Integrated mesenchymal and extracellular cues drive bioengineered liver tissue formation and function

Human tissue engineering holds great promise for creating physiological models while facing challenges replicating natural complexity, including cellular and extracellular cues. Current approaches often miss the incorporation of major bioengineering factors (i.e., cellular complexity, well-defined extracellular matrix (ECM) mimicry, dynamic stimuli). We bioengineered liver tissues (BLTs) utilizing human intrahepatic cholangiocyte organoids (ICOs), hepatic stellate cells (HSCs), and mesenchymal stromal cells (MSCs), a synthetic polyisocynide (PIC)- based hydrogel, and dynamic suspension culture (DS) to represent major bioengineering factors. Both mesenchymal cells (HSCs and MSCs) accelerated organoid growth and promoted spontaneous complex liver-like microtissue (BLT) formation. DS and PIC further improved either BLT formation or functionality. Transcriptomic analyses revealed the integrated cellular and extracellular cues in BLT formation and maintenance. To conclude, organoids augmented with mesenchymal cells in chemically defined hydrogels yield functional BLTs 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. The bioengineering strategy developed in this study can be extended to engineer other types of tissues and also be utilized to investigate the interaction of different bioengineering factors.