Abstract
Purpose: :
We have shown recently that zinc is abundantly enriched in the presence of several trace metal in sub-RPE deposits in humans. In our present study, we aimed to determine the co-distribution and concentration of copper, iron, calcium and several other trace metals, and compare these to zinc, in both peripheral and macular sub-RPE deposits from human donor eyes.
Methods: :
Donor eyes used in the study were obtained by the Eye Bank at Moorfields Eye Hospital less than 24 hours post mortem. Areas with sub-RPE deposists from regions of the macula, equator and far peripheryal and central retinae were dissected. Following the removal of the neuronal retina, the retinal pigment epitheliumal cells and most of the choroid, the remaining choroidal microcapillaries/Bruch’s membrane/sub-RPE deposit complex was flat mounted. These were analyzed by microprobe synchrotron X-ray fluorescence (µSXRF) at the X27A beam line at the National Synchrotron Light Source at Brookhaven National Laboratory. For some measurements deposits were isolated and sectioned.
Results: :
We identified the presence of several trace elements in sub-RPE deposits, as well as Bruch’s membrane, both at the periphery and in the macula. The most consistently concentrated trace metal was zinc. Many but not all sub-RPE deposits contained iron, calcium, copper, and other trace metals.
Conclusions: :
Zinc, iron, copper, calcium and several other trace elements, such as nickel, are present in sub-RPE deposits but only zinc is present in all deposits. Given the role zinc plays in complement factor H regulation, our results may, suggest that other trace metals could may their accumulation could also play a role in the molecular events leading to sub-RPE deposist formation and the development and/or progression of AMD. The exact role and the mechchanism for trace element metal accumulation in the disease process, however, is yet to be determined.
Keywords: age-related macular degeneration • calcium