The desire for repair of tissue defects and injury is the major need prompting research into tissue engineering. Engineering of anisotropic tissues requires production of ordered substrates that orient cells preferentially and support cell viability and differentiation. Towards this goal, this thesis investigated methodologies to align extracellular matrix structures in vitro to guide stem/progenitor cell behaviour for tissue regeneration. Aligned collagen fibrils were deposited on planar substrates from collagen solutions streaming through a microfluidic channel system. Collagen solution concentration, degree of gelation, shear rate and pre-coating of the substrate were demonstrated to determine the orientation and density of the immobilized fibrils. The degree of collagen fibril orientation increased with increasing flow rates of the solution while the matrix density increased at higher collagen solution concentrations and on hydrophobic polymer pre-coatings. Additionally, the length of the immobilized collagen fibrils increased with increasing solution concentration and gelation time. Aligned collagen matrices were refined by incorporating the glycosaminoglycan heparin to study multiple extracellular matrix components in a single system. Multilineage (osteogenic/adipogenic/chondrogenic) differentiation of mesenchymal stem and progenitor cells was maintained by the aligned structures. Most noticeable was the observation that during osteogenesis, aligned collagen substrates choreographed ordered matrix mineralization. Likewise, myotube assembly of C2C12 cells was profoundly influenced by aligned topographic features resulting in enhanced myotube organization and length. Neurites from neural stem cells were highly oriented in the direction of the underlying fibrils. Neurite outgrowth was enhanced on aligned collagen compared to non-aligned collagen or poly-D-lysine substrates, while neural differentiation and cell survival were not influenced by the type of substrate. Using the new method to align collagen type I, the interior walls of cellulose hollow fiber membranes were coated with longitudinally aligned collagen fibrils to fabricate an advanced guidance conduit for nerve regeneration. First cell culture experiments showed that the tubes coated with aligned collagen supported viability and adherence of spinal cord-derived neurospheres. Together, these results demonstrate the feasibility of aligned collagen matrices as a versatile platform to control cell behaviour towards tissue regeneration. Ultimately, the new method to align collagen fibrils and to coat hollow membranes may become an integral component of tissue engineering, working synergistically with other emerging techniques to promote functional tissue replacements.

The desire for repair of tissue defects and injury is the major need prompting research into tissue engineering. Engineering of anisotropic tissues requires production of ordered substrates that orient cells preferentially and support cell viability and differentiation. Towards this goal, this thesis investigated methodologies to align extracellular matrix structures in vitro to guide stem/progenitor cell behaviour for tissue regeneration. Aligned collagen fibrils were deposited on planar substrates from collagen solutions streaming through a microfluidic channel system. Collagen solution concentration, degree of gelation, shear rate and pre-coating of the substrate were demonstrated to determine the orientation and density of the immobilized fibrils. The degree of collagen fibril orientation increased with increasing flow rates of the solution while the matrix density increased at higher collagen solution concentrations and on hydrophobic polymer pre-coatings. Additionally, the length of the immobilized collagen fibrils increased with increasing solution concentration and gelation time. Aligned collagen matrices were refined by incorporating the glycosaminoglycan heparin to study multiple extracellular matrix components in a single system. Multilineage (osteogenic/adipogenic/chondrogenic) differentiation of mesenchymal stem and progenitor cells was maintained by the aligned structures. Most noticeable was the observation that during osteogenesis, aligned collagen substrates choreographed ordered matrix mineralization. Likewise, myotube assembly of C2C12 cells was profoundly influenced by aligned topographic features resulting in enhanced myotube organization and length. Neurites from neural stem cells were highly oriented in the direction of the underlying fibrils. Neurite outgrowth was enhanced on aligned collagen compared to non-aligned collagen or poly-D-lysine substrates, while neural differentiation and cell survival were not influenced by the type of substrate. Using the new method to align collagen type I, the interior walls of cellulose hollow fiber membranes were coated with longitudinally aligned collagen fibrils to fabricate an advanced guidance conduit for nerve regeneration. First cell culture experiments showed that the tubes coated with aligned collagen supported viability and adherence of spinal cord-derived neurospheres. Together, these results demonstrate the feasibility of aligned collagen matrices as a versatile platform to control cell behaviour towards tissue regeneration. Ultimately, the new method to align collagen fibrils and to coat hollow membranes may become an integral component of tissue engineering, working synergistically with other emerging techniques to promote functional tissue replacements.