Nanocarriers for natural polyphenol senotherapeutics

Senescence is a heterogenous and dynamic process in which various cell types undergo cell-cycle arrest due to cellular stressors. While senescence has been implicated in aging and many human pathologies, therapeutic interventions remain inadequate due to the absence of a comprehensive set of biomarkers in a context-dependent manner. Polyphenols have been investigated as senotherapeutics in both preclinical and clinical settings. However, their use is hindered by limited stability, toxicity, modest bioavailability, and often inadequate concentration at target sites. To address these limitations, nanocarriers such as polymer nanoparticles and lipid vesicles can be utilized to enhance the efficacy of senolytic polyphenols. Focusing on widely studied senolytic agents-specifically fisetin, quercetin, and resveratrol-we provide concise summaries of their physical and chemical properties, along with an overview of preclinical and clinical findings. We also highlight common signaling pathways and potential toxicities associated with these agents. Addressing challenges linked to nanocarriers, we present examples of senotherapeutic delivery to various cell types, both with and without nanocarriers. Finally, continued research and development of senolytic agents and nanocarriers are encouraged to reduce the undesirable effects of senescence on different cell types and organs. This review underscores the need for establishing reliable sets of senescence biomarkers that could assist in evaluating the effectiveness of current and future senotherapeutic candidates and nanocarriers.