Innovative macroporous granules of nanostructured‐hydroxyapatite agglomerates: Bioactivity and osteoblast‐like cell behaviour

Abstract To modulate the biological response of implantable granules, two types of bioactive porous granules composed of nanostructured‐hydroxyapatite (HA) agglomerates and microstructured‐HA, respectively, were prepared using a polyurethane sponge impregnation and burnout method. The resulting granules presented a highly porous structure with interconnected porosity. Both types of granules were characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry. Results showed that nanostructed‐HA granules presented higher surface area and porosity than microstructured‐HA granules. In vitro testing using MG63 human osteoblast‐like cells showed that on both types of surfaces cells were able to adhere, proliferate, and migrate through the macropores, and a higher growth rate was achieved on nanostructured‐HA granules than on microstructured‐HA granules (76 and 40%, respectively). In addition, these cells maintained similar expression levels of osteoblastic‐associated markers namely collagen type I, alkaline phosphatase, bone morphogenetic protein‐2, macrophage colony‐stimulating factor, and osteoprotegerin. These innovative nanostructured‐HA granules may be considered as promising bioceramic alternative matrixes for bone regeneration and drug release application. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.