Reconstruction of Large Bone Defects Using 3D-Printed PLGA/TCP Scaffolds: In Vitro and In Vivo Study

Objectives: Complex bone defects present surgeons with frequent reconstructive challenges. 3D printing technology can advance solutions to address the issues of customization through designs that are patient-specific. In this study, 3D-prinetd poly (lactic-co-glycolic acid) (PLGA)/ beta-tricalcium phosphate (β-TCP) composite scaffolds have been designed, fully characterized in vitro, and the in vivo study has been performed in the rabbit large calvaria defect model.
Methods: The PLGA/β-TCP composite was made via the solvent casting method and printed using a 3D-Bioplotter® machine (envisionTEC, Manufacturer Series, Germany). Physico-mechanical and biological properties of the 3D-prinetd scaffolds were evaluated. Laser Measuring Microscope (LEXT OLS4000 3D) and a scanning electron microscopy (SEM) were employed for imaging of the microstructure of the scaffolds. The compressive strength and thermal properties of the designed scaffolds were measured based on mechanical testing and differential scanning calorimetry (DSC) methods, respectively. The in vitro biological characteristics of the scaffolds including cellular adhesion and proliferation as well as bioactivity were studied. Finally, the 3D-printed PLGA/TCP scaffolds were implanted in vivo to evaluate its regeneration function in rabbits’ calvaria defects (1.2 cm).
Results: The microstructural characterization of the scaffolds revealed pore size in the range of 400-500 µm and 60% approximate porosity. 3D-printed PLGA/TCP scaffolds presented mechanical properties comparable with spongy bone. Based on the DSC analysis, the glass transition temperature of PLGA is increased at the presence of TCP, which suggests well dispersion of the inorganic phase. The obtained results from in vitro cellular examinations revealed the improved proliferation of the cells on PLGA/TCP scaffolds compared to the corresponding PLGA matrices. The in vivo results confirmed that the implanted scaffolds in rabbit calvaria defects facilitated new bone tissue formation.
Conclusions: The obtained physico-mechanical, in vitro and in vivo results converge to indicate that the designed PLGA/TCP scaffolds have potential in bone regeneration for critically-size bone defects.