Ultrafast Laser Processing of Nanostructured Patterns for the Control of Cell Adhesion and Migration on Titanium Alloy

Femtosecond laser texturing is a promising surface functionalization technology to improve the integration and durability of dental and orthopedic implants. Four different surface topographies were obtained on titanium-6aluminum-4vanadium plates by varying laser processing parameters and strategies: surfaces presenting nanostructures such as laser-induced periodic surface structures (LIPSS) and 'spikes', associated or not with more complex multiscale geometries combining micro-pits, nanostructures and stretches of polished areas. After sterilization by heat treatment, LIPSS and spikes were characterized to be highly hydrophobic, whereas the original polished surfaces remained hydrophilic. Human mesenchymal stem cells (hMSCs) grown on simple nanostructured surfaces were found to spread less with an increased motility (velocity, acceleration, tortuosity), while on the complex surfaces, hMSCs decreased their migration when approaching the micro-pits and preferentially positioned their nucleus inside them. Moreover, focal adhesions of hMSCs were notably located on polished zones rather than on neighboring nanostructured areas where the protein adsorption was lower. All these observations indicated that hMSCs were spatially controlled and mechanically strained by the laser-induced topographies. The nanoscale structures influence surface wettability and protein adsorption and thus influence focal adhesions formation and finally induce shape-based mechanical constraints on cells, known to promote osteogenic differentiation. La texturation au laser femtoseconde est une technologie de fonctionnalisation de surface prometteuse pour améliorer l'intégration et la durabilité des implants dentaires et orthopédiques. Quatre topographies de surface différentes ont été obtenues sur des plaques de titane-6aluminium-4vanadium en faisant varier les paramètres et stratégies de traitement laser: des surfaces présentant des nanostructures telles que des structures de surface périodiques induites par laser (LIPSS) et des `` pointes '', associées ou non à des géométries multi-échelles plus complexes combinant des micro - des fosses, des nanostructures et des étendues de zones polies. Après stérilisation par traitement thermique, les LIPSS et les pointes ont été caractérisés comme étant hautement hydrophobes, tandis que les surfaces polies d'origine restaient hydrophiles. Les cellules souches mésenchymateuses humaines (hMSC) cultivées sur de simples surfaces nanostructurées se sont