Medizin & Gesundheit

Evaluation of Surface Micro-Structures for Endothelial Cell Retention under Supraphysiological Flow

One of the main challenges in medicine is the avoidance of blood coagulation due to the contact between blood and synthetic material within cardiovascular devices and even the prevention of rejection of cardiovascular implants. Thus, a full endothelialization of artificial surfaces represents the ideal solution.
The process of endothelialization includes the generation and maintenance of a confluent and stable endothelial monolayer under flow.

This work reports the effect of a new kind of substrate topography on endothelial cell density, connectivity and substrate coverage under high levels of flow induced wall shear stress. This new topography consisted of a honeycomb like hexagonal structure, dividing the substrate surface into 4.9 µm deep wells divided by 2 µm walls with a single side wall length of 20 µm. Human umbilical vein endothelial cells (HUVECs) were preconditioned at one hour of physiological shear of 1.4 Pa and subsequently exposed to high flowrates in a custom-made flow chamber to analyze the effect of supraphysiological wall shear stress levels (8 Pa and 10 Pa) on a confluent and functional endothelium. As a substrate a cyclic olefin copolymer (COC) foil, one half with a flat and the other half with hexagonal micro-structured surface, were used.

It could be shown that the surface topography led to an increase of cell density, connectivity and substrate coverage both before and after the experiment. Furthermore, the preconditioning routine of one hour physiological flow seemed to significantly increase the WSS threshold for cell detachment. In all, the combination of the hexagonal micro-structured surface with the preconditioning makes the endothelium more resistant to supraphysiological flow.

Adem Bayram
Lehr- / Forschungsinstitut
Eidgenössische Technische Hochschule Zürich (ETHZ)

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