A hepatoprotective role of peritumoral non-parenchymal cells in early liver tumorigenesis.

Various 3-dimensional (3D) models of hepatocytes (HCs) have been established to assess liver functions in vitro. Contribution of the hepatic non-parenchymal cells (NPCs), however, is largely neglected in these models. Here, we report a comparative study of hepatic spheroids generated from freshly isolated mouse whole liver cells (WLCs) and HCs (referred to as SphWLC and SphHC, respectively). We found that HC differentiation was preserved better in SphWLC than in SphHC, and when cocultured with liver tumor spheroids (SphT), SphWLC showed a more potent suppression on SphT growth compared to SphHC. Histological characterization revealed a marked activation and accumulation of hepatic stellate cells (HSCs) at the SphWLC:SphT interface. We found that mixing HSCs in both 3D and 2D HC:T cocultures provided a potent protection to HCs over tumor-induced cell death. Activation of HSCs at the tumor border was similarly found in liver tumors from both mice and patients. Overall, our study suggests a hepatoprotective role of peritumoral HSCs in liver tumorigenesis, and the potential application of SphWLC as a useful 3D model for dissecting liver's response to tumorigenesis in vitro.