Fig. 3. A bioartificial kidney.

Schematic representation of a bioartificial kidney integrated with a conventional dialysis filter in a series configuration. First, the patient’s blood flows through a dialysis filter, which removes small molecules and medium-sized molecules (up to 45 kDa) and excess fluid. The blood then enters the bioartificial kidney, which consists of immortalized proximal tubule cells cultured on polymeric hollow fibre membranes. These cells take up protein-bound uraemic toxins from the blood after release of the molecules from the plasma protein (predominantly albumin) to the free solute, owing to the higher affinity of the solutes for the basolateral influx transporters, which can then be secreted into the dialysate via the actions of apical efflux transporters. The blood is then returned to the patient.