Exploring the Role of Stent Strut Geometry in Cellular Behavior: An In Vitro Chip Model to Understand In-Stent Restenosis

Stent-based balloon angioplasty is commonly used to treat occluded arteries, but patients still suffer from in-stent restenosis (ISR), a recurrent lumen narrowing. Stent design plays a crucial role in ISR, yet current clinical research cannot isolate the effects of geometry alone. To tackle this problem and allow studying the underlying mechanobiological mechanisms, an in vitro platform containing geometries closely mimicking representative stent strut cross-sectional designs are designed and fabricated. This paper presents the fabrication and a biological validation of the in vitro platform. Morphological analysis revealed that strut-like geometries alter cellular morphology. This analysis further revealed that sharp cornered geometries (rectangle, triangle, trapezium) induced cell proliferation and extracellular matrix isotropy compared to smooth, rounded geometries (circle, oval, hexagon). Rho/ROCK-inhibition suggests intracellular tension as essential force for these responses. The outcomes are in line with clinical trials, where sharp strut shapes show increased neointimal tissue formation. The platform holds great potential for the development of improved stent designs with reduced ISR risk.