Journal
JOURNAL OF APPLIED TOXICOLOGY
Volume 32, Issue 6, Pages 429-435Publisher
WILEY
DOI: 10.1002/jat.1745
Keywords
hydroxyapatite nanoparticles; osteoblast; inhibition; apoptosis; ROS; p53; cytochrome c
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Funding
- Nanional Natural Science Foundation [30470479]
- Shanghai Sci-Tech Committee Foundation [0752 nm026, 08DZ2291600]
- Shanghai Leading Academic Discipline Project [S30206]
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Hydroxyapatite nanoparticles (nano-HAP) have been reported to cause inflammatory reactions. Here, we aimed to compare the effects of four types of nano-HAP with different nanocrystal morphologies (short rod-like, long rod-like, spherical or needle-shaped crystals) and sizes (10-20, 10-30 or 20-40?nm) on growth inhibition and apoptosis in primary cultured rat osteoblasts. The osteoblasts was treated with the four types of nano-HAP at various concentrations (20, 40, 60, 80 or 100?mg?l-1). The nano-HAP specific surface area was detected using the Brunauer, Emmet and Teller method. The cell growth rate was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay; apoptotic alterations and the level of reactive oxygen species in osteoblasts were measured using flow cytometry; and the amounts of apoptotic p53 and cytochrome c proteins were measured using western blotting. We observed that all four types of nano-HAP inhibited the growth of osteoblasts in a dose-dependent manner. These nano-HAP significantly induced apoptosis in osteoblasts. Nano-HAP with smaller specific surface areas induced lower apoptosis rates. The needle-shaped and the short rod-like particles induced greater cellular injury than the spherical and long rod-like particles, respectively. The increased apoptosis rates were accompanied by increased p53 and cytochrome c expression. These findings indicate that nano-HAP inhibit the activity of osteoblasts and also induce the apoptosis of osteoblasts in vitro. These findings also suggest that the nano-HAP-induced apoptotic pathway is mediated by a mitochondrial-dependent pathway. Moreover, the sizes, morphologies and concentrations of nano-HAP have significant effects on the apoptotic level. Copyright (C) 2011 John Wiley & Sons, Ltd.
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