Targeting cellular senescence in dermatology: senolytic and senomorphic strategies.

Abstract

Cellular senescence has emerged as a central mechanism driving cutaneous aging, impaired regeneration, and numerous dermatologic pathologies. Initially evolved as a protective mechanism to prevent malignant transformation and facilitate wound repair, senescence becomes maladaptive when senescent cells persist. Senescent keratinocytes, fibroblasts, and melanocytes can secrete pro-inflammatory mediators and other factors, collectively termed the senescence-associated secretory phenotype (SASP), which may degrade extracellular matrix components, disrupt pigmentary balance, and impair barrier function. Senescent cells are resistant to conditions that cause death of non-senescent cells and are generally removed by the immune system. Persisting senescent cells can become increasingly pro-inflammatory and fibrotic, perhaps due to accumulating DNA damage within these cells. Two primary geroscience-based therapeutic paradigms (gerotherapeutics) have been proposed: senolytics, which selectively eliminate senescent cells, and senomorphics, which modulate or suppress SASP activity without inducing senescent cell death. In dermatology, these approaches are particularly relevant given skin's accessibility, visible aging markers, and ability to serve as a translational platform for systemic gerotherapeutic interventions. Interfering with the development of senescent cells, for example by interfering with such regulators of senescent cell formation as p16, retinoblastoma protein (pRB), p53, or p21, can be detrimental due to the protective roles of transient senescence in wound healing and cancer suppression. However, senolytics, which do not prevent senescent cells from developing but rather act by clearing already formed persisting and tissue-damaging senescent cells, offer the potential to delay, prevent, alleviate, or treat aged or fibrotic skin. Because of the days to weeks for senescent cells to form fully and their inability to divide, senolytics can be administered intermittently, for example for brief intervals every 2 weeks or once a month. Senomorphics, conversely, can modulate the detrimental effects of the SASP and generally need to be administered continuously or more frequently than senolytics. Some agents are both senolytic and senomorphic. This review considers the mechanistic underpinnings of senescence in skin, the evidence for both therapeutic approaches, and the future directions for integrating senotherapeutics into regenerative and aesthetic dermatology. Advances in cutaneous biomarkers, topical delivery systems, and AI-assisted patient stratification are expected to accelerate translation into clinical practice.