Fabrication and Osteogenesis of a Porous Nanohydroxyapatite/Polyamide Scaffold with an Anisotropic Architecture

Scaffolds are used in bone tissue engineering to provide a temporary structural template for cell seeding and extracellular matrix formation. However, tissue formation on scaffold outer edges after implantation due to insufficient interconnectivity may restrict cell infiltration and mass transfer to/from the scaffold center, leading to bone regeneration failure. To address this problem, we prepared nanohydroxyapatite/polyamide66 (n-HA/PA66) anisotropic scaffolds with axially aligned channels (300 μm) with the aim to enhance pore interconnectivity and subsequent cell and tissue infiltration throughout the scaffold. Anisotropic scaffolds with axially aligned channels had better mechanical properties and a higher porosity (86.37%) than isotropic scaffolds produced by thermally induced phase separation (TIPS). The channels in the anisotropic scaffolds provided cells with passageways to the scaffold center and thus facilitated cell attachment and proliferation inside the scaffolds. In vivo studies showed that the anisotropic scaffolds could better facilitate new bone ingrowth into the inner pores of the scaffold compared to the isotropic scaffolds. The anisotropic scaffolds also had improved vascular invasion into their inner parts, increasing the supply of oxygen and nutrients to the cells and thus facilitating revascularization and bone ingrowth. Enhanced cell and tissue penetration to the scaffold center was observed in the anisotropic scaffolds both in vitro and in vivo, indicating the axially aligned channels positively influenced cell and tissue infiltration. Thus, such scaffolds have great potential for applications in bone tissue engineering.