No abstract

We have demonstrated that an established hamster cell line (NIL 8 M-2) will adhere to the bioceramic bioglass. The rate at which the NIL 8 M-2 cells assume a spread morphology on bioglass is density dependent and the morphology displayed by NIL 8 M-2 cells attached to bioglass is much more elongated than that displayed by NIL 8 M-2 cells attached to nonreactive glass. Precoating the bioglass with the plasma form of human fibronectin significantly reduces the density dependent nature of cell spreading. Coating the bioglass with fibronectin also reduces the time required for cell spreading and changes the morphology of the attached cells from an elongated to an extremely flattened shape. Our work raises the possibility that bone-implant adhesion might be improved by introducing molecules relevant to cell-substrate attachment into the biomaterial prior to implantation.

We have investigated the relationship of concanavalin A binding to the cell surface of normal and transformed cells and the subsequent agglutination of the transformed cells . At room temperature almost no differences could be detected in agglutinin binding between transformed and untransformed cells . At 0°C, however, where endocytosis was negligible, the transformed cells bound three times more agglutinin . However, transformed cells and trypsin-treated normal cells do not agglutinate at 0°C although the amounts of agglutinin bound at 0°C are sufficient to permit agglutination when such cells are shifted up to room temperature . Both transformed and trypsin-treated normal cells show a marked increase in agglutination at 15°C as compared to agglutination at 0°C . From this, as well as the observation that mild glutaraldehyde fixation of the cell surface inhibited agglutination but not agglutinin binding, it was concluded that concanavalin A-mediated cell agglutination requires free movement of the agglutinin receptor sites within the plane of the cell surface .A number of investigators have employed plant mal and transformed cells . We have recently agglutinins (lectins) in the study of the cell surface demonstrated that under carefully controlled condiof normal and transformed tissue culture cells tions, in which nonspecific agglutinin binding and (1-3) . It has been demonstrated that many transendocytosis of the radiolabeled agglutinin is reformed cells and protease-treated normal cells duced, transformed cells bind 3 .5 times more agglutinate at much lower concentrations of ag-[aH]concanavalin A than do the normal parent glutinin than do the normal parent cells (3, 4) . On cells (9) . We have also shown that concanavalin A the basis of these results, we had proposed a model binding alone is not sufficient to permit agglutinaof the cell surface in which the agglutinin receptor tion but that some secondary process has to occur sites of the normal cell were in a conformation on the cell surface which permits agglutination which prevented binding of the agglutinin mole-(9) . cules to the cell surface, whereas the agglutinin reRecently Sachs and his collaborators have ceptor sites of the transformed cell and the pro-demonstrated that transformed cells and trypsintease-treated normal cell were in a conformation to treated normal cells do not agglutinate at 4°C, permit agglutinin binding and thereby initiate suggesting that there is a temperature-sensitive agglutination (4) .step involved in concanavalin A-mediated aggluThis hypothesis has been investigated using tination (10, 11) . Sachs has suggested that this radiolabeled agglutinin binding assays (5-8) . Most step may be a metabolic step, possibly related to a of these investigations have demonstrated little or surface-localized enzymatic activity (10) . no difference in agglutinin binding between norNicolson and Singer have performed an elec-1 34

No abstract

No abstract