An In Vitro Model for Fibroblast Photoaging Comparing Single and Repeated UVA Irradiations

Abstract

The current method for efficient evaluation of antiphotoaging compounds is an in vitro skin culture model using a single ultraviolet A (UVA) irradiation of fibroblasts. However, skin photoaging is caused by repeated exposure to UVA radiation. The objective of this study was to develop an appropriate model for in vitro skin photoaging by comparing the different effects of single (5 J cm ) and repeated exposures (5 J cm × 3 times) of fibroblasts to UVA irradiation. Our results demonstrated that a single and repeated exposure to UVA irradiation had different effects on fibroblasts. In the single UVA-irradiated group, collagen lattice contraction and the protein levels of type I procollagen and matrix metalloproteinase-1 (MMP-1) increased, while the levels of fibronectin and alpha-smooth muscle actin (α-SMA) were unchanged, compared to levels in the non-UVA-irradiated group (control). In contrast, repeated UVA exposure significantly induced G0/G1 cell cycle arrest, reduced collagen lattice contraction and type I procollagen and fibronectin expression, and increased MMP-1 expression. There was no difference in α-SMA expression when comparing repeatedly irradiated and non-UVA-irradiated fibroblasts. Our findings clearly indicate that repeated UVA irradiation of cells induces malfunctions found in photoaged skin and is an appropriate in vitro skin model of photoaging.

Effects of Repeated UVA Irradiation on Human Skin Fibroblasts Embedded in 3D Tense Collagen Matrix

“…We compared the expression of a-SMA in UVA-irradiated cells to non-UVA-irradiated cells. In monolayer, we confirmed the data of our previous study and showed that a-SMA expression does not change (25). In tense collagen lattice, we demonstrated that a-SMA expression in UVA-irradiated cells is lower than in non-UVA-irradiated cell.…”

“…Secondly, we reported effects of UVA radiation, and no difference of cell number in G2 phase was observed between irradiated and nonirradiated cultures, for both 2D and 3D models. In our previous work, repeated exposure to UVA (5 J cm À2 9 3 times) induced a decline in G2 phase cell number coupled with a damaged cell morphology (a smaller area of cytoplasm) (25). The discrepancy may result from the difference of cell culture conditions.…”

“…The UVA source was positioned at ~ 17 cm above the cell culture petri dish, emitting a UV intensity of 2.2 W cm −2 for 45 min (intensity of 6 J cm −2 ). The intensity of UVA used in this study was modified from the intensity used in our previous study (5 J cm −2 , ), according to the difference in UVA lamp source and culture condition. After UVA exposure, cells were maintained in DMEM supplemented with 10% FBS and antibiotics.…”

Gold Nanoparticles Using Ecklonia stolonifera Protect Human Dermal Fibroblasts from UVA-Induced Senescence through Inhibiting MMP-1 and MMP-3

“…Only 5% of solar radiation reaches the Earth's surface, comprising wavelengths in the ranges of 315-400 nm (ultraviolet A (UVA)), 280-315 nm (UVB), 100-280 nm (UVC). Specifically, UVA accounts for approximately 96.5% of the daily UV irradiation [1,2]. UVA irradiation can penetrate the epidermal and dermal layers of the skin, and contribute to oxidative stress, premature skin aging, and photo-carcinogenesis.…”

“…MMP-1 and MMP-3 are mainly secreted by HDFs, and degrade fibrillary collagen and type IV collagen. Studies on skin photoaging have shown that UVA promotes the degradation of ECM, as evidenced by a reduction in soluble collagen in the dermis that is associated with the upregulation of MMP-1 and MMP-3 [1,9].…”