co-cultures of mesenchymal cells with epithelial organoids promote fusion into bioengineered liver tissues by ECM remodeling

Human liver tissue engineering holds promise for transplantation but faces challenges replicating liver complexity. In the present study, we created bioengineered liver tissues (BLTs) utilizing three different cell types; human intrahepatic cholangiocyte organoids (ICOs), hepatic stellate cells (HSCs), and mesenchymal stromal cells (MSCs). Co-culturing with HSCs and MSCs accelerated growthand spontaneous fusion resulted in complex liver-like tissue structures. In a dynamic suspension culture, BLTs had a more compact morphology and higher expression of hepatic markers, including ALB, CYP3A4, and MRP2. We further showed that animal-derived Matrigel can be replaced by a synthetic polyisocyanide (PIC)-based hydrogel for BLTs. Importantly, PIC-based hydrogel further promoted the maturation of BLTs assessed by parameters as intracellular protein levels, morphological analysis, and metabolic activity. Transcriptomic analyses revealed mechanisms underlying tissue formation and function. To conclude, our strategy yields functional liver tissues suitable for disease modelling, drug screening, and toxicity tests, and form an important basis for future development of larger liver tissues for in vivo transplantation.