation of the circulating SASP (plasma) also contributed to the observed vascular improvements with fisetin. In vitro, fisetin reduced cellular senescence in doxorubicin-exposed endothelial cells, supporting isolated artery and in vivo observations. These findings identify oral intermittent fisetin supplementation as a promising therapeutic strategy for targeting excess cellular senescence to improve vascular function in settings of premature vascular aging.

#6

I know you asked this question more than 2.5 years ago, but since the thread is bumped, I’ll give my opinion (as a professor, and researcher running my own lab).

Personally, I think it’s because there is experimenter bias and publication bias, plus some effects of what specific animal model is chosen. I won’t say the authors just make up the results, but there is certainly a bias towards publishing your successes, and you don’t know how many failures were buried, how many “outlier” results were excluded etc.

Experimenter bias is a huge factor, and most labs don’t do rigorous blinding etc. When Rich Miller sent the samples back to the lab that suggested Fisetin, he sent them blinded, so they didn’t know what groups they were measuring. Even across multiple “senescence” markers (p16ink, p21 etc), there were no differences after the unblinding.

These single-lab studies report positive results in a single/special mouse strain, but a larger, unbiased replication study across multiple labs using heterogenous mice fails. This happens all the time in science, where a molecule looks goo din the lab but fails at the clinical trial. IMO, you have to think realistically and prioritise the highest quality evidence, which is obviously the ITP.

Now the new study just shared is really interesting. They call it “vascular aging” but I would say that’s a bit of a sales pitch term. This isn’t an aging study really. They’re using Doxorubicin, a toxic chemotherapy agent, to induce injury. That is a real problem clinically, and oncologists limit use of Dox in order to avoid cardiac toxicity. There are even clinical trials of drugs (including Fisetin) in cancer patients to see whether it can mitigate some of that toxicity. So this is very interesting and pretty important, but isn’t really related to anti-aging.

I can’t explain why they see the decrease in cdkn2a cdk21a etc (that’s your p16/21) with Fisetin when the ITP didn’t find it. However, I don’t see anywhere where they actually showed the fisetin killing senescent cells. Fisetin is a pretty non-specific dirty/promiscuous molecule, inhibiting kinase enzymes, inhibiting NF-kB, having some antioxidant functions. So maybe other things are at play.

I asked Claude to compare the dose regimen between ITP and this study. ITP obviously uses steady-state delivery for a long time, whereas this study used a high dose in short intervals. Claude raised an interesting point that the Dox-induced senescence may not be the same thing as chronological aging-induced senescence (I believe Rich Miller himself has said this). And, it also mentioned that Fisetin may work prophylactically (preventing or short-circuiting senescence induction) rather than senolytically (killing established senescent cells) in this Dox model. They gave fisetin 1 week after Dox, so cells are stimulated/pushed towards senescence by the Dox, but aren’t fully committed yet.

Very interesting though, and certainly revives a bit of my interest in Fisetin. Perhaps not for preventing aging/senescence, but it at least shows some pretty clear benefits in this acute toxicity model.

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