Abstract
Purpose: :
Endothelial cell (EC) migration and proliferation are key events in angiogenesis, and likely to play important roles in choroidal neovascularization in age-related macular degeneration (AMD). One potential stimulus in the choroidal microenvironment in eyes with AMD is the presence of elastin fragments. We previously observed that elastin fragments increase the migratory response of choroidal endothelial cells. In this study we sought to evaluate whether elastin fragments promote EC proliferation in vitro, as well as determine whether choroidal endothelial cells express the elastin binding protein (EBP), which is an alternatively spliced form of beta galactosidase (GLB1).
Methods: :
The chorioretinal EC line RF/6A was cultured in the presence of medium containing elastin bioactive hexapeptides (BPs), EDPs, kappa elastin, or balanced salt solution (control) for 72 hours. Cells were counted using a BD LSR flow cytometer and significance was determined using a Student’s t-test.RNA was isolated from human choroidal endothelial cells and assayed for the presence of GLB1 using isoform-specific RT-PCR.
Results: :
For RF/6A cells exposed to EDPs, kappa elastin, or BPs, the rate of proliferation did not significantly change in comparison to controls. Human choroidal ECs in culture were found to express the alternatively spliced mRNA that encodes the EBP.
Conclusions: :
Choroidal endothelial cells grown in culture express GLB1, an elastin binding protein that may elicit pro-angiogenic responses of these cells in response to elastin fragments. In contrast to their effects on endothelial cell migration, elastin fragments do not appear to increase or decrease proliferation. Pathologic neovascular membrane formation in AMD may therefore be due in part to elastin-mediated EC migration, whereas other stimuli are likely to be responsible for their proliferation.
Keywords: age-related macular degeneration • extracellular matrix • choroid: neovascularization