Over 4500 mm3 Engineered Liver Scaffold for Implantable Artificial Liver

Abstract

Liver diseases, encompassing conditions from hepatitis to cirrhosis, present a global health challenge affecting millions and straining healthcare systems. These diseases are often debilitating and life-threatening. Liver transplantation, long an essential life-saving procedure for patients with end- stage liver disease, is hindered by a constant shortage of suitable donor organs and the need for lifelong immunosuppression to prevent graft rejection. A promising solution arises in liver tissue engineering, which aims to create functional liver tissue using methodologies like decellularized extracellular matrix scaffolds and 3D bioprinting. Liver tissue engineering aims to diminish reliance on organ donors by using a patient's own cells to create bio-engineered liver tissue. In doing so, this field promises to substantially reduce the challenges associated with organ shortages and the need for lifelong immunosuppression, effectively minimizing complications from immune-related responses. Part 1 of this dissertation comprises two pivotal chapters. Chapter 1 provides information on the liver anatomy. We delve into the liver's components, from the diversity of cell types to the complexities of the extracellular matrix. The chapter also dissects the essential role of growth factors in orchestrating the liver's functions. The liver regeneration process, a unique attribute of the liver, is unveiled. It also addresses the sobering reality of liver diseases, explaining various afflictions, their causes, and their profound implications for liver health. Chapter 2 ventures into liver tissue engineering, introducing the utilization of various cells and biomaterials for creating artificial liver tissues. Here, we explore the techniques and methodologies that underpin this field. Liver tissue engineering presents a promising avenue, blending advanced science and technology, to craft synthetic liver tissues that might approach the functionality of a healthy liver. These two chapters collectively lay the foundation for an in-depth exploration of the liver's intricacies, from its structural anatomy to the exciting prospects of engineering liver tissues. Part 2 details our artificial liver project, focusing on developing a large-volume functional liver scaffold comprising three distinct models for two different culture conditions. These models are meticulously designed to explore the influence of cell culture conditions, including both static and dynamic flow conditions. Inspired by previous research, we employed 3D extrusion bioprinting with an inverse-gravity technique and a laminar-flow device to generate these large-volume constructs. To address the challenge of nutrient and oxygen diffusion within large scaffolds, we implemented a pumping system that directly delivers cell culture medium through a hollow channel embedded within the scaffold. Additionally, we conducted investigations into the appropriate material matrix for cell maturation, aiming to mimic the biological environment of native liver tissue and sustain long-term culture. A rigorous biological analysis process was employed to evaluate our models. This process included assessment of cell proliferation, cell viability, liver function through albumin and urea secretion, and examination of cell morphology. This chapter marks significant progress in advancing the field of artificial liver research.