Proteoglycans on normal and migrating human corneal endothelium

Proteoglycans are of fundamental importance to the normal functioning of th e cornea. They consist of a core protein to which one or more glycosaminogl ycan chains are attached. Cell surface proteoglycans are known to mediate m any aspects of cell behaviour including cell adhesion, control of extracell ular matrix deposition, cell proliferation, cell migration, leukocyte adhes ion and modulation of growth factor activity. This paper describes the firs t investigation into the distribution and function of the three main classe s of proteoglycans on human corneal endothelium. Immune-gold labelling tech niques were used at the light, scanning and transmission electron microscop e level to localise heparan sulphate, chondroitin sulphate and keratan sulp hate proteoglycans on human corneal endothelium. Human corneas were freeze- wounded and kept in organ culture for 3 days in order to study the distribu tion of proteoglycans on migrating corneal endothelium. An Optimas image an alysis system was used to quantify the change in proteoglycan labelling dur ing cell migration. Labelling for chondroitin sulphate and heparan sulphate was at very low levels on normal corneal endothelium while keratan sulphat e labelling was at high levels. The wound healing experiments showed that m igrating cells had increased labelling for heparan sulphate and chondroitin sulphate with greatly decreased labelling for keratan sulphate. Statistica l analysis showed these changes were highly significant (P < 0.001). Transm ission electron microscopy revealed that chondroitin sulphate and keratan s ulphate were present throughout Descemet's membrane while heparan sulphate was concentrated at the interface of Descemet's membrane and the migrating corneal endothelial cells. The pattern of occurrence of chondroitin sulphat e, heparan sulphate and keratan sulphate on the human endothelium in normal and wounded cornea suggests that these proteoglycans are linked to the pro cess of cell migration. (C) 1999 Academic Press.