An ECVAM task force on nephrotoxicity has been established to advise, in particular, on the follow-up to recommendations made in the ECVAM workshop report on nephrotoxicity testing in vitro. Since this workshop was held, in 1994, there have been several improvements in the techniques used. For example, the duration of renal slice viability, and the maintenance of functional activities in slices, have been improved by using dynamic incubation systems with higher oxygen tensions and more-appropriate cell culture media. Highly differentiated primary cultures of pig, human and rabbit proximal tubule cells have been established by using specific cell isolation procedures and/or selective culture media. To date, the most comparable phenotypic expression and transepithelial transport capacities to proximal tubules in vivo have been obtained with primary cultures of rabbit proximal tubule cells which are grown on bicompartmental supports; in this system, transepithelial substrate gradients are generated and the transepithelial transport of both organic anions and cations is highly active. This in vitro system has been selected by ECVAM for further evaluation and prevalidation. Industrial needs in the area of nephrotoxicity testing have been identified, and recommendations are made at the end of this report concerning possible future initiatives.
Hormonal Actions and Interactions in Proximal Tubule Cells Associated with the Development of Chronic Kidney Disease
