We designed a membrane culture unit on which 2 different cell lines were co-cultured to achieve selective and active transport of toxins. Hepatic origin HepG2 and renal origin multidrug-resistant gene-transduced proximal convoluted tubular cell line (PCTL-MDR) were cultured on the opposite sides of an expanded polytetrafluoroethylene membrane. The activity of testosterone hydroxylation by original HepG2 was very low; however, the cytochrome p450 (CYP) 3A4-transduced recombinant HepG2 metabolized the substrate efficiently. Testosterone added into the outer medium was hydrolyzed by HepG2, and the metabolites were preferentially transported to the inner medium by PCTL-MDR. [3H]-digoxin and [14C]-inulin were added to the outer medium; the digoxin was transported from the outer to inner space through the cell monolayer but the inulin was not, suggesting that the membrane actively transported only the substrate of the channel protein, MDR. The cells were irradiated (10 Gy) to prevent a membrane leak due to overgrowth. The irradiation did not induce apoptosis but resulted in long-lasting membrane function without leakage. The membrane co-cultured with hepatic and renal origin cells will enable a novel hemofiltration system with selective and active transport activities.