The Development of a Vascularized Liver-on-a-Chip Using Precise Hydrogel Micro-patterning Techniques

Abstract

This thesis presents the development and validation of a novel in vitro vascularized liver spheroid. The device improved upon two micropatterning techniques previously developed in our lab: extrusion-based 3D printing to create sacrificial scaffolds to form a vascular channel, and microcontact printing using a stamp to imprint a scaffold on the surface of the hydrogel. This study redesigned the stamp to facilitate the precise positioning of hepatic spheroids of varying sizes within a fibrin hydrogel. Furthermore, a novel bifurcating vascular channel scaffold was designed to surround the embedded hepatic spheroid. Functional validation of vascular integrity was conducted using dextran permeability assays to demonstrate the successful restriction of macromolecule leakage for multiple weeks. Furthermore, the vascular network exhibited increased permeability and angiogenesis in the presence of hepatic spheroids. We also determined the optimal media composition and procedure to culture spheroids made of primary hepatocytes. Incorporation into the Angioplate demonstrated improved functional output of the primary hepatic spheroids compared to static conditions revealed through measurements of albumin secretion. The bifurcating Angioplate offers the advantage in cost-effectiveness, scalability, and adaptability to vascularize spheroids. Further studies integrating additional relevant cell types, refining vascular stability, and incorporating automation methods for device assembly will enhance the reliability and potential for the platform in becoming a powerful tool for preclinical drug testing.