Delineating the roles of the GPIIb/IIIa and GP-Ib-IX-V platelet receptors in mediating platelet adhesion to adsorbed fibrinogen and albumin

Citation

Sivaraman, Balakrishnan & Latour, Robert A. (2011). Delineating the roles of the GPIIb/IIIa and GP-Ib-IX-V platelet receptors in mediating platelet adhesion to adsorbed fibrinogen and albumin. Biomaterials, 32(23), 5365-5370.

Abstract

Platelet adhesion to adsorbed plasma proteins, such as fibrinogen (Fg), has been conventionally thought to be mediated by the GPIIb/IIIa receptor binding to Arg-Gly-Asp (RGD)-like motifs in the adsorbed protein. In previous studies, we showed that platelet adhesion response to adsorbed Fg and Alb was strongly influenced by the degree of adsorption-induced protein unfolding and that platelet adhesion was only partially blocked by soluble RGD, with RGD-blocked platelets adhering without activation. Based on these results, we hypothesized that in addition to the RGD-specific GPIIb/IIIa receptor, which mediates both adhesion and activation, a non-RGD-specific receptor set likely also plays a role in platelet adhesion (but not activation) to both Fg and albumin (Alb). To identify and elucidate the role of these receptors, in addition to GPIIb/IIIa, we also examined the GPIb-IX-V receptor complex, which has been shown to mediate platelet adhesion (but not activation) in studies by other groups. The platelet suspension was pretreated with either a GPIIb/IIIa-antagonist drug Aggrastat(®) or monoclonal antibodies 6B4 or 24G10 against GPIb-IX-V prior to adhesion on Fg- and Alb-coated OH- and CH(3)-functionalized alkanethiol self-assembled monolayer surfaces. The results revealed that GPIIb/IIIa is the primary receptor set involved in platelet adhesion to adsorbed Fg and Alb irrespective of their degree of adsorption-induced unfolding, while the GPIb-IX-V receptor complex plays an insignificant role. Overall, these studies provide novel insights into the molecular-level mechanisms mediating platelet interactions with adsorbed plasma proteins, thereby assisting the biomaterials field develop potent strategies for inhibiting platelet-protein interactions in the design of more hemocompatible cardiovascular biomaterials and effective anti-thrombotic therapies.

Keyword(s)

Adsorption
Antibodies, Monoclonal
Circular Dichroism
Fatty Alcohols
Fibrinogen
gold
Humans
Platelet Adhesiveness
Platelet Glycoprotein GPIb-IX Complex
Platelet Glycoprotein GPIIb-IIIa Complex
Platelet Membrane Glycoproteins
Protein Conformation
Protein Structure, Secondary
Serum Albumin
Silicones
Sulfhydryl Compounds
Tyrosine

Reference Type

Journal Article

Secondary Title

Biomaterials

Author(s)

Sivaraman, Balakrishnan
Latour, Robert A.

Year Published

2011

Volume Number

32

Issue Number

23

Pages

5365-5370

ISSN/ISBN

1878-5905

DOI

10.1016/j.biomaterials.2011.04.011