Overexpression of klotho in adipose-derived stem cells protects against UVB-induced photoaging in co-cultured human fibroblasts

Co-culture methods are widely used in tissue engineering to drive tissue formation with the direct or indirect interaction of multiple cell types. Klotho is a novel biomarker involved in aging. In this study, we evaluated the protective effects of klotho overexpressed adipose-derived stem cells (ADSCs) against ultraviolet radiation B (UVB)-induced photoaging in co-cultured human skin fibroblasts (HSF2 cell line). Furthermore, the involvement of P38 mitogen-activated protein kinase (MAPK) signaling was investigated. ADSCs were isolated from human subcutaneous adipose tissue and the 3rd generation of ADSCs was used after being identified. Klotho overexpression (OE) lentivirus vectors were constructed and identified in ADSCs. The HSF2 cells were seeded in the upper layer of the Transwell co-culture plate (0.4 µm pore polycarbonate membrane) and ADSCs were seeded in the lower layer. UVB irradiation of HSF2 cells was performed using UVB lamps in uncovered petri dishes at room temperature. The present results indicated that the proliferation of ADSCs was increased by klotho OE. Furthermore the proliferation and collagen content of HSF2 were decreased by UVB irradiation in a dose-dependent manner. By contrast, the protein level of matrix metalloproteinases (MMP) 1, 3 and p-P38 in HSF2 were upregulated. In the co-culture system, relative mRNA expression of MMP-1 and MMP-3 as well as protein level of MMP-1, MMP-3 and p-P38 in HSF2 were reduced by co-culture with klotho overexpressed ADSCs when exposed to UVB (20 mJ/cm2). By contrast, the collagen content of HSF2 was increased. Collectively, OE of klotho in ADSCs notably ameliorates UVB-induced photoaging in co-cultured HSF2, and these effects were potentially achieved by increasing the collagen content and decreasing the protein level of MMP-1, MMP-3 and p-P38.