Adverse events triggered by the direct contact between blood and synthetic materials constitute a sincere shortcoming of cardiovascular implant technology. A well-connected autologous endothelium, generated through the process of endothelialization, impedes such interaction and endows the implant luminal interface with optimal protection. The endothelialization of artificial substrates is the result of a complex interplay between endothelial cells (ECs), surface topography, and flow-generated wall shear stress (WSS). This is however tainted by the pro-inflammatory signaling, typical of cardiovascular patients, which compromises endothelial integrity and survival. Here, we challenge human endothelial monolayers with the pro-inflammatory factor TNF-α under realistic WSS conditions. In these experimental settings we demonstrate that the simple contact between ECs and an optimized surface geometry can inhibit NF-kB activation downstream of TNF-α yielding increased stability of VE-Cadherin mediated cell-to-cell junctions and of focal adhesions. Therefore the here-presented topographic modification can be implemented on a range of artificial substrates enabling their endothelialization under supra-physiological flow and in the presence of pro-inflammatory insults. These new findings constitute an important step toward achieving the full hemocompatibility of cardiovascular implants.

Endothelialization strategies aim at protecting the surface of cardiovascular devices upon their interaction with blood by the generation and maintenance of a mature monolayer of endothelial cells. Rational engineering of the surface micro-topography at the luminal interface provides a powerful access point to support the survival of a living endothelium under the challenging hemodynamic conditions created by the implant deployment and function. Surface structuring protocols must however be adapted to the complex, non-planar architecture of the target device precluding the use of standard lithographic approaches. Here, a novel patterning method, harnessing the condensation and evaporation of water droplets on a curing liquid elastomer, is developed to introduce arrays of microscale wells on the surface of a biocompatible silicon layer. The resulting topographies support the in vitro generation of mature human endothelia and their maintenance under dynamic changes of flow direction or magnitude, greatly outperforming identical, but flat substrates. The structuring approach is additionally demonstrated on non-planar interfaces yielding comparable topographies. The intrinsically free-form patterning is therefore compatible with a complete and stable endothelialization of complex luminal interfaces in cardiovascular implants.