Abstract
Purpose: :
Basement membranes (BMs) are considered to be uniform extracellular matrix sheets of less than 100nm that serve as a substrate for epithelial cells, endothelial cells and myotubes. To find out whether ocular BMs undergo age and diabetes-dependent alterations the inner limiting membranes (ILM), the retinal vascular BMs, Descemet’s membrane and the lens capsule from humans of different ages were investigated.
Methods: :
BMs were isolated from 22 to 89-year-old eyes obtained from the Center of Organ Recovery and Education, Pittsburgh. The BMs were investigated by Transmission electron microscopy (TEM), Atomic Force Microscopy (AFM) and by SDS PAGE, Western blots and Mass spectrometry.
Results: :
TEM showed that the ILM steadily increases in thickness from 70nm at fetal stages to several microns at age 90. This increase in thickness is significantly greater after 5 to 10 years of insulin-dependent and non-insulin dependent diabetes. AFM showed that ILMs become increasingly stiffer with older age. The morphological changes are accompanied by age-related changes in the biochemical composition, whereby the relative concentrations of collagen IV and agrin increase, and the concentration of laminin decreases with age.
Conclusions: :
We propose that the age and diabetes-related changes in the ocular BMs contribute to the higher incidence of disease at old age and to the pathology of diabetic retinopathy.
Keywords: aging • diabetes • retina