Multimodal approach to reveal the effect of light irradiation on chemical composition of lipofuscin granules of human RPE tissues

Abstract

The accumulation of lipofuscin (LF) in tissues is considered as one a hallmark of the aging process. Usually formed in yellow-brown pigment aggregates or granules primarily composed of lipid residues and proteins, the exact chemical composition of LF varies among tissues. LF of the retinal pigment epithelium (RPE) is known to contain byproducts of the visual cycle, including one of the fluorophores in LF bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E). The last is characterized by high photoreactivity and implicates in age-related macular degeneration. Photoinduced production of reactive oxygen species (ROS) is shown among the main modes of A2E toxicity although particular photochemistry of A2E have yet to be completely identified. In this work we study changes in chemical composition of LF granules of human RPE under light irradiation using vibrational spectroscopy (femtosecond broadband CARS) and mass-spectrometry (TOF-SIMS) approach accompanied by measurements of fluorescence properties of the LF.