CELLULAR AND CYTOSKELETON MORPHOLOGY AND STRENGTH OF ADHESION OF CELLS ON SELF-ASSEMBLED MONOLAYERS OF ORGANOSILANES

objective of this study was to explore the potential use of self-assem bled monolayers (SAMs) of alkylamine and arylalkyamine as well-defined , homogeneous, tailored in vitro model surfaces for exploring the effe ct of hydrodynamic flow on morphology and strength of adhesion of huma n umbilical vein endothelial cells. The cell surface area, shape, f-ac tin distribution, and adhesion strength of human umbilical vein endoth elial cells cultured on self-assembled monolayers of organosilanes wer e found to be dependent on the chemical composition of the organosilan e film and the magnitude of wall shear stress. The direct effects of t he differences in chemistry between the two silanes, in modulating cel lular response, are probably only secondary to the modulation of cellu lar functions mediated by differential protein adsorption and conforma tion on the two silanes. For short seeding times (30 min), prior to ap plication of flow, both substrate chemistry and shear stress modulated the cellular morphology and cytoskeletal organization. For longer see ding times (24 h), prior to application of flow, the chemistry of the underlying surface was the dominant variable in modulating cellular mo rphology, while the hydrodynamic shear stress modulated the cytoskelet on organization. Cells on N-(2-aminoethyl)-3-aminopropyl trimethoxysil ane (EDA) were pleomorphic, while cells on inoethyl)amino)methyl)pheny lethyl)trimethoxysilane (PEDA) expressed a rounded morphology. Applica tion of an incrementally loaded how regime (0.07-1.25 ml/s) resulted i n a time- and shear stress-dependent (10-180 dyn/cm(2)) detachment of cells, with the cells on EDA depicting higher resistance to wall shear stress. Cellular morphology correlated with the strength of adhesion; cells with rounded morphology on a hydrophobic silane, PEDA, were les s tightly bound to the silane, while spread cells on a hydrophilic sil ane, EDA, were more tightly bound. The higher surface free energy of E DA is speculated to influence the increased cell spreading and strengt h of adhesion observed in these studies. The presence of the phenyl gr oup in PEDA reduces the surface free energy and may account for the re duced spreading and lower strength of adhesion. The use of well-define d systems, such as monolayer organosilanes, with tunable surface physi cochemical properties may serve to deconstruct the complex interaction of cells with extracellular matrix components: surface charge, surfac e hydrophobicity, and other short- and long-range forces can be indivi dually controlled and correlated with cellular functions, The organosi lane monolayers could serve as the building blocks for sequential addi tion of proteins or cell adhesive/cell repulsive cues to stepwise engi neering and construction of more complex systems resembling ECM matric es, (C) 1998 Academic Press.