Abstract
Purpose:
Our lab and others have demonstrated that both Lamina Cribrosa (LC) and Trabecular Meshwork (TM) cells are central to the glaucoma disease process by producing Extracellular Matrix (ECM) proteins which harden the respective tissue (pro-fibrotic process). In addition, previous work from our group has shown that there are higher levels of ECM proteins in LC cells obtained from glaucoma donors compared to normal controls. The purpose of this research project was to assess the ability of normal and glaucomatous human LC and TM cells to interact with their surrounding extracellular matrix.
Methods:
Human LC and TM cells were grown on a range of cellular matrices of increasing stiffness. The response of cells to differing environments was assessed by analysis of cell movement, growth and contractility processes. An analysis of the in-vitro migratory, proliferative and contractile capacity of trabecular meshwork and lamina cribrosa cells obtained from normal and glaucoma patient donors was performed by means of scratch wound assays, indirect immunofluorescence, SDS-PAGE and quantitative PCR analysis of monolayer versus 3D culture conditions.
Results:
Preliminary data shows the ability of the stiffening-ECM to induce phenotypic changes in normal TM cells such that they adopt an abnormal (fibroblastic) morphology. We have found cellular processes of migration, proliferation and contractility to be altered in the glaucomatous disease state. Furthermore, normal and glaucomatous TM cells seeded onto a laminin-rich ECM display disparate patterns of cellular network organisation. Glaucomatous TM cells have a higher proliferative index than normal TM cells, as judged by Ki67 staining. TM cells treated with the pro-fibrotic cytokine Transforming Growth Factor beta (TGF-beta) express elevated levels of fibrotic markers (e.g. snail, thrombospondin (TSP1), vimentin; P < 0.05). We propose TGF-beta and one of its activators TSP1 as major factors which drive abnormal cell behaviour, and consequently, irreversible disease progression.
Conclusions:
We believe that a 'matrix-stiffening model' proves a reliable tool with which to detect the differential responses of normal versus glaucomatous cells to the extracellular environment. This research project has enabled the definition of normal versus disease cell behaviour on a molecular level.
Keywords: 519 extracellular matrix •
735 trabecular meshwork •
512 EMT (epithelial mesenchymal transition)