Development of polyurethane scaffolds with controlled mechanical strength and inner structure as potential cell/drug delivery system for tissue regeneration
For the application of cell therapy in tissue repair, there is a compelling need for the development of suitable cell carriers, which will function as synthetic analogs of the extracelluar matrix (ECM) that provide a substrate for transplanted cell adhesion, control the localization of the cells in vivo, and serve as a template for the formation of new tissue masses from the combination of transplanted cells and interfacing host cells. Polyurethane can be served as a polymer carrier with adjustable characteristics for multi-purpose usage in cell delivery system. In the meanwhile, the influence of physical properties of polyurethane scaffolds on cell growth and engraftment in the wounded sites is also necessary to be clarified by understanding the molecular mechanism between cell-biomaterial interactions and thus the wound healing process will be able to be optimally controlled by modifying the applied polyurethane properties. The goal of this dissertation was to develop a cell carrier system with tunable physical properties for mesenchymal stem cell delivery to restore tissue function by supplying the multiple factors required for healing from the regenerative stem cells. Two-component polyurethanes were used as the carrier of cell delivery system as well as to help peripheral tissue infiltrate into the defect sites. The mechanical properties of polyurethane are modified by changing the structures of hard and soft segments, which is easily achieved by controlling the chain length of polyol and isocyanate in the reaction, while the structure of the 3D scaffolds were precisely controlled by a new templated-Fused Deposition Modeling (t-FDM) process with the computer aided 3D-printing technique. Cellular response and molecular mechanism were studies in vitro and in vivo. Therefore, a potentially translational cell delivery system with control over cell fate was developed and characterized in the presented dissertation.