A multi-component biomimetic approach to bone tissue engineering using human mesenchymal stem cells.

摘要

The fate of human mesenchyam stem cells (hMSCs) is determined in large part by microenvironmental cues. Cells respond to these biochemical and biophysical signals through proliferation, specific lineage commitment and differentiation, or apoptosis. Due to the microenvironmental influence on cell fate mimicking the cellular microenvironment has emerged as an important approach to creating functionalized tissue grafts from hMSCs. To mimic natural bone tissue our lab previously developed a biomimetic scaffold composed of hydroxyapatite, chitosan, and gelatin (HCG) that has shown great potential in inducing hMSCs down an osteogenic pathway. The cationic nature of chitosan creates electrostatic interactions with anionic macromolecules including elements of the key extracellular matrix (ECM) proteins and growth factors, making chitosan an important component of composite materials for bone regeneration. The central hypothesis of the current work is that perfusion flow alters the distribution of macromolecules in the chitosan-based scaffolds, thereby influencing hMSC construct development and functional outcome. Chapter 2 of the dissertation reports the impact of perfusion pre-conditioning of 3D porous HCG scaffolds on hMSC construct development. In Chapter 3, the role of media flow on hMSC construct development was investigated using the in-house perfusion bioreactor system. In Chapter 4, the HCG scaffolds were impregnated with BMP-2 plasmid DNA and the impact of scaffold-mediated BMP-2 transfection on hMSC construct development was delineated. Together, the results indicate that perfusion flow effectively modulates construct microenvironment in the HCG scaffolds and is essential in fabricating bone constructs from hMSC. In addition, the osteogenic potential of the hMSC could be further enhanced by incorporating BMP-2 plasmid DNA in the HCG scaffolds.