METABOLIC EXPERIMENTAL PATHOLOGY UNIT

Our group (Experimental Metabolic Pathology Unit) studies the role of cyclooxygenase 2 (COX-2) in liver pathophysiology. Cyclooxygenase (COX) is the enzyme that catalyzes the limiting step in the synthesis of prostanoids. Prostaglandins play an important role in numerous biological processes such as platelet aggregation, gastric mucosal maintenance, reproduction, etc. and in pathological processes such as inflammation and cancer. In the liver, COX-2 expression occurs during pathophysiological circumstances involving regeneration, acute damage, differentiation processes and cell proliferation, and in situations such as viral infection, cirrhosis and hepatocellular carcinoma. Our group, thanks to the generation of cellular models and a transgenic model of constitutive overexpression of human COX-2 in hepatocytes, has been able to show that COX-2 expression in hepatocytes protects against liver damage induced by hyperglycemia, insulin resistance and obesity, as well as in steatohepatitis, fibrosis, and ischemia/reperfusion damage. We are currently assessing the therapeutic potential of COX-2 in the treatment of non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) thanks to a new conditional transgenic model generated in the group using CRISPR/Cas9 technology (B6JRccHsd-Tg(ROSA)26Sor^{tm1(CAG-PTGS2-PP2A-GFP)}/Upme), and the design, development and validation of nanoparticles to specifically target hepatocytes for COX-2 expression. An important point arising from these studies is the feasibility of translating any positive result to humans. This is particularly relevant in the current investigation since a major challenge of our proposal is to have proof of concept of the efficacy of these innovative treatments in human tissue before performing any type of clinical test. 2D monocultures often lack cell-cell and cell-matrix interactions and thus fail to mimic cellular functions and signaling pathways present in tissues. Tissue explants or slices may transiently capture physiologically relevant cell organization and interactions, but they tend to lose their phenotype and are difficult to maintain for extended periods. Thus, we are developing an in vitro human system to test the nanoparticles, modeling NAFLD/NASH. First, we will use stellate cells obtained from pluripotent stem cells maintained as 3D spheroids with human hepatocytes, exposing them to a fibrogenic response and evaluating the role of nanoparticles in reversing the fibrotic process. Cell spheroids lack cells with the capacity for self-renewal and differentiation. However, organoids recapitulate a large number of biological parameters including the spatial organization of heterogeneous tissue-specific cells, cell-cell interactions, cell-matrix interactions, and certain physiological functions generated by tissue-specific cells within the organoid. Therefore, our main objective is the development of liver organoids as an in vitro system to study the therapeutic potential of COX-2.