Abstract
Abstract: :
Purpose. Thrombospondins are a family of at least five extracellular matrix proteins with complex roles in cell:cell and cell:matrix interactions. Human keratocytes synthesise the first three members of this family following corneal stromal injury. They also make thrombospondin 1 (TSP-1) when in a collagen matrix in vitro, although to date we have been unable to demonstrate a specific role for TSP-1 in these preparations. In the present study, we investigated whether human keratocytes produce thrombospondins 2 and 3 (TSP-2, TSP-3) when the cells are cultured in collagen. In addition, we examined the effect of antibodies to TSP-2 and TSP-3 on the behaviour of cells in keratocyte-populated collagen matrices. Methods. Human keratocyte-populated collagen matrices were evaluated for TSP-2 and TSP-3 mRNA. Sections of matrices were stained by immunohistochemistry for TSP-2 and TSP-3. Keratocyte-populated collagen matrices were treated with antibodies specific to TSP-2 or TSP-3 and these preparations were evaluated for contraction and keratocyte morphology. Results. Keratocytes in collagen matrices contained mRNA for TSP-2 and TSP-3, and the cells were immunoreactive for both proteins. Compared to controls, an antibody specific to the N-terminal domain of TSP-2 significantly inhibited matrix contraction for up to 10 days at a concentration of 20 µg /ml antibody. At 2 µg/ml TSP-2 antibody concentration significant inhibition occurred up to 3 days. Keratocytes in TSP-2 antibody treated collagen matrices adopted a rounded shape, whereas keratocytes in control matrices exhibited a fibroblastic appearance. Antibody specific to TSP-3 had no effect on matrix contraction or keratocyte morphology. Conclusions. Keratocytes synthesise TSP-2 and TSP-3 when seeded in collagen matrices. Antibody specific to TSP-2 reversibly inhibits keratocyte-mediated collagen matrix contraction. TSP-2 appears to play a key role in human keratocyte: collagen matrix interactions and therefore may have an important function during corneal stromal repair.
Keywords: cornea: stroma and keratocytes • extracellular matrix • protein structure/function