Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, People’s Republic of China.
Int J Nanomedicine. 2012;7:1239-50. doi: 10.2147/IJN.S28098. Epub 2012 Mar 7.
Hydroxyapatite (HA) is the principal inorganic constituent of human bone. Due to its good biocompatibility and osteoconductivity, all kinds of HA particles were prepared by different methods. Numerous reports demonstrated that the properties of HA affected its biological effects.
Two kinds of nanohydroxyapatite with different sizes and crystallinities were obtained via a hydrothermal treatment method under different temperatures. It was found that at a temperature of 140°C, a rod-like crystal (n-HA1) with a diameter of 23 ± 5 nm, a length of 47 ± 14 nm, and crystallinity of 85% ± 5% was produced, while at a temperature of 80°C, a rod-like crystal (n-HA2) with a diameter of 16 ± 3 nm, a length of 40 ± 10 nm, and crystallinity of 65% ± 3% was produced. The influence of nanohydroxyapatite size and crystallinity on osteoblast viability was studied by MTT, scanning electron microscopy, and flow cytometry.
n-HA1 gave a better biological response than n-HA2 in promoting cell growth and inhibiting cell apoptosis, and also exhibited much more active cell morphology. Alkaline phosphatase activity for both n-HA2 and n-HA1 was obviously higher than for the control, and no significant difference was found between n-HA1 and n-HA2. The same trend was observed on Western blotting for expression of type I collagen and osteopontin. In addition, it was found by transmission electron microscopy that large quantities of n-HA2 entered into the cell and damaged the cellular morphology. Release of tumor necrosis factor alpha from n-HA2 was markedly higher than from n-HA1, indicating that n-HA2 might trigger a severe inflammatory response.
This work indicates that not all nanohydroxyapatite should be considered a good biomaterial in future clinical applications.
羟基磷灰石（HA）是人体骨骼的主要无机成分。由于其良好的生物相容性和骨传导性，各种 HA 颗粒通过不同的方法制备。大量报道表明，HA 的性质影响其生物效应。
通过在不同温度下的水热处理方法获得两种具有不同尺寸和结晶度的纳米羟基磷灰石。结果发现，在 140°C 时，生成了一种直径为 23±5nm、长度为 47±14nm、结晶度为 85%±5%的棒状晶体（n-HA1）；而在 80°C 时，生成了一种直径为 16±3nm、长度为 40±10nm、结晶度为 65%±3%的棒状晶体（n-HA2）。通过 MTT、扫描电子显微镜和流式细胞术研究了纳米羟基磷灰石的尺寸和结晶度对成骨细胞活力的影响。
n-HA1 在促进细胞生长和抑制细胞凋亡方面比 n-HA2 产生更好的生物学反应，并且表现出更活跃的细胞形态。两种 n-HA2 和 n-HA1 的碱性磷酸酶活性明显高于对照组，且 n-HA1 和 n-HA2 之间无显著差异。I 型胶原和骨桥蛋白的 Western 印迹结果也呈现相同的趋势。此外，透射电子显微镜观察发现大量的 n-HA2 进入细胞并破坏了细胞形态。n-HA2 释放的肿瘤坏死因子-α明显高于 n-HA1，表明 n-HA2 可能引发严重的炎症反应。
本研究表明，在未来的临床应用中，并非所有纳米羟基磷灰石都应被视为良好的生物材料。
