Renal failure continues to cause a major burden of morbidity and mortality in both its acute and chronic forms, regardless of advances in current renal replacement therapies. A bioartificial kidney that includes a conventional dialysis filter and a renal tubule assist device containing approximately 10(8) renal proximal tubule cells was recently successfully engineered. This therapeutic modality may decrease the survival gap between current renal replacement therapies and healthy kidney functions and may lessen the heavy burden of morbidity and mortality associated with renal failure, both acute and chronic, in the near future.