Centre for Translational Bone, Joint and Soft Tissue Research, Medical Faculty of Technische Universität Dresden and University Hospital Carl Gustav Carus, Fetscher Str. 74, 01307, Dresden, Germany.
J Mater Sci Mater Med. 2013 Jul;24(7):1755-66. doi: 10.1007/s10856-013-4933-2. Epub 2013 Apr 28.
Conventionally sintered hydroxyapatite-based materials for bone repair show poor resorbability due to the loss of nanocrystallinity. The present study describes a method to establish nanocrystalline hydroxyapatite granules. The material was prepared by ionotropic gelation of an alginate sol containing hydroxyapatite (HA) powder. Subsequent thermal elimination of alginate at 650 °C yielded non-sintered, but unexpectedly stable hydroxyapatite granules. By adding stearic acid as an organic filler to the alginate/HA suspension, the granules exhibited macropores after thermal treatment. A third type of material was achieved by additional coating of the granules with silica particles. Microstructure and specific surface area of the different materials were characterized in comparison to the already established granular calcium phosphate material Cerasorb M(®). Cytocompatibility and potential for bone regeneration of the materials was evaluated by in vitro examinations with osteosarcoma cells and osteoclasts. Osteoblast-like SaOS-2 cells proliferated on all examined materials and showed the typical increase of alkaline phosphatase (ALP) activity during cultivation. Expression of bone-related genes coding for ALP, osteonectin, osteopontin, osteocalcin and bone sialoprotein II on the materials was proven by RT-PCR. Human monocytes were seeded onto the different granules and osteoclastogenesis was examined by activity measurement of tartrate-specific acid phosphatase (TRAP). Gene expression analysis after 23 days of cultivation revealed an increased expression of osteoclast-related genes TRAP, vitronectin receptor and cathepsin K, which was on the same level for all examined materials. These results indicate, that the nanocrystalline granular materials are of clinical interest, especially for bone regeneration.
传统的用于骨修复的羟基磷灰石基材料由于纳米晶的损失而表现出较差的可吸收性。本研究描述了一种建立纳米晶羟基磷灰石颗粒的方法。该材料是通过含有羟基磷灰石 (HA) 粉末的藻酸盐溶胶的离子凝胶化制备的。随后在 650°C 下热消除藻酸盐得到未烧结但出乎意料地稳定的羟基磷灰石颗粒。通过向藻酸盐/HA 悬浮液中添加硬脂酸作为有机填料，颗粒在热处理后表现出大孔。通过在颗粒上额外涂覆硅粒子，得到了第三种材料。对不同材料的微观结构和比表面积与已建立的颗粒状磷酸钙材料 Cerasorb M(®)进行了比较。通过体外与骨肉瘤细胞和破骨细胞的检测评估了材料的细胞相容性和骨再生潜力。成骨样 SaOS-2 细胞在所有检测的材料上增殖，并在培养过程中表现出碱性磷酸酶 (ALP) 活性的典型增加。通过 RT-PCR 证明了材料上编码 ALP、骨粘连蛋白、骨桥蛋白、骨钙素和骨唾液蛋白 II 的骨相关基因的表达。将人单核细胞接种到不同的颗粒上，并通过测定抗酒石酸酸性磷酸酶 (TRAP) 的活性来检测破骨细胞的生成。培养 23 天后的基因表达分析显示，破骨细胞相关基因 TRAP、纤连蛋白受体和组织蛋白酶 K 的表达增加，所有检测材料的表达水平相同。这些结果表明，纳米晶颗粒材料具有临床应用价值，特别是在骨再生方面。
