A Computational Fluid Dynamics (CFD) analysis to optimize size and shape pattern for endothelial cell growth

Abstract

Blood-contacting devices are vital in treating cardiovascular diseases but may trigger coagulation and thrombosis, requiring lifelong anticoagulation or repeated surgeries. Endothelial cells, which regulate vascular homeostasis, form a barrier between blood and tissue. Promoting stable endothelialization on device surfaces may reduce these risks. However, conventional devices often fail due to high wall shear stress (WSS), which damages the endothelium. This study numerically evaluates surface topographies to identify those that lower WSS and enhance cell stability.

CFD simulations were used to estimate WSS on quadrangular and grooved patterns (10 × 4 mm) with depths of 1, 5, 12 mm, spaced 20 mm apart. Two flow conditions were considered: steady (0.4 m/s) and pulsatile with a sinusoidal profile. Blood was modeled as a Newtonian fluid (density: 1060 kg/m³, viscosity: 3.5·10⁻³ Pa·s).

In-silico simulations assessed the impact of meso- and micro-topographies on WSS across various patterns. After an initial instability, WSS stabilized along the 10 mm section. The highest mean WSS (12 Pa) occurred at the shallowest depth, decreasing to 8 Pa and 2 Pa with greater depths. Notably, 8 Pa and 2 Pa fall within the physiological range favorable to cell survival. The comparison with grooved topographies, showed similar WSS at 1 and 5 mm depths, increasing to 5 Pa at 12 mm.

Surface topography affects WSS and thereby endothelial growth. The square pattern best preserves tissue integrity by reducing WSS. Future work will explore additional patterns and flow conditions. Cellular experiments are planned to validate the numerical models.