Studying skin aging to better understand age-related physiological changes or to find novel molecules that could act on aging, could be relatively long and costly. Fish animal models could be particularly appropriated since skin structure has been shown remarkably useful to investigate pigment biology for example, in normal or tumoral cells (Schartl et al.,2016). In particular, the Japanese Medaka, a small fish model with attractive experimental characteristics, may accumulate over lifespan some biomarkers currently associated with aging features in other vertebrates. However, very few are known about aging of the medaka fish skin, especially in its biomechanical properties and skin architecture. In our study, we first confirmed that classical molecular changes occurred in Medaka skin during aging, as well as SA-β-galactosidase accumulation. Moreover, we performed for the first time measurements of Medaka skin stiffness by Atomic Force Microscopy (AFM) which revelated modulation of the bio-mechanical properties of the Medaka skin throughout life. Since a recent study showed a remodelling of the dermis matrix in aged mouse (Kaur et al., 2019), we thus investigated the correlation between skin stiffness and dermis aging in human skin reconstructs. Finally, we observed a modulation of collagen density in both human reconstructed and Medaka skins by Second Harmonic Generation (SHG) microscopy. Overall, our study unveiled the potential of Medaka fish to study skin aging and the AFM as an innovative technology to characterize this biological phenomenon.

Medaka fish as a good model to study skin aging by Atomic Force Microscopy