Bioreactor type and operating conditions influence cell response to polymeric material properties

Petri dish culture is routinely used to test the effect of biomaterial properties on mammalian cells although significant transport resistance hinders the transport of gaseous metabolites to the cells and culture conditions change in time. In this paper we report on the culture in a continuous-flow recycle bioreactor of rat liver cells adherent on hydrophilized polypropylene membranes at increasing ammonia concentrations. Membranes exhibited varying bulk and surface wettability. Rates of all investigated metabolic reactions increased with increasing ammonia concentrations and with increasing surface wettability, at any ammonia concentration. Metabolic differences among cells cultured on membranes with different wettability became more and more evident at increasing ammonia concentrations. Rate dependence on membrane surface wettability changed with the investigated metabolic pathway, being the strongest for urea synthesis. We conclude that culture in continuous-flow bioreactors may enhance cell metabolic activity, their sensitivity towards the material properties and the sensitivity of the biocompatibility test.