Adams Brandy R, Mostafa Amany, Schwartz Zvi, Boyan Barbara D
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia.
J Biomed Mater Res A. 2014 Sep;102(9):3237-42. doi: 10.1002/jbm.a.34994. Epub 2013 Oct 28.
Normal bone mineral is a carbonated-apatite, but there are limited data on the effect of mineral containing carbonate on cell response. We characterized surface chemical compositions of three experimental carbonated hydroxyapatite (CO3(2-) HA) substrates and investigated their effect on osteoblast differentiation. Carbonate was incorporated into the hydroxyapatite powders while phosphate and hydroxyl groups were shown to be reduced by analyzing the chemical composition of the substrate surfaces. CO3(2-) HA powders with increasing carbonate concentrations designated as C1 (3.88%), C2 (4.85%), and C3 (5.82%) were molded, pressed, and fired into 14 mm discs. We observed that calcium phosphate ratios increased monotonically with increasing carbonate content, whereas differentiation of MG63 cells decreased. CO3(2-) HA surfaces also affected factor production. Addition of carbonate caused a 70% reduction in osteoprotegerin (OPG) compared to cultures on pure HA, but the effect of carbonate was not dose-dependent. Low carbonate content reduced VEGF-A by 80%, but higher levels of carbonate reversed this effect in a concentration dependent manner, with the C3 VEFG-A levels approximately twice that of C1 levels. These observations collectively indicate that bone cells are sensitive to carbonate content in bone mineral and the effects of carbonate substitution vary with the outcome being measured. Overall, this study provides a preliminary understanding of how carbonate substitution within hydroxyapatite modulates cellular behavior.
正常骨矿物质是一种碳酸磷灰石，但关于含碳酸盐矿物质对细胞反应影响的数据有限。我们对三种实验性碳酸羟基磷灰石（CO3(2-) HA）底物的表面化学成分进行了表征，并研究了它们对成骨细胞分化的影响。通过分析底物表面的化学成分，发现碳酸盐被掺入到羟基磷灰石粉末中，同时磷酸根和羟基有所减少。将碳酸盐浓度递增的CO3(2-) HA粉末分别命名为C1（3.88%）、C2（4.85%）和C3（5.82%），经过模塑、压制和烧制制成14毫米的圆盘。我们观察到磷酸钙比率随碳酸盐含量的增加而单调增加，而MG63细胞的分化则减少。CO3(2-) HA表面也影响因子的产生。与在纯HA上培养相比，添加碳酸盐导致骨保护素（OPG）减少70%，但碳酸盐的影响不具有剂量依赖性。低碳酸盐含量使血管内皮生长因子A（VEGF-A）减少80%，但较高水平的碳酸盐以浓度依赖的方式逆转了这种影响，C3的VEGF-A水平约为C1水平的两倍。这些观察结果共同表明，骨细胞对骨矿物质中的碳酸盐含量敏感，并且碳酸盐替代的影响因所测量的结果而异。总体而言，本研究初步了解了羟基磷灰石中的碳酸盐替代如何调节细胞行为。
