The mediation of platelet quiescence by NO-releasing polymers via cGMP-induced serine 239 phosphorylation of vasodilator-stimulated phosphoprotein

Abstract

Nitric oxide (NO) releasing (NORel) materials have been shown to create localized increases in NO concentration by the release of NO from a diazeniumdiaolate-containing or S-nitrosothiol-containing polymer coating and the improvement of extracorporeal circulation (ECC) hemocompatibility. However, the mechanism and, in particular, the platelet upregulation of the NO/cGMP signaling protein, vasodilator-stimulated phosphoprotein phosphorylated at serine 239 (P-VASP (ser 239), for the improved ECC hemocompatibility via NO release still needs elucidation. In this work, two NORel polymeric coatings were evaluated in a 4 h rabbit thrombogenicity (RT) model and the anti-thrombotic mechanism investigated for rabbit platelet P-VASP upregulation. Polymer films containing 25 wt% diazeniumdiolated dibutylhexansdiamine (DBHD) or 5 wt% S-nitroso-N-acetylpenicillamine (SNAP) coated on the inner walls of ECC circuits yielded significantly reduced ECC thrombus formation and maintained normal platelet aggregation compared to polymer controls after 4 h of blood exposure. Platelet P-VASP (ser 239), a useful tool to monitor NO/cGMP signaling, was upregulated after 4 h on ECC and markedly increased after ex vivo sodium nitroprusside (SNP) stimulation. Interestingly, in the rabbit platelet, NO did not upregulate the cAMP P-VASP phosphoprotein P-VASP (ser 157) as previously shown in human platelets. These results suggest that NORel polymers preserve rabbit platelet quiescence by sustainng a level of cGMP signaling as monitored by P-VASP (ser 239) upregulation. The upregulation of this NO-mediated platelet signaling mechanism in this RT model indicates the potential for improved thromboresistance of any NORel-coated medical device.

RETRACTED ARTICLE: Small Diameter Blood Vessels Bioengineered From Human Adipose-derived Stem Cells

“…The nitric oxide production by the differentiated ECs is approximately 50% that of the hUVECs. Nitric oxide plays a potential role in thromboresistance by inhibiting platelet adhesion 29 30 . Compared with our previous study, the bioengineered vessels derived from the SMCs and ECs layers were analyzed histologically.…”

The effect of a polyurethane coating incorporating both a thrombin inhibitor and nitric oxide on hemocompatibility in extracorporeal circulation

“…It is well described that the synthesis and use of the NO donor, DBHD/N 2 O 2 , in ECLS circuits leads to improved hemocompatibility by the ultimate preservation of circulating platelets and maintenance of their normal function via the released NO (NORel) [3, 5, 17]. However, this NORel coating alone does not prevent the activation of the intrinsic coagulation pathway and the formation of fibrin clots which are present in the NORel circuits of the rabbit extracorporeal circulation (ECC) model.…”

“…Previous work from our laboratory and other investigators have established that NO releasing polymers (NORel) can prevent loss of circulating platelets and monocytes, prevent up to 75% of ECC thrombus formation and maintain preservation of platelet function to normal exogenous stimuli by inhibiting ECC-induced activation [1,5,26–32]. Together, these pieces of evidence provide a strong importance for NO in defining, in part, the hemocompatibility of biomaterials used in ECLS and confirms why normal vascular endothelium provides such a beneficial nonthrombogenic surface.…”

Development and hemocompatibility testing of nitric oxide releasing polymers using a rabbit model of thrombogenicity

“…Recent papers have described the details of the experimental setup for the 4-h studies for biomaterial hemocompatibility testing. 89, 111–113, 115, 116, 119, 126–128, 132 The key feature of the extracorporeal circuit (ECC) is the larger internal diameter tubing midway in the circuit loop. This larger tubing models the increased surface area and, more importantly, the increased turbulent blood flow that occurs in inline oxygenators and heat exchangers.…”