Department of Civil Engineering, North Dakota State University, Fargo, ND 58105, USA.
Acta Biomater. 2011 Mar;7(3):1173-83. doi: 10.1016/j.actbio.2010.10.028. Epub 2010 Oct 26.
The ultimate goal of bone tissue engineering is to develop bony tissues on tissue engineered constructs that mimic the native bone. Nanoscale characterization of in vitro generated bony tissues on engineered scaffolds is essential to understanding both the physical and mechanical characteristics of the engineered bone. Bone nodule formation, a typical early indicator of bone formation was observed on chitosan-polygalacturonic acid-hydroxyapatite (Chi-PgA-HAP) nanocomposite films without the use of differentiating media. Thus, the Chi-PgA-HAP substrates designed are osteoinductive and provide an appropriate microenvironment for cell organization and tissue regeneration. Imaging using atomic force microscopy revealed several levels of hierarchical structures of bone in the bone nodules, consisting of mineralized collagen fibers, fibrils and mineral deposits in extrafibrillar spaces. The nanoscale elastic properties of the collagen and mineral crystals were found to be in close agreement with the experimental and simulations results on natural bone reported in the literature. Fourier transform infrared spectroscopy experiments indicate the presence of collagen and biological apatite in bone nodules exhibiting the characteristics of newly precipitated, immature bone. Collectively, our structural, chemical, and mechanical analyses support the conclusion that synthetic bone nodules mimic the hierarchy of natural bone.
骨组织工程的最终目标是在组织工程支架上开发出类似于天然骨的骨组织。对工程支架上体外生成的骨组织进行纳米级表征对于理解工程骨的物理和机械特性至关重要。在没有使用分化培养基的情况下，壳聚糖-聚半乳糖醛酸-羟基磷灰石（Chi-PgA-HAP）纳米复合材料薄膜上观察到骨结节的形成，这是骨形成的典型早期指标。因此，设计的 Chi-PgA-HAP 基底具有成骨性，并为细胞组织和组织再生提供了适当的微环境。原子力显微镜成像显示，骨结节中的骨具有几个层次的结构，包括矿化胶原纤维、原纤维和纤维外空间中的矿物质沉积物。发现胶原和矿晶体的纳米级弹性性质与文献中报道的天然骨的实验和模拟结果非常吻合。傅里叶变换红外光谱实验表明，骨结节中存在胶原和生物磷灰石，表现出新沉淀的、不成熟骨的特征。总的来说，我们的结构、化学和机械分析支持这样的结论，即合成骨结节模拟了天然骨的层次结构。
