P-selectin
Upon platelet activation P-selectin, which is also known as CD62P, is rapidly mobilised from alpha granules to the platelet surface membrane, thereby allowing for the discrimination between non-activated and activated platelets. The expression of P-selectin also leads to leukocyte recruitment into the vessel via P-selectin glycoprotein ligand-1 (PSGL-1) (Furie and Furie, 2004). By conjugating microbubbles with either a P-selectin monoclonal antibody or a PSGL-1 recombinant targeting ligand, Davidson et al. visualised enhanced ultrasound imaging in the post-ischemic regions using a hind-limb ischemia murine model, as well as myocardial I/R injury in both a murine and a non-human primate model (Davidson et al., 2012, 2014). These microbubbles produced an increase in signal enhancement at the 90 min and 3 h time-points post-cardiac I/R injury (Figure 1) (Davidson et al., 2012). The area of contrast enhancement on ultrasound correlated with the area at risk of ischemia on histology.