In vitro cytotoxicity assay with selected chemicals using human cells to predict target-organ toxicity of liver and kidney.

In order to elucidate the feasibility of predicting liver and kidney target-organ toxicity using in vitro cytotoxicity assay, cytotoxicity of selected chemicals, acetaminophen (AAP), mitomycin (MMC), cupric chloride (CuCl2), phenacetin, cadmium chloride (CdCl2) and aristolochic acid (AA), was studied using human hepatoma (Bel-7402) cells and human renal tubular epithelial (HK-2) cells. Cell viability and mitochondrial permeability transition (MPT) were assessed by the neutral red (NR) assay and laser scanning confocal microscope, respectively. The results of the NR assay indicated that cytotoxicity of hepatoxicants, AAP, MMC and CuCl2 in liver cells was higher than that in kidney cells. Cytotoxicitiy of nephrotoxicant, CdCl2 was lower in liver cells than that in kidney cells, but nephrotoxicant phenacetin and AA was higher cytotoxicity in liver cells than that in kidney cells. The cytotoxicity of AAP and phenacetin was strengthened in the presence of S9 mixture, indicating that they are metabolism-mediated cytotoxicants. All selected chemicals disrupted MPT in dose-dependent manner. Linear regression analysis revealed a good correlation between the IC50 values of cytotoxicity and the EC50 values of MPT in Bel-7402 cells and HK-2 cells (R2 = 0.987 and 0.823, respectively). Cytotoxicity assay in vitro using specific cells show good compatibility with target-organ toxicity in vivo. However, limitations of in vitro cytotoxicity assay are due to its incomplete process of ADME and the defect of predicting chronic toxicity effect after long-term exposure to a chemical.