Glycoprotein (GP) IIb/IIIa
GPIIb/IIIa receptor, also known as integrin
αIIbβ3 and CD41/CD61, is the most
abundant receptor on the membrane surface of platelets with 60,000 to
80,000 receptors per platelet. The expression of GPIIb/IIIa is
platelet-specific and upon platelet activation, the GPIIb/IIIa receptor
undergoes a conformational change from a low affinity to a high affinity
receptor for its natural ligand fibrinogen/fibrin. The
arginine-glycine-aspartic (RGD) peptide mimics the binding epitopes of
GPIIb/IIIa’s natural ligand fibrinogen, and has therefore been used for
the detection of vascular thrombosis via a range of imaging technologies
(Schumann et al., 2002; Klink et al., 2010; Zhou et al., 2011; Hu et
al., 2012; Unger et al., 2014; Guo et al., 2015; Kang et al., 2015; Rix
et al., 2016). Hu et al, demonstrated that microbubbles conjugated with
cyclic RGD peptides, facilitated the visualisation of thrombosis via
molecular ultrasound imaging (Figure 5) (Hu et al., 2012). In this
study, the authors demonstrated that brightness-mode ultrasound imaging
could be used to visualise the echogenic thrombi in the abdominal artery
of a rodent model. Colour Doppler imaging was also used to confirm the
vascular stenosis created by the thrombi (Hu et al., 2012).