Increasing number of papers demonstrate that Kupffer cells (KCs) play a role in 
the development of drug induced liver injury (DILI). Furthermore, elevated 
intracellular Ca2+ level of hepatocytes is considered as a common marker of 
DILI. Here we applied an in vitro model based on hepatocyte mono- and 
hepatocyte/KC co-cultures (H/KC) isolated from transgenic rats stably expressing 
the GCaMP2 fluorescent Ca2+ sensor protein to investigate the effects of 
polycationic (G5), polyanionic (G4.5) and polyethylene-glycol coated neutral (G5 
Peg) dendrimers known to accumulate in the liver, primarily in KCs. Following 
dendrimer exposure, hepatocyte homeostasis was measured by MTT cytotoxicity 
assay and by Ca2+ imaging, while hepatocyte functions were studied by CYP2B1/2 
inducibility, and bilirubin and taurocholate transport. G5 was significantly 
more cytotoxic than G4.5 for hepatocytes and induced Ca2+ oscillation and 
sustained Ca2+ signals at 1μM and10 μM, respectively both in hepatocytes and 
KCs. Dendrimer-induced Ca2+ signals in hepatocytes were attenuated by 
macrophages. Activation of KCs by lipopolysaccharide and G5 decreased the 
inducibility of CYP2B1/2, which was restored by depleting the KCs with 
gadolinium-chloride and pentoxyphylline, suggesting a role of macrophages in the 
hindrance of CYP2B1/2 induction by G5 and lipopolysaccharide. In the H/KC, but 
not in the hepatocyte mono-culture, G5 reduced the canalicular efflux of 
bilirubin and stimulated the uptake and canalicular efflux of taurocholate. In 
conclusion, H/KC provides a good model for the prediction of hepatotoxic 
potential of drugs, especially of nanomaterials known to be trapped by 
macrophages, activation of which presumably contributes to DILI.