COLLAGEN AND FIBRONECTIN IMMOBILIZATION ON PHEMA MICROCARRIERS FOR HEPATOCYTE ATTACHMENT

Polyhydroxyethylmethacrylate (PHEMA) microcarriers in a size range of 150-250 mu m were prepared by a suspension polymerization in an aqueou s phase containing magnesium oxide. The hydroxyl groups on the PHEMA m icrocarriers were activated by cyanogen bromide. In order to improve c ell attachment, cell-adhesive proteins, namely, collagen and fibronect in were immobilized onto PHEMA microcarriers. The nonspecific adsorpti on values for collagen and fibronectin were 0.10 mg collagen/g PHEMA a nd 0.044 mg fibronectin/g PHEMA, respectively. Collagen and fibronecti n immobilization on PHEMA microcarriers were studied at different pH b y using single protein solutions containing different amounts of prote ins, at a constant temperature of 20 degrees G. The maximum immobiliza tions were 0.85 mg collagen/g PHEMA (at pH: 9.5) and 0.52 mg fibronect in/g PHEMA (at pH: 7.4). Hepatocyte attachment onto these biologically modified PHEMA microcarriers was studied. Hydrophilic PHEMA microcarr iers did not support cell attachment. High hepatocyte attachment yield s (up to 75% surface coverage) were observed on collagen and fibronect in immobilized PHEMA microcarriers.