羟基磷灰石球形颗粒表面微形貌构建及其对干细胞生物学行为的调控

通过调节溶胶-凝胶体系中羟基磷灰石(HA)粉末和甲壳素(Chitin)的质量比, 制备具有不同表面微形貌的HA球形颗粒。扫描电子显微镜(SEM)表征结果显示: 随着HA/Chitin质量比从4/1增加到35/1, 球形颗粒的表面微形貌发生了明显变化, 由粗糙渐趋平滑, 微米级皱褶逐渐减少至消失, 微孔隙率从(35%±0.8%)减少到(10.4%±0.7%)。体外细胞培养的结果表明具有微米级皱褶, 微孔隙率较高的粗糙表面具有引导干细胞铺展和增殖的作用, 微孔隙率低的平滑表面则具有引导干细胞轴向延伸及骨向分化的趋势。同时, HA球形颗粒表面微形貌对干细胞表面特征性抗原标志物的表达具有调控作用。

Surface Microstructure on Hydroxyapatite Spherules and Its Regulation on Stem Cells

HA spheres with different surface microstructures were prepared by a Sol-Gel route with various hydroxyapatite (HA)/chitin ratios. The surface morphologies, phase compositions, and biomimetic mineralization ability of samples were respectively analyzed with scanning electron microscopy (SEM), X-ray diffraction (XRD), and biomimetic mineralization test. Furthermore, the influences of the surface microstructure on biological behavior of bone marrow-derived mesenchymal stem cells were examined by Alamar blue, SEM, alkaline phosphatase assay and flow cytometry. When the mass ratio of HA/Chitin was increased from 4/1 to 35/1, the surface microstructure of HA spheres changed substantially, as showed by a reduction of micro-porosity from (35%±0.8%) to (10.4%±0.7%), decrease of surface roughness, and gradual disappearance of micro-creases. The result of biomimetic mineralization test showed that the surface microstructure had important influence to the ability of biomimetic mineralization for HA spheres. In vitro culture of bone marrow-derived mesenchymal stem cells demonstrated that the rougher sphere surface, with abundant micro-creases and micro-pores, supported cell spreading and proliferation. In comparison, the smoother sphere surface with fewer micro-pores effectively induced cell elongation and up-regulated ALP expression, which suggested stem cells osteogenic differentiation. Meanwhile, the surface microstructure of spherules also modulated the expression of characteristic antigen makers on the surface of stem cells.