ISOLATION, CULTURE, AND CHARACTERIZATION OF ENDOTHELIAL-CELLS FROM SCHLEMMS CANAL

PURPOSE. An important god in glaucoma research has been to understand the functional contribution of trabecular meshwork (TM) and Schlemm's canal (SC) endothelia to aqueous humor outflow resistance. To date, TM cells are routinely cultured and used as a model by several laborator ies. However, there has been only limited success in isolating SC cell s. The current objective was to develop a technique for selective isol ation and culture of endothelial cells from human SC. METHODs. The ant erior chamber of human cadaveric eyes was cut into eight equal and rad ially symmetric wedge-shaped pieces. Using a dissecting microscope, a gelatin-coated suture (GO sterile nylon monofilament) was gently inser ted into the lumen of SC and advanced into the canal. The cannulated p ieces of tissue were placed in culture medium and maintained for 3 wee ks. Sutures were removed from SC and cells seeded onto 3-cm culture pl ates. Morphology, growth characteristics, and expression of endothelia l surface antigens and other cellular markers were evaluated. RESULTS. Of the 20 pairs of eyes that were cannulated, primary cells were obta ined from 13. All SC cell isolates had a fusiform morphology; formed n onoverlapping, linearly arranged monolayers; and mere contact inhibite d. Schlemm's canal cell isolates reacted with antibodies specific for CD44 (hyaluron receptor), CD54 (intercellular adhesion molecule-1, ICA M-1), tissue-type plasminogen activator, and TM-inducible glucscortico id-responsive protein-myocilin (TIGR-MYOC). Unlike TM cells, however, TIGR-MYOC protein was not induced in SC cells after long-term dexameth asone treatment. Schlemm's canal cells endocytosed low density lipopro tein and acetylated low-density lipoprotein, and in the presence of Ma trigel organized into multicellular tubelike structures. CONCLUSIONS. Cannulation of SC with gelatin-costed suture material is an effective method for the isolation of human SC cells and provides a cellular mod el to study the potential role of SC cells in aqueous humor outflow fu nction.