Parkinson's disease (PD) is characterized by progressive dopaminergic cell loss in the substantia nigra (SN) and elevated
iron levels demonstrated by autopsy. Direct visualization of
iron with live imaging techniques has not yet been successful. The aim of this study is to visualize and quantify the distribution of cellular
iron using an intrinsic
iron hyperspectral fluorescence signal. The
1-methyl-4-phenylpyridinium (MPP+)-induced cellular model of PD was established in SHSY5Y cells exposed to
iron with
ferric ammonium citrate (FAC, 100 μM). The hyperspectral fluorescence signal of
iron was examined using a high-resolution dark-field optical microscope system with signal absorption for the visible/near infrared spectral range. The 6-h group showed heavy cellular
iron deposition compared with the 1-h group. The cellular
iron was dispersed in a small particulate form, whereas the extracellular
iron was aggregated. In addition,
iron particles were found to be concentrated on the cell membrane/edge of shrunken cells. The
iron accumulation readily occurred in MPP+-induced cells, which is consistent with previous studies demonstrating elevated
iron levels in the SN. This direct
iron imaging could be applied to analyze the physiological role of
iron, and its application might be expanded to various
neurological disorders involving metals, such as
copper,
manganese, or
zinc.