The influence of polymeric membrane surface free energy on cell metabolic functions

In membrane bioartificial organs using isolated cells, polymeric semipermeable membranes are used as immunoselective barriers, means for cell oxygenation and also as substrata for adhesion of anchorage-dependent cells. The selection of cytocompatible membranes that promote in vitro cell adhesion and function could be dependent on its membrane properties. In this study we investigated the physicochemical aspects of the interaction between the membrane and mammalian cells in order to provide guidelines to the selection of cytocompatible membranes. We evaluated the metabolic behavior of isolated liver cells cultured on various polymeric membranes such as the ones modified by protein adsorption. The physico-chemical properties of the membranes were characterized by contact angle measurements. The surface free energy of membranes and their different parameters acid (gamma (+)), base (gamma (-)) and Lifshitz-van der Waals (gamma (LW)) were calculated according to Good-van Oss's model. The adsorption of protein modified markedly both contact angle and membrane surface tension. In particular, membrane surface free energy decreased drastically with increased water contact angle. For each investigated membrane we observed that liver specific functions of cells improve on hydrophilic membrane surfaces. For all investigated membranes the rate of ammonia elimination increased with increasing of membrane surface free energy. (C) 2001 Kluwer Academic Publishers.