Expression of PDGF receptor-alpha in corneal myofibroblasts in situ

Abstract

The purpose of this study was to investigate the expression of platelet-derived growth factor receptor-alpha (PDGFR-alpha) in the myofibroblasts of corneas with stromal haze. Central corneal sections from rabbit eyes that had -9 diopter PRK were analyzed by immunocytochemistry (IHC) for the expression of PDGFR-alpha at 4 week after surgery. PDGFR-alpha was expressed immediately beneath the epithelial basement membrane in the anterior stroma. Double IHC studies revealed the expression of PDGFR-alpha in the anterior stroma co-localized with alpha-smooth muscle actin (SMA) marker for myofibroblasts. In vitro studies have suggested that PDGF is important in the development and viability of myofibroblasts after corneal injury. Expression of PDGFR-alpha in myofibroblasts supports these findings.

Figure

Double immunohistochemistry for PDGF receptor–α and α-smooth muscle actin in rabbit corneas that developed haze after -9D PRK. The vertical bar in each panel represents an artifactual separation beneath disordered extracellular matrix in the sub-epithelial stroma and the deeper stroma that nearly always occurs during sectioning of rabbit corneas with haze. A. Cell nuclei stained blue with DAPI. B. PDGFR–α positive cells beneath the epithelial basement membrane (arrows) stained for PDGFR-α (red). Note that keratocyte cells that are deeper in the stroma (arrowheads) appeared to have very low levels of PDGFR-α. C. SMA-positive cells beneath the epithelial basement membrane (arrows) stained for α-smooth muscle actin (green). D. Overlay of red, blue and green fluorescence shows co-localization of PDGFR–α and α-SMA in cells (arrows) in the sub-epithelial stroma. Mag. 400X.