Research Assistant Professor The University of Hong Kong, Hong Kong
Abstract: Acute liver failure is associated with a 93% one-month mortality rate after onset, along with a 12.2% mortality rate for patients awaiting liver transplantation. While bioartificial liver offers a potential alternative for improving liver function, it faces significant challenges, including limited cell sources, lack of internal vascularization, and the inability to restore immune homeostasis. Therefore, tissue engineering that aim to restore the liver microenvironment by integrating bioprinting and stem cell technologies hold great promise. In this study, direct ink writing-based multi-nozzle bioprinting was employed to construct an interlaced prototype using degradable microfibrous bioink and sacrificial bioink. Mesenchymal stem cells (MSCs), umbilical vein endothelial cells (HUVECs), and expanded potential stem cell (EPSC)-derived immune cells were embedded into the bioinks. The printed construct was evaluated through imaging. The bioengineered tissue was then transplanted into the liver subcapsular space to assess in vivo tissue compatibility and treatment efficacy. The results demonstrated that the tissue composition, comprising alginate, gelatin, and gelatin methacrylate, ensured the anisotropy, printability, and biocompatibility of the hydrogels. HUVEC-MSC co-culture in microfibrous hydrogels exhibited a more elongated and stretched morphology compared to HUVEC monoculture by day 14. HUVECs lined the heterogeneous interconnected lumens, facilitating macroscale vessel formation after a one-day incubation and the removal of HUVEC-laden sacrificial bioink. Subsequently, HUVECs autonomously formed capillary networks (microscale vessels) within the microfibrous bioinks. After seven days of co-culture, these cells sprouted and invaded the surrounding microfibrous hydrogels, promoting angiogenesis. In the mouse model, blood cells and CD31+ endothelial cells were observed infiltrating the bioengineered tissue. This study represents a novel application of 3D bioprinting and stem cell technologies to create a transplantable structure with well-formed capillary networks, offering a potential solution to the shortage of liver donors. This innovation also holds promise for developing vascularized artificial livers for liver failure treatment.
Funding Source: Theme-based Research Scheme (T12-703/19-R) General Research Fund (17113924, 17109422)
