Effects of Repeated UVA Irradiation on Human Skin Fibroblasts Embedded in 3D Tense Collagen Matrix. (31st March 2018) - Nakyai, Wongnapa
Abstract: Skin photoaging is caused by cumulative UVA exposure that leads to dermal matrix alterations associated with impaired fibroblast functions. In this study, we evaluated the effects of repeated UVA irradiation on mechanically stressed fibroblasts which were embedded in 3D tense collagen matrix. By comparison to 2D monolayer culture, we investigated the expressions of alpha‐smooth muscle actin ( α ‐SMA) cytoskeleton and α 2 subunit of integrin receptors, as well as the collagen metabolism, focusing to MMP‐1 and collagen type‐I expressions. We found that UVA exposure reduces collagen levels in both culture conditions. However, concerning integrin α 2 and α ‐SMA expression, UVA irradiation had no effect on 2D culture, whereas in tense 3D culture, it had an inhibitory effect. In UVA‐irradiated 3D culture, fibroblasts acquired elongated shape and lost their dynamic interaction with collagen fibers through a decrease in integrin α 2 and α ‐SMA. Fibroblast responses to UVA irradiation were different in 2D versus 3D environment, highlighting the importance of collagen environment in the regulation of mechanical activities. The behavior of fibroblast upon mechanical stimulation closely mimics stressed extracellular environment. The model of UVA‐irradiated fibroblasts cultured in tense 3D collagen gel illustrated the in vivo situation of both mechanically stressed and photoaged human skin. Abstract : In non‐UVA irradiated fibroblasts, the expressions of type I procollagen, MMP‐1, α‐SMA and integrin α2 were up‐regulated in 3D as compared with 2D. UVA exposure reduced type I procollagen levels and increased MMP‐1 levels in both culture conditions. Fibroblasts cultured in 3D and repeatedly irradiated with UVA exhibited decrease in a‐SMA and integrin α2 expressions whereas such decrease was not observed in 2D cultured cells with repeated UVA irradiation.