Quantitative biomarkers of human skin photoaging based on intrinsic second harmonic generation signal

Collagen change is a major feature in the photoaged human skin. Here, we present the use of intrinsic second harmonic generation (SHG) signal as a novel means to quantify collagen change with photoaging. We obtain the SHG images of the superficial dermis from ex vivo the cheek skin and the abdomen skin of eight patients aged 55-60 years. The results show that SHG signal can quantitatively reveal collagen change between normal and photoaged human skin in three dimensions. By comparing normal with photoaged dermis, there are significant differences in the collagen content and fine structure, providing substantial potential to be applied in vivo for the clinical diagnosis of human skin photoaging.