Pharmacological characterization of nanoparticle-induced platelet microaggregation using quartz crystal microbalance with dissipation: comparison with light aggregometry

Abstract

Background

Engineered nanoparticles (NPs) can induce platelet activation and aggregation, but the mechanisms underlying these interactions are not well understood. This could be due in part to use of devices that study platelet function under quasi-static conditions with low sensitivity to measure platelet microaggregation. Therefore, in this study we investigated the pharmacological pathways and regulators of NP-induced platelet microaggregation under flow conditions at nanoscale using quartz crystal microbalance with dissipation (QCM-D) and compared the data thus obtained with those generated by light aggregometry.

Methods

Blood was collected from healthy volunteers, and platelet-rich plasma was obtained. Thrombin receptor-activating peptide, a potent stimulator of platelet function, and pharmacological inhibitors were used to modulate platelet microaggregation in the presence/absence of silica (10 nm and 50 nm) and polystyrene (23 nm) NPs. Light aggregometry was used to study platelet aggregation in macroscale. Optical, immunofluorescence, and scanning electron microscopy were also used to visualize platelet aggregates.

Results

Platelet microaggregation was enhanced by thrombin receptor-activating peptide, whereas prostacyclin, nitric oxide donors, acetylsalicylic acid, and phenanthroline, but not adenosine diphosphate (ADP) blockers, were able to inhibit platelet microaggregation. NPs caused platelet microaggregation, an effect not detectable by light aggregometry. NP-induced microaggregation was attenuated by platelet inhibitors.

Conclusion

NP-induced platelet microaggregation appears to involve classical proaggregatory pathways (thromboxane A₂-mediated and matrix metalloproteinase-2-mediated) and can be regulated by endogenous (prostacyclin) and pharmacological (acetylsalicylic acid, phenanthroline, and nitric oxide donors) inhibitors of platelet function. Quartz crystal microbalance with dissipation, but not light aggregometry, is an appropriate method for studying NP-induced microaggregation.

Keywords:

• platelet microaggregation
• quartz crystal microbalance with dissipation
• pharmacology
• nanoparticles

Acknowledgments

The work was supported by a Science Foundation Ireland (SFI) principal investigator grant to MWR (S.F.I.O5/FE1/B862) and SFI-RFP grant (RFP/BMT2781) to CM. CM is an SFI Stokes lecturer. MJSM is an Ussher lecturer in Nanopharmaceutical Drug Discovery at Trinity College Dublin. KAT received funding from the Jagiellonian University Medical College statutory funds for young scientists. The authors would like to acknowledge Heath Bagshaw and Neal Leddy (Centre for Microscopy and Analysis) for their assistance with the scanning electron microscopy and Esther Rufino for technical assistance.

Disclosure

The authors report no conflicts of interest in this work.