Tissue engineering in bone defects: Development of porous copolymer scaffolds stimulating stem cell growth and bone regeneration

For repair of bone defects, tissue engineering would be to combine cells capable of osteogenic activity with an appropriate scaffold. Mesenchymal stem cells are multipotential cells that are capable of differentiating into different type of cells dependin g on culture condition. The selection of the most appropriate material to produce a scaffold is an important step towards construction of a tissue engineered product. The commonly used biodegradable polymers, have a drawback of their high hydrophobicity a nd low hydrophilicity resulting in a slow hydrolytic degradation rate and therefore affecting long-term biocompatibility. To develop the second generation of bioresorabable copolymers which is aimed to result from this project, scaffolds are prepared by c opolymerization of L-lactide (LLA) and 1,5-dioxepan-2-one or LLA and caprolactone monomers. By controlling hydrophilicity and surface nano/microstructure, these copolymers can be good candidates as scaffolds and it may also be possible to encourage and op timize growth of cells within the artificial structure. Recent reports showed that the developed scaffolds retained good mechanical properties and high elasticity with controlled tensile properties during several weeks of degradation. Bone marrow mesenchy mal stem cells and human osteoblasts are isolated from patients undergoing routine surgery, cultured and induced to differentiate in osteogenic culture conditions. Thereafter, cells will be grown on the scaffolds to determine the optimal porosity for cell adhesion, protein adsorption and expression of ECM. Cell attachment to the scaffolds and cell sensing and location within the pores are observed using AFM and SEM. Furthermore, cell proliferation capacity, their osteogenic potentials and gene expression profile and production of local factors are evaluated. After determining the optimal scaffolds in cultures models, the scaffolds with or without cells will be implanted for histological analysis in animal models.