Date of Award
Doctor of Engineering
Biomedical Engineering, Biomedical Research, Chemical Engineering, Materials Science, Nanoscience
Hepatocellular carcinoma (HCC) is an invasive and aggressive cancer of the liver that arises due to chronic cirrhosis. Research into understanding HCC has focused on two-dimensional (2D) and three-dimensional (3D) technologies to simulate the liver microenvironment and use animal models to model how HCC affects the rest of the body. 3D hydrogel models are desired because they can mimic the transport behavior observed in vivo by structurally mimicking the extracellular matrix (ECM) without the ethical concerns of animal models. However, hydrogels can be toxic to cells and require optimal procedures for appropriate handling. In this study, we created 3D models of liver diseases on high-throughput platforms. First, we optimized hydrogel attachment on micropillar chips by coating them with 0.01 w/v % PMA-OD in ethanol. Next, we optimized the protocol for encapsulation of viable Hep3B cells PuraMatrix peptide hydrogel, using a higher seeding density (6 * 106 cells/mL) and two post-print media washes. Then, we established the ability to transduce adenoviruses in situ in encapsulated cells and successfully demonstrated their dose-response behavior towards six compounds. In the second part, we scaled up to using the microwell chip platform and optimized the polymerization of oxidized methacrylated alginate (OMA) for Hep3B encapsulation. First, we plasma-treated microwell chips for 15 minutes at high RF to minimize bubbles. Then, we optimized micro-scale photopolymerization conditions at 45 % methacrylated OMA (OMA-45) and 2 w/v % OMA with 0.05 w/v % PI and reflective background under either low intensity, long duration (2.5 mW/cm2 for 2 minutes) or high intensity, short duration (4.0 mW/cm2, 30 seconds) light by testing cell viability at these conditions. Third, we used these OMA conditions to develop a high-throughput, real-time 3D cell migration assay on a newly engineered 384-pillar plate with sidewalls. We first developed a set of a protocols where out-of-focus cells are removed mean position of cells on a pillar are quantified. Next, we established a delay in growth factor release rate by co-encapsulating growth factors with OMA and methacrylated heparin sulfate sulfate (MH). Finally, we demonstrated collective cell migration occurred toward angiogenic growth factors at 6-10 μm/day over two weeks. These results provide optimized chemistry between hydrogels and polystyrene, show effective hydrogel polymerization techniques for microscale tissue engineering, and yield several methods where scientists can model liver diseases in high-throughput.
Roth, Alexander David, "Modeling Liver Diseases Using Hepatic Cell Microarrays" (2018). ETD Archive. 1110.