| One concern in bone tissue engineering is the limited bone ingrowth into scaffolds due to inadequate diffusion of oxygen, nutrients, and waste when cell loaded scaffolds are cultured statically. To overcome limitations associated with static culture, a dynamic culture system using the High Aspect Ratio Vessel (HARV) bioreactor was adopted by our laboratory for bone tissue engineering applications.;This dissertation presented the design, development, and characterization of buoyant poly (lactic-co-glycolic acid) (PLAGA)/nano-hydroxyapatite (n-HA) composite scaffolds for bone tissue engineering applications in HARV bioreactors. Composite microspheres with various PLAGA/n-HA ratios were synthesized and characterized. The 3-dimensional (3D) scaffolds were fabricated via a sintered microsphere method. Mechanical properties of the scaffolds were found to be modulated by sintering conditions and PLAGA/n-HA ratio. After optimization, PLAGA/n-HA (4:1) scaffolds sintered at 90°C for 3 hours exhibited the highest mechanical properties, which were higher than those of pure polymeric scaffolds. The newly developed scaffolds exhibited desirable pore structure and density for applications in HARV bioreactor based bone tissue engineering. The incorporation of n-HA imparted bioactivity to the scaffolds and affected the degradation of scaffolds in aqueous media. The PLAGA/n-HA scaffolds were found to be cytocompatible using both rabbit mesenchymal stem cells (RMSCs) and human mesenchymal stem cells (HMSCs). During in vitro static culture, PLAGA/n-HA scaffolds supported MSC proliferation, phenotypic expression, and calcium deposition into matrix. Finally, the newly developed composite scaffolds were applied in the dynamic culture environment in HARV bioreactors and the cellular behavior of HMSCs was investigated. HMSCs were found to distribute throughout the 3D structure of PLAGA/n-HA scaffolds and exhibited elevated proliferation, differentiation and mineralization on PLAGA/n-HA scaffolds than on PLAGA scaffolds.;The work described in this dissertation presented the successful development of PLAGA/n-HA composite scaffolds with superior physical and biological properties and provided strong evidence on their efficiency in generating cell/scaffold constructs with uniform cell and ECM distribution throughout the 3D structure when cultured with MSCs in HARV bioreactors. This tissue engineering strategy which utilizes PLAGA/n-HA scaffolds with MSCs in HARV bioreactors is promising in generating "engineered" tissue for potential therapeutic applications. |
