Evaluation of Na+ active transport and morphological changes for bioartificial renal tubule cell device using...

The function of current hemodialysis as an artificial kidney is insufficient because of the lack of reabsorptive function. In this study, we intend to develop a bioartificial renal tubule cell device (RTD) using tubular epithelial cells and artificial membranes and to evaluate the reabsorptive function of the confluent layers. Madin-Darby canine kidney (MDCK) cells were cultured on a nucleopore polycarbonate membrane for up to 4 weeks after confluence to examine the influence of the culture period on their ability to transport Na+ actively using Na+/K+ATPase (NKA). The results were (1) active Na+ transport of the cells averaged 24.8 mM/m(2) x 24 h during the initial 2 weeks after confluence and then decreased to about 4.2 mM/m(2) x 24 h during the next 2 weeks; (2) NKA localized on the basal-lateral sides of the cells during the initial 2 weeks, whereas it also localized on the apical side of the cells during the next 2 weeks; (3) long-term culture resulted in an increased number of upheaving cell mass, increased fatty droplets in the cells, and necrosis; and (4) scanning electron microscopy showed fewer microvilli 3-four weeks after confluence. It is concluded that the culture period is critical for developing RTD using cultured renal tubular epithelial cells.