García A J, Ducheyne P, Boettiger D
Department of Bioengineering, University of Pennsylvania, Philadelphia 19104, USA.
J Biomed Mater Res. 1998 Apr;40(1):48-56. doi: 10.1002/(sici)1097-4636(199804)40:1<48::aid-jbm6>3.0.co;2-r.
Bioactive glasses and ceramics enhance bone formation and bond directly to bone, and have emerged as promising substrates for bone tissue engineering applications. Bone bioactivity involves physicochemical surface reactions and cellular events, including cell attachment to adsorbed extracellular matrix proteins. The effects of fibronectin (Fn) adsorption and glass surface reaction stage on the attachment of osteoblast-like cells (ROS 17/2.8) to bioactive glass were analyzed. Bioactive glass disks were pretreated in a simulated physiologic solution to produce three reaction layers: unreacted glass (BG0), amorphous calcium phosphate (BG1d), and carbonated hydroxyapatite (BG7d). Synthetic hydroxyapatite (sHA) and nonreactive borosilicate glass (CG) were used as controls. A spinning disk device which applied a linear range of forces to attached cells while maintaining uniform chemical conditions at the interface was used to quantify cell adhesion. The number of adherent cells decreased in a sigmoidal fashion with applied force, and the resulting detachment profile provided measurements of adhesion strength. For the same amount of adsorbed Fn, cell adhesion was higher on surface-reacted bioactive glasses (BG1d and BG7d) than on BG0, CG, and sHA. For all substrates, cell attachment was primarily mediated by the RGD binding site of Fn, as demonstrated by blocking experiments with antibodies and RGD peptides. Cell adhesion strength increased linearly with adsorbed Fn surface density. Analysis of this fundamental relationship revealed that improved adhesion to reacted bioactive glasses resulted from enhanced cell receptor-Fn interactions, suggesting substrate-dependent conformational changes in the adsorbed Fn.
生物活性玻璃和陶瓷可促进骨形成并直接与骨结合，已成为骨组织工程应用中有前景的基质。骨生物活性涉及物理化学表面反应和细胞事件，包括细胞附着于吸附的细胞外基质蛋白。分析了纤连蛋白（Fn）吸附和玻璃表面反应阶段对成骨样细胞（ROS 17/2.8）附着于生物活性玻璃的影响。生物活性玻璃圆盘在模拟生理溶液中预处理以产生三个反应层：未反应的玻璃（BG0）、无定形磷酸钙（BG1d）和碳酸羟基磷灰石（BG7d）。合成羟基磷灰石（sHA）和非反应性硼硅酸盐玻璃（CG）用作对照。使用一种旋转圆盘装置，该装置在保持界面化学条件均匀的同时对附着细胞施加线性范围的力，以量化细胞粘附。随着施加力的增加，贴壁细胞数量呈S形减少，由此产生的脱离曲线提供了粘附强度的测量值。对于相同量的吸附Fn，表面反应的生物活性玻璃（BG1d和BG7d）上的细胞粘附高于BG0、CG和sHA上的细胞粘附。对于所有基质，细胞附着主要由Fn的RGD结合位点介导，这通过抗体和RGD肽的阻断实验得到证明。细胞粘附强度随吸附的Fn表面密度线性增加。对这种基本关系的分析表明，对反应性生物活性玻璃的粘附改善是由于细胞受体与Fn相互作用增强，这表明吸附的Fn存在底物依赖性构象变化。
