Accumulation of cholesterol with age in human Bruch's membrane

PURPOSE. To determine the cholesterol composition of normal human Bruch's m embrane and choroid as a function of age and retinal location. METHODS. Human eyes with grossly normal maculas were preserved <4 hours aft er donor death. Cryosections of retina and choroid from the macula and temp oral equator were stained with filipin to reveal esterified (EC) or unester ified (UC) cholesterol (n = 20, 17-92 years). Filipin fluorescence in Bruch 's membrane was quantified with digital microscopy. Maculas were prepared f or lipid-preserving electron microscopy (n = 18, 16-87 years) and for ultra structural analysis after lipid extraction (n = 2, 85 and 89 years). Punche s of macular Bruch's membrane, 8 mm in diameter, were assayed for cholester ol content by enzymatic fluorometry (n = 10, >70 years). RESULTS. EC and UC in Bruch's membrane increased with age in the macula. EC was sevenfold higher in macula than in periphery. Sixty percent of total c holesterol was esterified, and Bruch's membrane EC was 16- to 40-fold enric hed relative to plasma. Solid, 100-nm-diameter particles occupied >30% of t he inner collagenous layer in eyes >60 years. Cholesterol accumulated in ch oroidal arteries and in small age-related drusen. CONCLUSIONS. Human Bruch's membrane ages like arterial intima and other con nective tissues for which plasma lipoproteins are the known source of extra cellular cholesterol. Age-related maculopathy and atherosclerotic cardiovas cular disease may share common pathogenic mechanisms.