Development of a Biodegradable Composite Scaffold for Bone Tissue Engineering: Physicochemical, Topographical, Mechanical, Degradation, and Biological Properties

Abstract

The development of synthetic materials and their use in tissue engineering applications hasattracted much attention in recent years as an option for trabecular bone grafting. Bioabsorbablepolyesters of the poly(α-hydroxy acids) family, and specifically polylactic acid (PLA), are wellknown bioabsorbable materials and are currently used for numerous biomedical applications. The incorporationof an inorganic phase, such as a soluble calcium phosphate glass in the P₂O₅ − CaO − Na₂O − TiO₂system, into the polymeric matrix enhances the mechanical integrity of the material. In fact, theflexural 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. Thepresence of glass particles accelerates the material degradation and induces the formation of calciumphosphate precipitates in the surface of the composite. Therefore, the combination of a bioabsorbablepolymer such as PLA with a soluble calcium phosphate glass leads to a fully degradable compositematerial with a high bone regenerative potential. The success of a 3D scaffold dependson 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 wellinterconnected macro- and microporosity. Factors such as surface chemistry, surface energy, and topographycan highly affect the cell-material response. Indeed, the addition of glass particles in the PLAmatrix modifies the material surface properties such as wettability AI (Area index or real-surface-area/nominal-arearatio) and roughness, improving the cell response and inducing morphological changes in the cytoskeletonof the osteoblasts. This study offers valuable insight into the parameters affecting cell-scaffoldbehavior, and discusses the special relevance that a comprehensive characterization and manufacturingcontrol of the composite surface can have for monitoring the biological–synthetic interactions.