Imaging the cellular crosstalk of sinusoidal endothelium

Despite recent landmarks discoveries on angiocrine gatekeeper functions of liver sinusoidal endothelial cells (LSEC) during liver development, regeneration and immunosurveillance, our understanding of the cellular crosstalk of... [ view full abstract ]

Despite recent landmarks discoveries on angiocrine gatekeeper functions of liver sinusoidal endothelial cells (LSEC) during liver development, regeneration and immunosurveillance, our understanding of the cellular crosstalk of LSEC with the cells of their surrounding microenvironment is still limited. This is largely due to the lack of high-resolution techniques suitable to physically image the cellular interactions in complex vascular networks in vivo and in situ in 2D and in 3D. Here we used advanced microscopy methodology to establish an imaging platform designed to study the interaction of LSEC with surrounding parenchymal cells, circulating cells as well as tumor cells. First, we developed a 3D reconstruction system of the sinusoidal vasculature to yield an accurate quantification of intravascular, extravascular and transmigrating cells in relation to their position. Moreover, by establishing a correlative confocal-electron microscopy technique, we obtained a detailed (1-2 nm resolution) visualization of the cellular machinery employed by different interacting cells. Next, to correlate morphological and functional parameters, we provide additional imaging readouts, suitable for an in situ analysis of liver zonation, hypoxia of hepatocytes and angiocrine factor production. Lastly, employing intravital microscopy techniques, we quantified different hemodynamic parameters (blood flow velocity and shear stress) at single sinusoidal cell resolution. Taken together, the established portfolio of advanced imaging techniques provides a powerful toolbox to unravel at highest cellular and subcellular resolution the crosstalk of LSEC with other cells during development, homeostasis, repair and tumorigenesis, including the mechanisms of microvascular invasion and intra-hepatic metastasis. 

Key-words: LSEC, advanced imaging, liver zonation, regeneration, HCC.