The inhibition of platelet adhesion and activation on collagen during balloon angioplasty by collagen-binding peptidoglycans

Prevention of Collagen-Induced Platelet Binding and Activation by Thermosensitive Nanoparticles

“…A collagen binding assay demonstrated the modified particles' ability to bind to a collagen I-coated surface. Particle binding increased with an increase in conjugated SILY, while LFA-modified particles showed a complete inability to bind to the collagen plate (46,61,62). Additionally, endocytic uptake of the loaded nanoparticles is expected to be minimal as they can be delivered directly to the damaged endothelium and allowed to bind to the collagenous layer that has been stripped of its native endothelial cells, allowing them to release their loaded peptide to the inflamed SMC.…”

“…Additionally, SILY peptides that are crosslinked via their terminal cysteine would have greater conformational freedom than those electrostatically associated with the particle surface. This would allow them to present the proper collagen-binding sites once suspended in an aqueous solution, and allow for competitive binding of the SILY to the exposed collagen while the nanoparticles would provide steric hindrance and prevent platelets from accessing any additional binding sites on the collagen (46,54). We found that while there is some electrostatic association between the particle and the SILY, a majority of the peptide is successfully covalently crosslinked to the particle using BMPH (Table II), resulting in a permanent stable attachment of the SILY peptide T h e r e t e n t i o n o f t h e i r a n i o n i c c h a rg e a nd thermosensitive properties allows the modified nanoparticles to load and release the therapeutic peptide KAFAK, with a final loading efficiency of 32%, and a burst release of over 70% of the final amount of KAFAK released occurring within the first 12 h. This is slightly lower than the loading efficiencies reported by other sulfated poly(NIPAM) nanoparticles (29,43) and can most likely be attributed partial charge neutralization by the attached SILY as well as the surface-bound SILY hindering diffusion of the KAFAK into the particle's core.…”

“…The blood was centrifuged for 20 min at 200×g and 25°C, and the top layer of platelet-rich plasma (PRP) was collected. The plates were rinsed three times with 1× PBS and 50 μL of PRP was added to each well and allowed to incubate at room temperature for 1 h. Following the incubation, 45 μL was removed from each well and mixed with 5 μL ETP (107 mM EDTA, 12 mM theophylline, and 2.8 mM prostaglandin E 1 ) to stop further platelet activation (46). The platelets were pelleted via centrifugation and the supernatant was diluted 1:10,000 in 1% BSA in 1× PBS and then run on a sandwich ELISA for platelet factor 4 (PF-4) and β-thromboglobulin (NAP-2) (R&D Systems) according to the manufacturer protocol.…”

“…DS-SILY has been shown to specifically bind to type I collagen, prevent platelet adhesion and activation, and promote endothelial migration on a collagencoated surface (46). The collagen-binding properties of DS-SILY are mainly attributed to the collagen I-binding peptide sequence, while the platelet binding inhibition is attributed to competition from the SILY peptide as well as to the dermatan sulfate backbone, which serves as a hydrophilic barrier to further prevent platelet attachment.…”

“…Our lab has previously developed a mimic of the proteoglycan decorin named DS-SILY, which consists of a collagen I-binding peptide attached to a dermatan sulfate backbone (45,46). DS-SILY has been shown to specifically bind to type I collagen, prevent platelet adhesion and activation, and promote endothelial migration on a collagencoated surface (46).…”