Development of a biodegradable composite scaffold for bone tissue engineering: Physicochemical, topographical, mechanical, degradation, and biological properties

The development of synthetic materials and their use in tissue engineering applications has attracted much attention in recent years as an option for trabecular bone grafting. Bioabsorbable polyesters of the poly(alpha-hydroxy acids) family, and specifically polylactic acid (PLA), are well known bioabsorbable materials and are currently used for numerous biomedical applications. The incorporation of an inorganic phase, such as a soluble calcium phosphate glass in the P2O5 - CaO - Na2O - TiO2 system, into the polymeric matrix enhances the mechanical integrity of the material. In fact, the flexural elastic modulus increases from 3.2 to 10 GPa with 50 wt/wt% of glass particles. It also improves the biological behavior and modifies the degradation pattern of the polymer. The presence of glass particles accelerates the material degradation and induces the formation of calcium phosphate precipitates in the surface of the composite. Therefore, the combination of a bioabsorbable polymer such as PLA with a soluble calcium phosphate glass leads to a fully degradable composite material with a high bone regenerative potential. The success of a 3D scaffold depends on several parameters that go from the macro- to the nanoscale. The solvent and casting technique, together with particulate leaching, allows the elaboration of 95%-porosity scaffolds with a well interconnected macro- and microporosity. Factors such as surface chemistry, surface energy, and topography can highly affect the cell-material response. Indeed, the addition of glass particles in the PLA matrix modifies the material surface properties such as wettability AI (Area index or real-surface-area/nominal-area ratio) and roughness, improving the cell response and inducing morphological changes in the cytoskeleton of the osteoblasts. This study offers valuable insight into the parameters affecting cell-scaffold behavior, and discusses the special relevance that a comprehensive characterization and manufacturing control of the composite surface can have for monitoring the biological-synthetic interactions.