Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland.
Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland; Clinic of Cardiac and Vascular Surgery, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
Biomaterials. 2014 Oct;35(30):8479-86. doi: 10.1016/j.biomaterials.2014.06.046. Epub 2014 Jul 10.
Interaction between platelets and artificial materials within cardiovascular devices triggers blood coagulation and represents a frequent adverse response to implant deployment. Avoidance of this interaction is obtained through the generation and sustenance under flow of a confluent and stable endothelial monolayer covering the luminal device surface, altogether defined as the process of endothelialization. Supraphysiological wall shear stress (WSS) levels generated within vascular assist devices (VADs) constitute a major challenge toward endothelialization. Here we report the experimental demonstration that stable endothelialization can be achieved at supraphysiological WSS levels by pure means of appropriate surface micro-structuring. Using a custom-designed flow bioreactor we exposed endothelial monolayers to physiological and supraphysiological WSS levels and investigated the resulting integrity of cell-to-cell junctions, the cell density and the cell polarization. At physiological WSS levels, optimal endothelialization was obtained independently from surface topography. However, at higher WSS levels, only monolayers grown on appropriately micro-structured surfaces preserved optimal integrity. Under these flow conditions, endothelial cells polarized by the contact with the micro-structure and, interestingly, oriented themselves in the direction perpendicular to flow. Such endothelial layers withstood WSS levels exceeding of 100% or more the thresholds detected on flat substrates.
在心血管设备中，血小板与人工材料之间的相互作用会引发血液凝固，这是对植入物植入的一种常见不良反应。通过在覆盖设备内腔表面的连续且稳定的内皮单层的形成和维持下产生的超生理壁切应力（WSS）水平会对内皮化构成重大挑战。在这里，我们通过适当的表面微结构的纯方法证明了在超生理 WSS 水平下可以实现稳定的内皮化。我们使用定制的流动生物反应器使内皮单层暴露于生理和超生理 WSS 水平，并研究了由此产生的细胞-细胞连接的完整性、细胞密度和细胞极化。在生理 WSS 水平下，最佳的内皮化独立于表面形貌获得。然而，在更高的 WSS 水平下，只有在适当的微结构化表面上生长的单层才能保持最佳的完整性。在这些流动条件下，与微结构接触的内皮细胞发生极化，并且有趣的是，它们自身定向于垂直于流动的方向。这种内皮层能够承受超过在平面基底上检测到的阈值 100%或更多的 WSS 水平。
