The Influence of Micropatterned Surfaces on Platelet Adhesion to Reduce the Risk of Thrombus Formation in Left...

Surface micropatterning is being explored as a strategy to mitigate thrombus formation and reduce long-term anticoagulation requirements in left ventricular assist devices (LVADs). This study investigated whether specific micro-topographies can modulate platelet deposition under LVAD supraphysiological wall shear stress (WSS) conditions.

A custom microfluidic platform was developed to generate a linear WSS gradient from 16 to 130 Pa. Microchannels were patterned with reverse cones and hemispheres in small (1-3 µm) and large (3-9 µm) sizes using two-photon polymerization and nanoimprinting. Human blood was perfused through the microchannels, and platelet deposition was quantified over time as the area coverage ratio (Aₚₗₜ/Aₜₒₜ) and area under the curve (AUC). Platelet detachment events were counted as an indicator of thrombus stability, and computational simulations supported the interpretation of local shear conditions.

Consistent trends emerged, although no statistical differences were observed relative to flat controls. Aₚₗₜ/Aₜₒₜ increased with WSS for all surfaces. At 16 Pa, small and large cones reduced platelet adhesion by approximately 84 and 98%, respectively, compared to flat controls. At 49 Pa, the reduction was about 95% for small cones and 80% for large cones. Conical geometries also promoted platelet washout at higher WSS. Small hemispherical features showed more than 50% lower platelet adhesion than flat surfaces for WSS > 16 Pa, with limited thrombus growth.

Conical micropatterns may be most effective at limiting platelet adhesion at lower WSS, while small hemispheres may perform better at higher WSS. These trends suggest a surface-shear interaction that warrants further investigation for LVAD surface optimization.