Regulation of Viability in Corneal Endothelial Cells

The major cause of corneal opacity and resultant visual loss is a critical decrease in corneal endothelial cell density. Due to the fact that corneal endothelial cells do not generally proliferate, cell densities gradually decrease in the corneal endothelium with age. Before we can begin to aid patients with decreasing endothelial cell densities, by inhibiting cell death or stimulating cell proliferation, it is necessary to understand the basic cell signalling that underlies these processes. As human tissue is difficult to obtain, a representative animal model of corneal endothelium was devised. Analysis of cell morphology and expression of a1 type VIII collagen were used to verify that primary cells derived from an explant model of mouse corneal cells were endothelial. A range of phenotypic and functional cellular features were also analysed to assess the usefulness of primary mouse corneal endothelial cultures as a model for human corneal endothelium. These included tight junction protein localization, proliferative responses to growth factor stimulation and ERK1/2 activation following growth factor stimulation. From these analyses, it was shown that primary mouse corneal endothelial cultures provide a representative model of the human corneal endothelium. A similar comparison was also made between primary mouse corneal endothelial cultures and an SV40 transformed mouse corneal endothelial cell line. Studies revealed significant differences in propensity to proliferate, junctional integrity, ERK1/2 activation, expression of apoptotic proteins and sensitivity to staurosporine-induced apoptosis between primary cells and the SV40 transformed cell line, suggesting that the SV40 transformed cell line is a less appropriate model for primary mouse corneal endothelial cells. In conclusion, the derivation and characterisation of mouse primary corneal endothelial cells provides a better model of the corneal endothelium, that offers greater understanding of cellular responses and which may eventually lead to the development of alternative therapies for primary corneal endotheliopathies.