The Role of Extracellular Matrices in Retinal Pigment Epithelial Cell Migration

Background: To identify which extracellular matrix components modify retinal pigment epithelial cell migration and their interplay with matrix metalloproteinases in directing the behaviour of the cells in agarose droplets, an in-vitro model for cellular migration. Methods: Migration of the cells from agarose droplets on coated tissue culture plastic (fibronectin, laminin and collagen types: I and IV) in the presence as well as absence of serum was evaluated by using phase contrast microscopy and computer analysis of captured images. Expression of metalloproteinases -1, 2 and 9 by retinal pigment epithelial cells was determined by immunocytochemistry and was confirmed by western blotting. In addition, the effect of metalloproteinases inhibitor, batimastat (BB-94), on the cell migration and expression of MMPs were studied. Results: Retinal pigment epithelial cells migrated from agarose droplets in the presence of serum and fibronectin acted as an additional stimulus to migration, while laminin and collagen type IV inhibited migration in a dose dependent manner. Metalloproteinases -1, 2 and 9 were expressed by retinal pigment epithelial cells in culture as shown by immunocytochemistry and by western blotting. Expression of metalloproteinases on western blots was inhibited by use of BB-94. BB-94, also inhibited cellular migration from agarose droplets in a dose dependent manner. Conclusions: Retinal pigment epithelial cells migrate in the presence of fibronectin while expression of metalloproteinases may reflect cellular behaviour during PVR in which migration of cells from their basement membrane on to retinal surfaces requires an interaction between ECM protein and enzymes such as metalloproteinases to permit cellular invasion.