Poly(lactide-co-glycolide) (PLGA) has been believed to be a good biocompatible material for tissue engineering due to its biodegradability and non-toxicity of the monomer. However, the inflammatory reaction of adherent cells on the surface has not been discussed sufficiently. We hypothesized that the inflammatory reaction of adherent cells on PLGA might occur and could be reduced by blending a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer (PMEH) with the PLGA. PLGA/PMEH blend membranes were prepared by a solvent evaporation technique. The thermal properties of the PLGA/PMEH membrane were determined using a differential scanning calorimeter. The glass transition temperature of the PLGA/PMEH membranes was slightly decreased compared to that of a PLGA membrane. X-ray photoelectron spectrum analysis revealed that the MPC unit was exposed on the PLGA/PMEH membrane and that the surface concentration of the MPC unit on the membrane was increased with an increase in the concentration of the PMEH in the blended membrane. NIH-3T3 mouse fibroblast cells were cultured on the PLGA/PMEH membrane for 2 days. The number of adherent cells on the PLGA/PMEH membrane was decreased with an increase in the concentration of the PMEH. Using the RT-PCR method, the amount of an inflammatory cytokine, IL-1beta, mRNA expressed from adherent human premyelocytic leukemia cells on PLGA and PLGA/PMEH membranes were determined. On a PLGA/PMEH membrane containing 0.2 wt% of PMEH, the expression of IL-1beta mRNA was significantly lower than that on PLGA, but no difference in the number of adherent cells was found. Therefore, the MPC polymer was a useful additive for reducing the inflammatory reaction of adherent cells on PLGA. (C) 2002 Elsevier Science Ltd. All rights reserved.