Surface Modification with Lactadherin Augments the Attachment of Sonazoid Microbubbles to Glycoprotein IIb/IIIa

Arginine–glycine–aspartate (RGD)-carrying microbubbles (MBs) have been utilized as a specific contrast agent for glycoprotein IIb/IIIa (α _IIb β ₃ integrin)-expressing activated platelets in ultrasound molecular imaging. Recently, we found that surface modification with lactadherin provides the RGD motif on the surface of phosphatidylserine-containing clinically available MBs, Sonazoid. Here, we examined the potential of lactadherin-bearing Sonazoid MBs to be targeted MBs for glycoprotein IIb/IIIa using the custom-designed in vitro settings with recombinant α _IIb β ₃ integrin, activated platelets or erythrocyte-rich human clots. By modification of the surface with lactadherin, a large number of Sonazoid MBs were attached to the α _IIb β ₃ integrin-coated and platelet-immobilized plate. Additionally, the video intensity of clots after incubation with lactadherin-bearing Sonazoid MBs was significantly higher than that with unmodified Sonazoid MBs, implying the number of attached Sonazoid MBs was increased by the modification with lactadherin. Our results suggest that the lactadherin-bearing Sonazoid MBs have the potential to be thrombus-targeted MBs.