The efficient design of a membrane bioreactor for cells culture needs the complete characterization - both experimentally and theoretically -of the transport phenomena for metabolites, catabolites, cell regulatory and immune-related soluble factors. In this work, experiments and theoretical calculations have been carried out in order to discern the simultaneous influence of both diffusive and convective mechanisms to the transport of metabolites. In particular, the transmembrane mass flux of glucose, bovine serum albumin (BSA), apotransferrin and immunoglobulin G was experimentally measured, under pressure and concentration gradients, through high-flux microporous hydrophilic poly-ether-sulphone (PES-HFMs) and poly-sulphone hollow fiber membranes (PS-HFMs).