Optimized osteogenesis of porcine bone-derived xenograft through surface coating of magnesium-doped nanohydroxyapatite.

As one of the key factors influencing the outcome of guided bone regeneration, the currently used xenografts possess insufficient capability in osteogenesis. With the aim of improving the osteogenic performance of xenografts, porcine bone-derived hydroxyapatite (PHA) was prepared and subsequently coated by magnesium-doped nano hydroxyapatite (nMgHA, 10%, 20%, and 30% of Mg/Ca+Mg) through a straightforward and cost-efficient approach. The physiochemical and biological properties of nMgHA/PHAs were examined in vitro and in vivo. The inherent three-dimensional porous framework with the average pore size of 300 μm was well preserved in nMgHA/PHAs. Meanwhile, excess magnesium released from the so-called 'surface pool' of PHA was verified. In contrast, slower release of magnesium at lower concentrations was detected for nMgHA/PHAs. Significantly more newly-formed bone and microvessels were observed in 20%nMgHA/PHA than the other specimens. With the limitations of the present study, it could be concluded that PHA coated by 20%nMgHA may have the optimized osteogenic performance due to the elimination of the excess magnesium from the 'surface pool', the preservation of the inherent three-dimensional porous framework with the favorable pore size, and the release of magnesium at an appropriate concentration that possessed osteoimmunomodulatory effects on macrophages.