Development of novel submicron textured polyether(urethane urea) for decreasing platelet adhesion.

Ventricular assist devices have proven to be a useful clinical option for providing circulatory support as a bridge to transplantation and a mode of destination therapy. Thromboembolism is prevented by designing devices that use blood interfaces that either encourage biological material deposition and strong adhesion, or discourage deposition via surface chemistry, surface finish, and fluid flow fields. Minimum continuous or periodic wall shear forces and maximum time at reduced shear are important, and sometimes difficult-to-satisfy, design constraints. We present an approach to reducing platelet adhesion via surface topography, reducing surface area for platelet-material interaction. Large areas of polyether(urethane urea) were textured with two different sizes of ordered pillar arrays via two-stage replication molding without affecting surface chemistry. Pillars had subplatelet dimensions designed to reduce the surface area a platelet may contact. Platelet adhesion was assessed in a physiologically relevant shear stress range from 0-10 dyn/cm2 using a rotating disk and compared to smooth control. Adhesion was highest from 0-5 dyn/cm2. Surface texturing reduced platelet adhesion without increasing platelet activation in bulk suspension. This study demonstrates that material surface texture is an additional variable that may be used to reduce platelet adhesion under low shear stresses potentially reducing thromboembolism.