WEB Interaction of blood platelets with engineered fibrinogen scaffolds of different topographies
Biomaterial-blood interactions are critical for the successful tissue integration of implants and might be used to guide wound healing. Under physiological conditions, extracellular matrix (ECM) proteins instruct platelets to form a clot at wound sites, but the influence of ECM topography on platelet behaviour is not well understood.
In this project we investigated how platelets interact with fibrinogen scaffolds of different nanotopographies. Platelet-rich plasma (PRP) or washed platelets were incubated on three different substrates: physisorbed fibrinogen versus planar or nanofibrous fibrinogen scaffolds prepared by salt-induced self-assembly (Stapelfeldt et al., Biofabrication 2019; Stapelfeldt et al., Nanolett 2019). Samples were fixed and stained for confocal microscopy and image analysis to evaluate platelet activation in terms of adhesion morphology (F-actin organization), α-granule secretion (P-selectin surface expression), and procoagulant activity (phosphatidylserine exposure).
Platelets in PRP remained round on adsorbed or planar fibrinogen but spread and formed small clots on nanofiber scaffolds. In contrast, washed platelets adhered and spread on all substrates and developed similar adhesion morphologies. Most platelets on all substrates were P-selectin positive but showed an unsystematic variation in their phosphatidylserine exposure.
These preliminary results suggest that platelets interact more strongly with rougher fibrinogen surfaces. The underlying cellular and molecular mechanisms require further investigation. In future, these findings might be used to steer blood-biomaterial interactions by employing biomimetic nanotopographic designs.