Interactions between Cells and Bio- based materials: from Quantitative Analysis to 3D-printed Scaffolds for Medical Applications

Abstract

The aim of this thesis work was to understand the interactions between plant-derived cellulose nanofibrils (CNF) and human living cells and to apply this knowledge to develop 3D printed scaffolds. These 3D scaffolds have the potential in solving organ crisis issues and replacing animal models for drug screening. A protocol to use colloidal probe microscopy (CPM), a technique based on atomic force microscopy, to easure the interactions between biomaterials (CNF and laminin 521) and living cells as successfully established. Both hepatocellular carcinoma cell line HepG2 and human pluripotent stem cell line WAo7 were studied. It was found that, in contrast to the strong adhesion between laminin and living cells, CNF demonstrated a lower affinity for both HepG2 cells and WAo7 cells. It was moreover found that the interaction between laminin 521 and cells was integrin regulated, while the interaction between CNF and cells was nonspecific and not mediated by integrins. Furthermore, correlation a found between the adhesion energy and successful two- dimensional (2D) cell culture results. Neither HepG2 cells nor WAo7 cells grew on CNF films, but on the laminin 521 films, indicating that a certain magnitude of adhesion energy is required to induce cell growth. Surface plasmon resonance (SPR) was applied in order to further investigate the effect of laminin and another commonly used protein, poly-l-lysine (PLL), as well as other cell culture components, on cell affinity for CNF films. Coating CNF with either laminin 521 or PLL was found to significantly enhance the cell adsorption. To build CNF-based, three-dimensional (3D) cell culture models, 3D printing technique was used to fabricate 3D scaffolds. The combination of, on the one hand, highly charged TEMPO-CNF and galactoglucomannan methacrylates (GGMMAs), and, on the other hand, native, low-charged CNF and alginate together with spherical colloidal lignin particles (CLPs) were both investigated. The TEMPO-CNF/GGMMAs scaffolds exhibited a wide mechanical strength range depending on the degree of crosslinking, which could be controlled by changing the amount and the degree of substitution of GGMMA. On the other hand, CLPs were able to increase the printing resolution and add antioxidant properties to the CNF-alginate-CLPs scaffolds. Both the TEMPO-CNF/GGMMAs and the CNF-alginate-CLPs scaffolds demonstrated excellent shape fidelity and biocompatibility, indicating great potential in biomedical applications.