Background: Platelets have a strong tendency to be activated when they contact non-physiological and artificial surfaces. Minimization of surface-induced platelet activation is important for many biomedical applications such as in vivo-performance, platelet storage, and acceptance of an implant. However, inhibition of platelet-surface activation is challenging, and to date, controversies and open questions in this field still remain.

Aims: To minimize surface-induced platelet activation by i) modifying contact surface with bio-polymers, and ii) nanopatterning the underneath surface before seeding platelets.

Methods: Nanopatterns were fabricated using electron-beam lithography and FluidFM based atomic force microscopy (AFM). Characteristics of the surfaces were investigated using contact angle measurements while the stiffness of the gel was determined by AFM nanoindentation. Adhesion forces between single platelets and fabricated surfaces were determined by single-platelet force spectroscopy-based AFM. Platelet morphologies on surfaces were obtained by confocal laser microscopy and scanning electron microscopy (SEM). The geometry of nanogroove patterns was imaged with AFM and SEM. Platelet aggregometry was used to determine the effect of polymers on platelet aggregation.

Results: Both laminin and collagen-G gels formed on the glass surface reduced platelet activation. However, laminin showed a slower activation rate than collagen-G. The formation of stable and inert agarose hydrogel films and a mixture of agarose with nanoparticles effectively minimized surface-induced platelet activation even after a long time of storage. Nanopatterns together with laminin coating also strongly reduced platelet-surface adhesion and activation. Particularly, laminin-coated 100 nm groove patterns inhibited platelet activation better than the 500 nm size. The adhesion force between single platelets and these surfaces reduced strongly as compared with non-coated and non-patterned surfaces. The alteration of factors including adhesion force, topography, wettability, stiffness, swelling, and surface chemistry directly influence platelet morphology.

Conclusions: Surface-induced platelet activation can be minimized by seeding platelets on i) agarose hydrogel films, and ii) laminin-coated nanopatterns.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/new-strategies-for-minimization-of-surface-induced-platelet-activation/