TL;DR
Overall, aging outcomes reflect a dynamic equilibrium between damage and repair processes, and how this balance is modulated in long-lived individuals may inform strategies to promote healthy aging and delay the onset of age-related diseases.
The frequent conceptual overlap between aging and cellular senescence has generated ambiguities in experimental approaches, biomarker usage, and therapeutic strategy development within aging research. Cellular senescence and aging are biologically distinct but interconnected processes, frequently misunderstood or used interchangeably within biomedical research and theoretical discussions. Thus, aging refers to the progressive decline in physiological integrity and function at the organismal level, while cellular senescence is a stable cell-cycle arrest triggered by various forms of stress, including DNA damage, telomere shortening, epigenetic dysregulation, and mitochondrial dysfunction. This review dissects the molecular underpinnings of both phenomena, highlighting their key differences, mechanistic overlaps, and roles in health and disease, with particular emphasis on how the accumulation of senescent cells actively contributes to age-related functional decline. In particular, we discuss emerging biomarkers and therapeutic strategies, such as senolytics and partial reprogramming. Furthermore, a deeper understanding of these processes may contribute to the identification of innovative interventions for age-related disorders, such as therapies targeting specific components of the senescence-associated secretory phenotype or selectively modulating senescent cell burden.
The capacity for tissue repair and regeneration undergoes a profound and progressive decline across the human lifespan, representing a fundamental driver of aging and chronic disease. This review establishes a comprehensive ontogenetic framework by mapping the continuous biological transition from the flawless, scarless regenerative plasticity of embryonic development to the irreversible fibrotic scarring and organ failure characteristic of senescence. We synthesize the hierarchical collapse of reparative networks across multiple biological scales. Importantly, this ontogenetic decline should not be interpreted as a purely degenerative trajectory but rather as a dynamic systems-level reprogramming in which evolutionary trade-offs prioritize tumor suppression, immune surveillance, and reproductive fitness over long-term regenerative fidelity. Recognizing this adaptive reallocation of biological resources reframes aging not simply as failure but as a predictable recalibration of repair hierarchies. At the molecular and cellular levels, the accumulation of genomic instability, unresolvable DNA damage, and mitochondrial dysfunction gradually overwhelms intracellular quality-control mechanisms. Concurrently, epigenetic drift and chronic, low-grade systemic inflammation ("inflammaging") dismantle the stem cell niche, driving adult stem cell exhaustion and shifting wound healing away from functional tissue replacement toward maladaptive fibrosis. Furthermore, we examine divergent, organ-specific repair trajectories. By contrasting the severe regenerative restrictions of the adult central nervous system and myocardium with the persistent, yet exhaustible, resilience of the liver, we elucidate the unique intrinsic and microenvironmental barriers that impede structural and functional recovery. Finally, we evaluate the clinical paradigm shift from passive management of age-related degeneration to active restoration of tissue integrity. By integrating systemic geroscience-which addresses the global hallmarks of aging-with targeted bioengineering and in vivo epigenetic modulation, contemporary regenerative medicine seeks to recreate permissive, youthful microenvironments. Ultimately, mastering these ontogenetic principles holds unprecedented potential to reactivate endogenous repair pathways, mitigate multi-organ collapse, and significantly extend human functional healthspan.
Biological aging is a gradual, multisystem process characterized by progressive functional decline, diminished physiological resilience, and increased susceptibility to chronic diseases. Growing evidence suggests that persistent exposure to adverse social environments, chronic psychological stress, and socioeconomic disadvantage can accelerate biological aging by altering age-related biomarkers and stress-response pathways. The weathering hypothesis provides a framework to explain how the cumulative burden of psychosocial adversity becomes biologically embedded, resulting in physiological wear and tear that hastens age-related deterioration over time. A central mechanism underlying this process is chronic low-grade inflammation, which contributes to the pathogenesis of numerous age-related conditions, including cancer and neurodegenerative diseases (NDDs). These disorders are highly prevalent among Caribbean Hispanics, a population disproportionately affected by social disadvantages and rapid population aging. Recent advances in the biology of inflammation and cellular senescence have generated interest in therapeutic strategies aimed at modulating fundamental mechanisms of aging. Emerging approaches, including senolytics, anti-inflammatory agents, and non-coding RNA–based interventions, offer promising opportunities for precision medicine; however, RNA-based therapies remain largely experimental, and their clinical translation to address stress-related aging and health disparities has yet to be established. In this review, we examine the interplay between weathering and inflammation in shaping biological aging and discuss the potential of innovative precision medicine approaches to mitigate age-related decline and reduce health disparities in vulnerable populations.
Aging is characterized by a progressive decline in physiological resilience and increased susceptibility to chronic diseases, including neurodegenerative disorders. Emerging evidence indicates that low-dose stressors (collectively termed hormetic stimuli) activate adaptive cellular responses that enhance stress resistance, promote repair mechanisms, and ultimately extend healthspan. This narrative review synthesizes current knowledge on hormesis in the context of aging, with a focus on key molecular pathways including nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuins, autophagy, and mitohormesis. We examine how lifestyle interventions (physical exercise, caloric restriction, mild thermal stress) and emerging pharmacological agents induce beneficial adaptive responses, while critically evaluating their translational potential in clinical and public health settings. Special emphasis is placed on the role of hormesis in counteracting neurodegeneration, the utility of autophagy and systemic aging biomarkers (epigenetic clocks, inflammaging scores) for precision dosing, and the limitations imposed by inter-individual variability, age-related decline in adaptive capacity, and risks of overexposure. Importantly, this review distinguishes experimentally demonstrated hormetic responses from broader adaptive stress responses and critically evaluates situations in which hormetic mechanisms may be insufficient, maladaptive, or clinically inappropriate. Understanding the delicate balance between beneficial and detrimental stress responses is essential for leveraging hormesis as a robust strategy to counteract aging and age-related diseases. We further propose a multilevel framework integrating molecular mechanisms with clinical outcomes, positioning hormesis as a key determinant of adaptive resilience (stress resistance, mitochondrial function, HRV, VO2max) in aging.
The evolutionary theory of aging demonstrates that the force of natural selection declines with age in multicellular organisms. Two population genetic mechanisms are consistent with the evolutionary theory: mutation accumulation and antagonistic pleiotropy. These in turn account for the physiological, cellular, and molecular mechanisms associated with aging. Spaceflight provides an opportunity to examine how organisms physiologically acclimate to environmental conditions. Mitochondria and the gut microbiome are central regulators of host metabolism, redox homeostasis, immune function, and physiological resilience, and both are impacted by host adaptations and acclimations. Mitochondrial dysfunction and oxidative stress have consequently emerged as important candidate mechanisms linking biological aging and spaceflight-associated physiological change. This review examines evidence surrounding mitochondrial dysfunction, oxidative stress, and gut microbiome dysbiosis across humans, mice, and fruit flies under spaceflight and corresponding terrestrial control conditions. This review reports further on the progression of theory and recent evidence from spaceflight missions for how biomarker genes most associated with mutation accumulation and antagonistic pleiotropy appear to have a core role in natural aging and extreme physiological acclimation.
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