Cultured human proximal tubule cells as a model for aminoglycoside nephrotoxicity

Despite numerous clinical and animal studies, the initial injury and pathogenesis of aminoglycoside nephrotoxicity remains unclear. To compliment and extend existing research avenues, a cell culture model system representative of the human proximal tubule (HPT) was tested to determine its applicability for use in studies assessing aminoglycoside-induced cellular toxicity. For this determination, the proximal tubule cell cultures were exposed to increasing concentrations of streptomycin and monitored for cell death and light and electron microscopic changes under both confluent (resting) and subconfluent (actively-dividing) culture conditions. Confluent cultures exposed to streptomycin were also assessed for possible alterations in transport activities by monitoring the electrical properties of the cells through Ussing chamber analysis. Both the confluent and subconfluent cultures demonstrated concentration-dependent toxicity to streptomycin. Ultrastructural analysis disclosed that both actively-dividing and stationary cultures contained "myeloid bodies" within the cytoplasm, consistent with those known to occur in vivo. In studies relating cell numbers to the dosage and time of exposure to streptomycin, the confluent cultures demonstrated and "insult-recovery" period at toxic, but sub-lethal, concentration, again correlating to the known in vivo experience with this class of antibiotics. The subconfluent cultures demonstrated increased resistance to the toxic effects of streptomycin, again mimicking the clinical experience with aminoglycoside toxicity. Chamber analysis, at a streptomycin dose well below the toxic level, indicated changes in the transport activities of these cultured cells. It is proposed that the use of cultured proximal tubule cells could be a useful model system to extend current research avenues assessing the mechanism of aminoglycoside nephrotoxicity.