Characterization of the proteome and metabolome of human liver sinusoidal endothelial-like cells derived from induced pluripotent stem cells.

The liver is a complex organ composed of several cell types organized hierarchically. Among these, liver sinusoidal endothelial cells (LSECs) are specialized vascular cells known to interact with hepatocytes and hepatic stellate cells (HSCs), and to be involved in the regulation of important hepatic processes in healthy and pathological situations. Protocols for the differentiation of LSECs from human induced pluripotent stem cells, hiPSCs, have been proposed and in-depth analysis by transcriptomic profiling of those cells has been performed. In the present work, an extended analysis of those cells in terms of proteome and metabolome has been implemented. The proteomic analysis confirmed the expression of important endothelial markers and pathways. Among them, the expression of patterns typical of LSECs such as PECAM1, VWF, LYVE1, STAB1 (endothelial markers), CDH13, CDH5, CLDN5, ICAM1, MCAM-CD146, ICAM2, ESAM (endothelial cytoskeleton), NOSTRIN, NOS3 (Nitric Oxide endothelial ROS), ESM1, ENG, MMRN2, THBS1, ANGPT2 (angiogenesis), CD93, MRC1 (mannose receptor), CLEC14A (C-type lectin), CD40 (antigen), and ERG (transcription factor) was highlighted. Besides, the pathway analysis revealed the enrichment of the endocytosis, Toll-like receptor, Nod-like receptor, Wnt, Apelin, VEGF, cGMP-PCK, and PPAR related signaling pathways. Other important pathways such as vasopressin regulated water reabsorption, fluid shear stress, relaxin signaling, and renin secretion were also highlighted. At confluence, the metabolome profile appeared consistent with quiescent endothelial cell patterns. The integration of both proteome and metabolome datasets revealed a switch from fatty acid synthesis in undifferentiated hiPSCs to a fatty oxidation in LSECs and activation of the pentose phosphate pathway and polyamine metabolism in hiPSCs-derived LSECs. In conclusion, the comparison between the signature of LSECs differentiated following the protocol described in this work, and data found in the literature confirmed the particular relevance of these cells for future in vitro applications.