Fibrinogen improves liver function via promoting cell aggregation and fibronectin assembly in hepatic spheroids

Many key functions performed by the liver depend on the interaction between parenchymal cells and the microenvironment comprised of neighboring cells and extracellular matrix. The biological macromolecules in the matrix, which are dynamically changing, participate in various physiological processes through interactions with cell surface receptors, antigens, and ion channels. We found the rat liver biomatrix scaffold (LBS) prepared from adult rats is more effective in enhancing the function of hepatic spheroids than those derived from newborn or senile rats. Combined with matrisome and bioinformatics analyses, we further found that the glycoproteins, fibronectin and fibrinogen may have special potential for improving hepatocyte function. Human primary hepatocyte organoids and HepaRG spheroids showed more mature hepatocyte phenotype after adding fibronectin and fibrinogen to the culture system. During the cultivation of hepatic spheroids, fibrinogen resulted in an increase in cell-cell junction by promoting cell aggregation and helping fibronectin to assemble on cell surface, which resulted in activation of Wnt/β-catenin pathway. Fibronectin-integrin αVβ1-Wnt/β-catenin may be the axis of signal transduction in parenchymal cell microenvironment. Importantly, fibrinogen enhances the signal transduction. These results suggest that the addition of fibronectin and fibrinogen to the 3D culture system is a new strategy for inducing parenchymal cell functional maturation.