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

Various 3D models of hepatocytes (HCs) have been established to assess liver functions in vitro. The 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 Sph(WLC) and Sph(HC), respectively). We found that HC differentiation was preserved better in Sph(WLC) than in Sph(HC), and, when co-cultured with liver tumor spheroids (Sph(T)), Sph(WLC) showed more potent suppression of Sph(T) growth compared to Sph(HC). Histological characterization revealed marked activation and accumulation of hepatic stellate cells (HSCs) at the Sph(WLC):Sph(T) interface. We found that mixing HSCs in both 3D and 2D HC:tumor co-cultures provided potent protection to HCs against 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 Sph(WLC) as a useful 3D model for dissecting the liver's response to tumorigenesis in vitro.