Liver bioengineering: from the stage of liver decellularized matrix to the multiple cellular actors and bioreactor special effects

Abstract

Liver bioengineering has been a field of intense research and popular excitement in the past decades. It experiences great interest since the introduction of whole liver acellular scaffolds generated by perfusion decellularization (1-3). Nevertheless, the different strategies developed so far have failed to generate hepatic tissue in vitro bioequivalent to native liver tissue. Even notable novel strategies that rely on iPSC-derived liver progenitor cells potential to self-organize in association with endothelial cells in hepatic organoids are lacking critical components of the native tissue (e.g., bile ducts, functional vascular network, hepatic microarchitecture, etc) (4). Hence, it is vital to understand the strengths and short comes of our current strategies in this quest to re-create liver organogenesis in vitro. To shed some light into these issues, this review describes the different actors that play crucial roles in liver organogenesis and highlights the steps still missing to successfully generate whole livers and hepatic organoids in vitro for multiple applications.

Keywords: bile duct morphogenesis; hepatoblasts; liver bioengineering; liver decellularization; liver organogenesis; liver stem cell differentiation; organ bioengineering.

Figure 1. ECM protein localization on native human liver scaffold and native human liver. Immunostaining for collagen I, III, IV, fibronectin, and laminin (as indicated) show similar ECM component distribution in prepared acellular liver bioscaffold and native human liver sections. Scale 50μm (From Hepatology with permission from Wiley and Sons).

Figure 2. Pig liver scaffold preparation. Porcine livers can also be harvested and efficiently decellularized with an identical technique as in human cadaveric donor retrieval, using cold perfusion with preserving solution via portal vein and hepatic artery. After back-table preparation, these organs were connected to a pressure controlled perfusion system, continuously infusing a decellularization solution for 24 h based on SDS. This particular system included a remote controlled pump with a pressure sensor all connected to a computer hosting the controlling software (Velasco et al. unpublished data).