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Abstracts: ASAIO Bioengineering/tissue Engineering Abstracts

PLATELET ADHESION TO POLY(URETHANE UREA) IS REDUCED BY SUB-PLATELET SIZED SURFACE TOPOGRAPHIES

Milner, Keith R1; Balmer, Mallory1; Yamanaka, Hanako1; Snyder, Alan J1,2; Siedlecki, Christopher A1,2

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Platelet adhesion is a key component in thrombus formation on blood-contacting surfaces in medical devices. We present a method for reducing adhesion at low shear stress via surface texture. Pillars were fabricated on a biomedical polyether(urethane urea) (PUU) using a replication molding method. Master patterns were microfabricated on silicon wafers, consisting of ordered pillar arrays 700nm high. Two patterns were fabricated: 700nm pillar width and separation, or 400nm width and separation. Molds were cast using silicone elastomer. PUU replicas were prepared by casting PUU over the silicone negatives. Smooth PUU controls were prepared by casting on smooth silicone. The variation in platelet adhesion to PUU with shear stress was assessed using a rotating disk system, exposing bovine platelet-rich plasma to wall shear stress ranging from 0–67 dyn.cm-2 for 2 hr. Adherent platelets were immunofluorescently labeled and non-adherent platelet activation was assessed via flow cytometry. Microscopy revealed a higher incidence of platelet aggregates on smooth PUU, particularly at low shear. Total platelet adhesion reduced with increasing shear on both smooth and textured PUU and was equivalent for shear >4 dyn.cm-2. However adhesion was reduced on textured PUU at lower shear, significantly so for 700nm pillars. Flow cytometry revealed no significant difference in platelet activation after exposure to smooth or textured PUU. In summary, surface texture may act to reduce the adhesion of platelets to a biomedical PUU at low shear stress.

Copyright © 2005 by the American Society for Artificial Internal Organs