A transgenic rat hepatocyte - Kupffer cell co-culture model for evaluation of direct and macrophage-related effect of poly(amidoamine) dendrimers

- Cells were prepared from rats stably expressing GCaMP2 Ca2 + sensor protein.
- G5 induced Ca2 + oscillation and sustained Ca2 + signals at 1 and10 μM in hepatocytes.
- Activation of Kupffer cells by LPS and G5 decreased the inducibility of CYP2B1/2.
- G5 reduced the canalicular efflux of bilirubin in co-cultures.
- G5 stimulated the uptake and canalicular efflux of taurocholate.

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 1 μM 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.

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