Abstract / Summary
Epidermal aging is characterized by progressive structural alterations, including reduced keratinocyte density, altered cellular morphology, and widened intercellular spacing (ICS). Reflectance confocal microscopy (RCM) combined with artificial intelligence (AI)-assisted image analysis enables non-invasive quantification of these changes in vivo. This secondary analysis of RCM images reported in a previously published randomized split-face clinical trial aimed to identify quantitative morphometric features associated with chronological aging and to evaluate their modulation following topical application of the transforming growth factor-beta (TGF-β) mimetic XEP™-716 Miniprotein™ (Activen SA, Lausanne. Switzerland). Previously acquired baseline RCM images from 49 women (age 40–60 years) were analyzed for associations with chronological age. Treatment effects were assessed in 25 women from the 2.5% arm of a 56-day randomized, double-blind, split-face study comparing XEP™-716 Miniprotein™ 2.5% with vehicle. AI-assisted image analysis quantified keratinocyte density, cellular circularity, and ICS in the stratum granulosum (SG) and the stratum spinosum (SS). Cells with circularity ≤ 0.439 were classified as low-circularity cells and those ≥ 0.440 circularity as morphologically normal. Treatment effects were assessed using linear mixed-effects models. Stratum granulosum total and normal keratinocyte densities were nominally significantly associated with age ( p = 0.015 and p = 0.023, respectively). Compared with vehicle, XEP™-716 Miniprotein™ used at 2.5% was associated with nominally significant increases in normal keratinocyte density ( p = 0.028) and the circularity of low-circularity cells ( p = 0.018), and with decreases in ICS thickness ( p = 0.030) and low-circularity cell density ( p = 0.044) in the SG. In the SS, there was a non-significant trend towards reduced low-circularity cell density ( p = 0.075). Artificial intelligence-assisted quantitative RCM can identify age-associated epidermal morphometric features, predominantly in the SG, and detect their modulation following topical treatment. XEP™-716 Miniprotein™ at 2.5% showed consistent treatment-associated changes across several morphometric parameters with nominal statistical significance. These exploratory findings warrant prospective validation against molecular senescence markers and functional barrier measurements.