In Vitro and In Vivo Evaluations of 3D Porous TCP-coated and Non-coated Alumina Scaffolds

Abstract

Both tricalcium phosphate (TCP) and alumina have been extensively studied and shown to have high biocompatibility. Tricalcium phosphate has improved biodegradability and a higher solubility than hydroxyapatite. In contrast, alumina (Al₂O₃) is almost completely inert at physiological conditions and has been used as a biomaterial due to its wear resistance, high surface finish, and excellent hardness. Thus, the combination of these two implants would result in greater biocompatibility and phenotype maintenance. A polyurethane (PU) foam replica method was employed in this study to coat TCP on an alumina scaffold. The TCP-coated alumina scaffold was then sintered to generate a porous surface morphology. The pore sizes obtained using this approach ranged between 100—600 µm, which is ideal for cellular proliferation. The cytotoxicity, cellular proliferation, differentiation, and ECM deposition on the coated scaffold resulted in longer-term viability of osteogenic markers compared to the non-coated scaffold. Moreover, the osteogenic properties of porous TCP-coated Al₂O₃ scaffolds were reported in this study using rabbit models. The TCP/Al₂O ₃ scaffold and control Al₂O₃ scaffolds were implanted in the rabbit femur. The bone tissue response was analyzed with micro-computed tomography (micro CT) at 12 and 24 weeks after implantation. The porous scaffolds exhibited favorable hard and soft tissue responses at both time points. At 24 weeks, a three-fold increase in bone tissue ingrowth was observed in defects containing TCP-coated Al₂O₃ scaffolds compared to control Al₂O₃ scaffolds.