Cells in multicellular organisms are surrounded by a complex three-dimensional macromolecular extracellular matrix (ECM). This matrix, traditionally thought to uniquely serve a structural function providing support and strength to cells within tissues, is increasingly being recognized to have pleiotropic effects in neurogenesis and regeneration processes such as neocortex folding, stem cell niche maintenance, peripheral nerve regeneration, axonal growth, and many more. ECM mediates these processes via cell-ECM interactions which provide the cells with a wealth of signals including biophysical and mechanical cues in a spatiotemporal manner. Owing to the importance of the surrounding microenvironment, modern neural tissue engineering strategies have focused on the development of engineered biomaterials capable of finely instructing the neuronal response according to their physicochemical characteristics. Neurons and neural stem cells are in fact sensitive to their mechanical and topographical environment, and cell–substrate binding contributes to this sensitivity by activating specific signaling pathways for basic cell function. In addition, the advances in nanotechnology have opened the possibility of introducing decorative nano-motifs that interact with cells at the molecular level. Successful strategies in tissue engineering are driven by not only advances in the synthesis of highly instructive biomaterials but also greatly depend on the right selection of cell sources. As a matter of fact, advances in neural tissue engineering have been strongly hampered by the poor availability of cell sources, considering that primary neurons are the only type of cells that do not proliferate. The discovery of induced pluripotent stem cells (iPSCs) has addressed many of the cell-related limitations in neural tissue engineering, offering the possibility to consistently produce a wide range of neural cell lines. Advances in cell biology have led to the development of iPSCs-derived brain spheroid, which surely represent the most promising tools for several neural tissue engineering applications ranging from in vitro modelling of neurodegenerative diseases (i.e., Parkinson's, Huntington's and Alzheimer's), biomaterials testing and drug screening platforms.
The overarching goal of my doctoral work was to engineer biomaterials with instructive physicochemical properties to elicit beneficial cellular responses that are suitable for different neural tissue engineering applications such as nerve regeneration and 3D in vitro modelling.
In the first study (Chapter 2), I evaluated the compounded effects of surface stiffness and micro-topography on dorsal root ganglion and human bone-marrow mesenchymal stem cells behavior. To this end, arrays of parallel microchannels of different geometries were introduced on the surface of chitosan films by electrophoretic replica deposition. In addition, a novel chemical crosslinking with citric acid was performed to both enhance the long-term stability of the chitosan films and fine-tune the surface stiffness for the investigation of its role in cell behavior.
In the second study (Chapter 3), I developed a novel nanocomposite consisting of a collagen hydrogel decorated with glycine-derived carbon nanodots (Gly-CNDs). After a comprehensive physicochemical characterization of the resulting nanocomposite, I evaluated the effects exerted on neuronal differentiation and electrophysiological maturation of mouse iPSCs-derived brain spheroid.
In the third study (Chapter 4), I optimized an alignable collagen-based hydrogel characterized by anisotropically oriented fibers with potential applications in both peripheral and central nervous system repair. I established a protocol that encompasses the introduction in the collagen solution of biodegradable laminin-functionalized magnetic microbeads and the time-controlled application of an external magnetic field. The regenerative potential of the hydrogel was unveiled using mouse iPSCs-derived neural stem cells.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/45821 |
| Date | 10 January 2024 |
| Creators | Lomboni, David |
| Contributors | Variola, Fabio |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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