Fibrinogen-dependent adherence of macrophages to surfaces coated with poly(ethylene oxide)/poly(propylene oxide) triblock copolymers.

The role of fibrinogen in the adherence of macrophages to polymer surfaces was studied using a human cell line (THP-1 cells) and polystyrene-divinylbenzene beads coated with poly(ethylene oxide)/poly(propylene oxide) copolymers of the form PEO alpha PPO beta PEO alpha. The amphiphilic character of the surface of the beads was varied using a series of copolymers with constant PPO core lengths but different PEO segments. Fibrinogen-dependent adherence of monocytes/macrophages to the modified beads was then assessed. The adherence of THP-1 cells to copolymer-coated beads correlates well with the amount of fibrinogen bound to the beads. Those beads coated with the most hydrophobic surfactant molecules bound the most fibrinogen and the most cells. On these surfaces, the concentration of fibrinogen was less than half that of the protein on unmodified beads. Despite the lower amount of bound fibrinogen, the number of adherent cells was 37% greater than the number of adherent cells on fibrinogen-coated, copolymer-free beads. Beads coated with the most hydrophilic surfactants bound just 10% the amount of fibrinogen bound to unmodified beads. On these surfaces, the number of adherent cells was decreased by approximately 25% with respect to the number of cells bound to beads coated with fibrinogen alone. We propose that the hydrophobic surfactant molecules may act as inflammatory agents by facilitating fibrinogen-dependent cellular adhesion.