Novel Strategy for Strengthening Dermatoporotic Skin by Managing Cellular Senescence.

Background: Dermatoporosis (DP) is a condition associated with thinning skin layers and resultant fragility. Much of the thinning is related to fibroblast dysfunction, production of destructive inflammatory cytokines, breakdown of the extracellular matrix (ECM), and weakening of the dermo-epidermal junction. A major contributor to this change in the ECM milieu, previously under-considered, is cellular senescence, particularly involving the papillary dermal fibroblasts.

Methods: A series of experiments were undertaken to explore the impact of a combination of known actives on senescent cell status. Human keratinocytes and fibroblasts were cultured, and cytotoxicity tests were performed to determine the ideal concentration to avoid cell toxicity. Microdoses of Centella asiatica (0.005%) and mandelic acid (0.05%) were found to be ideal in avoiding any cytotoxicity. However, the challenge was then to assess the efficacy of these actives in this microdosed form. After exposing the cells to the compounds, RNA was isolated and sequenced. Moreover, a well-described ex vivo model using photodamaged skin was subjected to immunofluorescence to identify senescent cells (via p16INK4a), particularly in the papillary dermis, using the microdose formulation compared to untreated skin. In addition, JAG/NOTCH expression in the epidermal basal cells was evaluated to further understand the cellular senescence signaling mechanism.

Results: Microdosing these two well-known agents had surprisingly significant synergistic effects in vitro, decreasing senescence-associated secretory phenotype (SASP) cytokines and the associated inflammation involved in the process. The ex vivo model revealed a significant (P<0.05) decrease in senescent cells in the papillary dermis and a significant increase (P<0.001) of JAG/NOTCH expression in the basal cells of the epidermis.

Conclusion: Using microdoses of two known agents, a novel approach produced an unexpected effect of reversal of dermal senescent cells and promoting an anti-inflammatory milieu. A gene expression analysis of the individual and combined actives validated these observations, followed by full formulation testing in an ex vivo model. The approach of limiting cellular senescence in dermal fibroblasts for managing DP is novel and provides an exciting new direction to address dermatoporosis. Clinical studies will follow. J Drugs Dermatol. 2024;23(9):748-756. doi:10.36849/JDD.8388.