Three-Dimensional Porous Scaffolds for Bone Tissue Engineering and Cancer Research Applications
Florczyk, Stephen Joseph
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Tissue engineering constructs (TEC) are comprised of cells, porous biomaterial scaffold, and growth factors to regenerate tissues. The biomaterial scaffold is an essential component of a TEC, substituting for extracellular matrix (ECM), allowing cell adhesion, and providing mechanical support. The drawbacks of scaffolds for tissue engineering include lack of resemblance to the native ECM, lack of mechanical properties, and poor cell delivery and distribution. This dissertation presents the preparation and evaluation of three-dimensional (3D) porous biomaterial scaffolds for bone tissue engineering (BTE) applications. The use of alginate gel to enhance cell seeding of ceramic scaffolds was demonstrated. The alginate gel-seeded constructs had increased cell populations in vitro and enhanced osteogenesis in vivo compared to conventionally seeded samples. The processing of 3D porous chitosan-alginate (CA) scaffolds was examined by varying processing parameters. Solution viscosity had the greatest effect on pore morphology, and scaffolds with uniform pore morphology had the greatest compressive strength and osteoblast proliferation. Through process control, CA scaffolds of differing polymer concentration and pore size were prepared and evaluated with mechanical testing and osteoblast culture. These tests confirmed that the 4 wt% CA scaffolds provided the best combination of pore size and mechanical properties for BTE. The 3D porous CA scaffolds were evaluated in rat calvarial defects for bone regeneration with different treatments and compared to untreated control defects. After 16 weeks, the CA scaffold samples all showed greater bone regeneration than did the control. Additionally, CA scaffolds were investigated for cancer research applications. Tissue engineering approaches recently have been applied to cancer research. 3D cultures better recreate the native tumor microenvironment than do 2D tissue culture plates, which are predominantly used for cancer research. 3D porous CA scaffolds were evaluated for enrichment of cancer stem cell population of human glioblastoma cells and demonstrated greater enrichment than did control samples. 3D porous CA scaffolds were also evaluated for use as an in vitro platform for co-culturing prostate cancer cells with immune cells. The CA scaffolds demonstrated potential for in vitro testing of immunotherapies. The 3D porous CA scaffolds provide a good 3D environment for tissue engineering and cancer applications.