Abstract
Purpose: :
Proliferative conditions of the retina are major causes of visual impairment which involve choroidal endothelial and retinal pigment epithelium cells. We hypothesize that proliferation of these cells produce factors that changes the intraocular environment in a way which is conducive for proliferation of other cells types, creating a vicious cycle.
Methods: :
To identify this relationship, the cell lines representative of choroidal endothelial cells (RF6A), retinal pigment epithelium cells (ARPE-19) and retinal ganglion cells (RGC-5) were cultured in serum and serum free conditions. Conditioned media was collected and used to supplement the growth media in increasing concentration (0, 25, 50, 75 and 100%) of other cell types. The conditioned media from RGC-5 was used to assess stimulatory effect on ARPE-19 and RF6A; from RF6A on RGC-5 and ARPE-19 and from ARPE-19 on RGC-5 and RF6A. Cell proliferation was assessed by WST-1 assay. To characterize the secreted factors, the conditioned media was heat inactivated by heating at 56 degrees for 45 min before use. In limited experiments (ARPE-19 conditioned media on RF6A cells), conditioned media was heat inactivated by boiling or was treated with anti-vascular endothelial growth factor (VEGF) monoclonal antibodies (bevacizumab).
Results: :
The conditioned media from all the cell types stimulated the proliferation of cells tested. This stimulatory effect was neutralized/partly neutralized by heat-inactivation.
Conclusions: :
Our results demonstrate that proliferation of retinotypic cells produce factors that can significantly alter the intraocular environment, such that it favors cell proliferation thus establishing a vicious cycle. Breaking this cycle may provide an opportunity to modulate the course of proliferative vitreo-retinal conditions.
Keywords: proliferation • protein purification and characterization • retina