题 目：3D Micro- and Nano-hemispherical Surface Imprints Modulate
时 间：2019年11月22日（星期五）15:00
地 点：四号学院楼3083室
主持人：何创龙 教授
欢迎各位老师和同学参加！
报告人简介：
杨伟国，任香港大学医学院矫形及创伤外科副教授（终身聘任），香港大学深圳医院深圳骨科创伤修复新技术重点实验室副主任，香港大学立之学院副经理。1998年本科毕业于香港城市大学，主修材料科学。随后进入香港大学医学院攻读骨科硕士及博士学位。毕业后，在矫形及创伤外科学系从事有关矫正脊柱畸形病症的研究工作。杨教授在香港大学医学院和香港大学深圳医院均有实验室研究基地，团队成员来自材料、医学、生物学和化学等专业，研究领域包括脊柱畸形及骨创伤、生物医用材料、镁合金骨科临床应用、骨科内植入器械开发等。发表了230多篇SCI论文，引用次数超过7500次，H-index为49。在Clarivate Analytics的ESI排行榜上，杨教授从2014开始连续6年入选生物材料领域Top1％科学家，共获得6800多万港币经费资助。此外, 他还获取30多项美国或其他国家发明专利，并获得香港科学会青年科学家奖、香港工程师学会青年工程师优异奖、第十三届COA学术大会的骨科基础青年研究二等奖和2019年度香港大学医学院最佳论文奖等奖项。杨教授还创立了OrthoSmart有限公司，兼任公司首席执行官，致力于骨修复材料的临床转化。
报告内容简介：
Osseointegration and inflammatory response at the bone-implant interface is of paramount importance for the success of orthopaedic implantations and their durability in long-term. Among a number of studies focused on modifying biomaterial physical and chemical properties, the design of surface topography still plays a significant role due to the ease of fabrication and clinical translation. Herein, a series of TiO2 hemisphere patterns ranging from nanoscale to microscale were prepared providing a platform on a 3D structure to study the cellular responses of mouse embryo osteoblast precursor cells (MC3T3-E1) and RAW264.7 macrophages in the absence of other surface features and additional osteogenic supplements in culture medium. This study aims to investigate the underlying correlations between surface topography and cellular behaviors of bone cells. Four groups of TiO2 hemispheres labeled as NWs-90, NWs-500, MWs-1, and MWs-5 with different diameters (i.e. 90 nm, 500 nm, 1 μm, and 5 μm) were prepared for further experiments. The surface properties including topography and materials structure were characterized by SEM, AFM and XRD, while the osteogenic differentiation capability and inflammatory responses of these patterns was validated by mouse pre-osteoblasts and RAW264.7 macrophages, respectively. The results revealed that the cell on flat Ti surface exhibited typical spindle like shapes with smooth boundaries, while the cells on various TiO2 hemisphere patterns presented with various morphologies. The NWs-90 surface was able to upregulate the ALP activity and mineralization, while the Runx2 and OCN genes were up-regulated by NWs-500 surface. Interestingly, NWs-90 sample convinced macrophages towards to M2 polarization with the highest expression level of anti-inflammatory markers (IL-4 and IL-10) and the lowest level of pro-inflammatory markers (TNF-α and IL-1β) among other samples. We believe that different intervals between TiO2 hemisphere patterns generated various mechanical resistances to cells and their filament structures were under stretching. Hence, this stress led to cytoskeleton rearrangement and then modulated cell morphologies, signal transduction indirectly and gene expression directly.
