Center for Structural and Functional Materials, University of Louisiana at Lafayette, Lafayette, LA 70504, USA.
Acta Biomater. 2010 Jul;6(7):2826-35. doi: 10.1016/j.actbio.2009.12.017. Epub 2010 Jan 4.
Our recent electron microscopy study on biomimetic nanostructured coatings on nanograined/ultrafine-grained (NG/UFG) substrates [Mater Sci Eng C 2009;29:2417-27] indicated that electrocrystallized nanohydroxyapatite (nHA) on phase-reversion-induced NG/UFG substrates exhibited a vein-type interconnected and fibrillar structure that closely mimicked the hierarchical structure of bone. The fibrillar structure on NG/UFG substrate is expected to be more favorable for cellular response than a planar surface. In contrast, hydroxyapatite (HA) coating on coarse-grained (CG) substrate more closely resembled a film rather than a fibrillar structure. Inspired by the differences in the structure of HA coating, we describe here the cell-substrate interactions of pre-osteoblasts (MC 3T3-E1) on bioactive NG/UFG and CG austenitic stainless steel substrates. NG/UFG austenitic stainless steel was obtained by a novel controlled phase-reversion annealing of cold-deformed austenite. This example provides an illustration of how a combination of cellular and molecular biology, materials science and engineering can advance our understanding of cell-substrate interactions. Interestingly, the cellular response of nanohydroxyapatite (nHA)-coated NG/UFG substrate demonstrated superior cytocompatibility, improved initial cell attachment, higher viability and proliferation, and well-spread morphology in relation to HA-coated CG substrate and their respective uncoated (bare) counterparts as implied by fluorescence and electron microscopy and MTT assay. Similar conclusions were derived from an immunofluorescence study that involved examination of the expression levels of vinculin focal adhesion contacts associated with dense actin stress fibers and fibronectin, protein analysis through protein bands in SDS-PAGE, and quantitative total protein assay. The enhancement of cellular response followed the sequence: nHA-coated NG/UFG>nHA-coated CG>NG/UFG>CG substrates. The outcomes of the study are expected to counter the challenges associated with the engineering of nanostructured surfaces with specific physical and surface properties for medical devices with significantly improved cellular response.
我们最近的一项电子显微镜研究[Mater Sci Eng C 2009;29:2417-27]表明，在相转变诱导的纳米/超细晶（NG/UFG）基底上电结晶纳米羟基磷灰石（nHA）表现出脉状相互连接的纤维状结构，这种结构与骨的分级结构非常相似。NG/UFG 基底上的纤维状结构预计比平面更有利于细胞反应。相比之下，粗晶（CG）基底上的羟基磷灰石（HA）涂层更类似于薄膜而不是纤维状结构。受 HA 涂层结构差异的启发，我们在这里描述了前成骨细胞（MC3T3-E1）在生物活性 NG/UFG 和 CG 奥氏体不锈钢基底上的细胞-基底相互作用。NG/UFG 奥氏体不锈钢是通过冷变形奥氏体的新型控制相转变退火获得的。这个例子说明了细胞和分子生物学、材料科学和工程如何结合起来，增进我们对细胞-基底相互作用的理解。有趣的是，与 HA 涂层 CG 基底及其各自的未涂层（裸）基底相比，纳米羟基磷灰石（nHA）涂层 NG/UFG 基底的细胞反应表现出更好的细胞相容性、提高的初始细胞附着、更高的活力和增殖，以及更好的形态扩散，荧光和电子显微镜以及 MTT 分析均证实了这一点。从免疫荧光研究中也得出了类似的结论，该研究涉及检查与密集的肌动蛋白应力纤维和纤维连接蛋白相关的 vinculin 黏附斑接触的表达水平、SDS-PAGE 中的蛋白条带分析以及定量总蛋白分析。细胞反应的增强遵循以下顺序：nHA 涂层 NG/UFG>nHA 涂层 CG>NG/UFG>CG 基底。该研究的结果有望克服与具有显著改善细胞反应的特定物理和表面特性的纳米结构化表面工程相关的挑战。
