Abstract
Purpose: :
The perivascular supporting cells, including pericytes (PC), are embedded within the vascular basement membrane of blood vessels, discontinuously contacting the vascular endothelial cells to maintain vessel stability and survival. The objective of this study was to establish Cyp1b1 expression in primary cultures of retinal PC and to demonstrate the impact of Cyp1b1-deficiency on retinal PC function.
Methods: :
Primary cultures of retinal PC were prepared from Cyp1b1+/+ and Cyp1b1-/- mice. The expression of various PC specific markers and Cyp1b1 was determined by FACScan and western blot analysis. Cell proliferation was determined by counting the number of cells and EdU DNA Click-it labeling. Cell viability in response to H2O2 was analyzed by MTS assay. The rate of apoptosis was measured by luminescent detection of caspase 3/7 activity under both basal and challenged conditions. The adhesion to the various extracellular matrix (ECM) proteins, production of various ECM proteins, and rates of migration were also determined.
Results: :
The Cyp1b1+/+ retinal PC constitutively expressed Cyp1B1, and Cyp1b1-/- retinal PC lacked expression, as expected. However, Cyp1b1+/+ and Cyp1b1-/- retinal PC expressed PC markers including NG2, PDGFR-beta, and smooth muscle actin, as well as desmin and calbindin. Cyp1b1-/- retinal PC proliferated and migrated at a faster rate compared to Cyp1b1+/+ retinal PC. Changes in proliferation were attributed to the decreased basal levels of apoptosis in Cyp1b1-/- retinal PC. In addition, Cyp1b1-/- PC were more resistant to apoptosis when challenged with staurosporine. Cyp1b1-/- PC were also more adherent on fibronectin and vitronectin compared to Cyp1b1+/+ PC. Cyp1b1-deficiency was also associated with altered production of various ECM proteins including thrombospondin-2 and osteopontin.
Conclusions: :
The expression of Cyp1b1 is essential for maintaining PC’s normal proliferative, migratory and adhesive properties. Thus, Cyp1b1 expression in PC may play a significant role in retinal vascular development and homeostasis.
Keywords: retinal neovascularization • oxidation/oxidative or free radical damage • extracellular matrix