Evaluation of UV radiation-induced toxicity and biophysical changes in various skin cells with photo-shielding molecules

Ultraviolet radiation (UVR) triggers many complex events in different types of skin cells, including benign, malignant and normal cells. Chromophores present in these cells play a crucial role in various cellular processes. Unprecedented methods are required for the real-time monitoring of changes in an in vitro model exposed to intermittent mild and intense UVR to determine the mechanisms underlying cell degeneration and the effects of unexpected toxic, agonist and antagonist agents. This study reports the analytical application of a whole cell-based sensor platform for examining the biophysical effects of UVR. We used human keratinocyte, melanocyte and fibroblast cell lines to determine the normal, pathological and protective roles of UVR. In addition, we examined the real-time morphological, biophysical and bio-mechanical changes associated with cell degeneration induced by UVR at 254 and 365 nm. Information on UVR-induced changes in the cytoskeleton ultrastructure, cellular integrity, cell spreading area, actin microfilament distribution inflammation, microtubule damage, membrane damage, rupture and death was characterized by examining the loss or increase in biophysical and biomechanical properties of these cells. All cells exposed to UVR at 254 and 365 nm showed a significant increase in surface roughness and stiffness in a time-dependent manner. UVR-induced toxicity in differently pigmented skin cells was compared with that in cells pretreated with melanin, keratin and basic fibroblast growth factor to analyze the shielding efficiency of these agents. Melanin exerted a significant shielding effect compared to the other two agents. The biophysical and biomechanical information obtained in this study could advance our understanding of the UVR-induced degeneration process, and help in developing new interventions strategies.