Intimatan (dermatan 4,6-O-disulfate) prevents rethrombosis after successful thrombolysis in the canine model of deep vessel wall injury

2022 Update of the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) Domain 6: Defining rational use of thrombolytics

OBJECTIVES

To systematically review available evidence and establish guidelines related to the use of thrombolytics for the management of small animals with suspected or confirmed thrombosis.

DESIGN

PICO (Population, Intervention, Control, and Outcome) questions were formulated, and worksheets completed as part of a standardized and systematic literature evaluation. The population of interest included dogs and cats (considered separately) and arterial and venous thrombosis. The interventions assessed were the use of thrombolytics, compared to no thrombolytics, with or without anticoagulants or antiplatelet agents. Specific protocols for recombinant tissue plasminogen activator were also evaluated. Outcomes assessed included efficacy and safety. Relevant articles were categorized according to level of evidence, quality, and as to whether they supported, were neutral to, or opposed the PICO questions. Conclusions from the PICO worksheets were used to draft guidelines, which were subsequently refined via Delphi surveys undertaken by the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) working group.

RESULTS

Fourteen PICO questions were developed, generating 14 guidelines. The majority of the literature addressing the PICO questions in dogs is experimental studies (level of evidence 3), thus providing insufficient evidence to determine if thrombolysis improves patient-centered outcomes. In cats, literature was more limited and often neutral to the PICO questions, precluding strong evidence-based recommendations for thrombolytic use. Rather, for both species, suggestions are made regarding considerations for when thrombolytic drugs may be considered, the combination of thrombolytics with anticoagulant or antiplatelet drugs, and the choice of thrombolytic agent.

CONCLUSIONS

Substantial additional research is needed to address the role of thrombolytics for the treatment of arterial and venous thrombosis in dogs and cats. Clinical trials with patient-centered outcomes will be most valuable for addressing knowledge gaps in the field.

Galactosaminoglycans: Medical Applications and Drawbacks

Galactosaminoglycans (GalAGs) are sulfated glycans composed of alternating N-acetylgalactosamine and uronic acid units. Uronic acid epimerization, sulfation patterns and fucosylation are modifications observed on these molecules. GalAGs have been extensively studied and exploited because of their multiple biomedical functions. Chondroitin sulfates (CSs), the main representative family of GalAGs, have been used in alternative therapy of joint pain/inflammation and osteoarthritis. The relatively novel fucosylated chondroitin sulfate (FCS), commonly found in sea cucumbers, has been screened in multiple systems in addition to its widely studied anticoagulant action. Biomedical properties of GalAGs are directly dependent on the sugar composition, presence or lack of fucose branches, as well as sulfation patterns. Although research interest in GalAGs has increased considerably over the three last decades, perhaps motivated by the parallel progress of glycomics, serious questions concerning the effectiveness and potential side effects of GalAGs have recently been raised. Doubts have centered particularly on the beneficial functions of CS-based therapeutic supplements and the potential harmful effects of FCS as similarly observed for oversulfated chondroitin sulfate, as a contaminant of heparin. Unexpected components were also detected in CS-based pharmaceutical preparations. This review therefore aims to offer a discussion on (1) the current and potential therapeutic applications of GalAGs, including those of unique features extracted from marine sources, and (2) the potential drawbacks of this class of molecules when applied to medicine.

Molecular engineering of glycosaminoglycan chemistry for biomolecule delivery

Glycosaminoglycans (GAGs) are linear, negatively charged polysaccharides that interact with a variety of positively charged growth factors. In this review article the effects of engineering GAG chemistry for molecular delivery applications in regenerative medicine are presented. Three major areas of focus at the structure-function-property interface are discussed: (1) macromolecular properties of GAGs; (2) effects of chemical modifications on protein binding; (3) degradation mechanisms of GAGs. GAG-protein interactions can be based on: (1) GAG sulfation pattern; (2) GAG carbohydrate conformation; (3) GAG polyelectrolyte behavior. Chemical modifications of GAGs, which are commonly performed to engineer molecular delivery systems, affect protein binding and are highly dependent on the site of modification on the GAG molecules. The rate and mode of degradation can determine the release of molecules as well as the length of GAG fragments to which the cargo is electrostatically coupled and eventually released from the delivery system. Overall, GAG-based polymers are a versatile biomaterial platform offering novel means to engineer molecular delivery systems with a high degree of control in order to better treat a range of degenerated or injured tissues.

Disodium disuccinate astaxanthin prevents carotid artery rethrombosis and ex vivo platelet activation

BACKGROUND/AIMS

The disodium disuccinate derivative of astaxanthin (DDA) is a carotenoid antioxidant under development for the treatment of ischemic cardiovascular events. Recent evidence suggests that reactive oxygen species (ROS) play an important role in platelet activation. This study seeks to investigate the effects of a reactive oxygen species quencher, DDA, in a canine model of carotid artery thrombosis.

METHODS

After formation of an occlusive carotid thrombus, dogs were administered recombinant tissue plasminogen activator intra-arterially to achieve thrombolysis in the presence of either 0.9% NaCl solution or DDA (10-50 mg/kg i.v. infusion). Ex vivo platelet aggregation and tongue bleeding times were measured before and after drug administration. Residual thrombus mass was analyzed at the end of each experiment.

RESULTS

The data indicated a dose- dependent reduction in the incidence of carotid artery rethrombosis. In addition, platelet aggregation and thrombus weights were dose-dependently inhibited by DDA. No change was recorded in tongue bleeding time among the treatment groups.

CONCLUSIONS

The data demonstrate that at the doses used in this study, DDA significantly reduced the incidence of secondary thrombosis while maintaining normal hemostasis. The results suggest that upon further study, DDA may one day find utility in revascularization procedures.

Effect of oversulfated dermatan sulfate derivatives on platelet aggregation

We have investigated the effect on human platelet aggregation of native dermatan sulfate (DS) and three oversulfated DS derivatives with different sulfur contents, and compared it with that of unfractionated heparin. An inhibitory effect on collagen-induced platelet aggregation was observed only with unfractionated heparin at high concentrations, whereas no inhibitory effect was observed when arachidonic acid was used. Heparin was the most potent inhibitor of the thrombin-induced platelet aggregation in platelet-rich plasma (PRP), whereas the oversulfated DS had a higher potency than the native DS. All these glycosaminoglycans (GAGs) also inhibited thrombin-induced aggregation of washed platelets in the presence of antithrombin (AT) or heparin cofactor II (HCII) but not in their absence. Heparin was by far the most potent inhibitor of washed platelet aggregation in the presence of AT, whereas the inhibitory effects of the DS (native or oversulfated) were lower but dependent on the sulfur content. In the presence of HCII, DSb, a slightly oversulfated DS, had the highest inhibitory effect, whereas heparin and DSd, the most oversulfated derivative, had lower potencies in this case. These data suggest that the inhibition of thrombin-induced platelet aggregation by the oversulfated DS derivatives is related to their ability to potentiate thrombin inactivation by AT or HCII. Hence, the oversulfated DS derivatives may not have an effect per se on the inhibition of platelet aggregation. They may constitute a new class of anticoagulants with enhanced anticoagulant effects in comparison with the native DS, but with only minor side-effects of bleeding in comparison with heparin.

The relationship between the structure of dermatan sulfate derivatives and their antithrombotic activities

To study the relationship between the structure of dermatan sulfate (DS) derivatives and their anti-thrombotic activities, DS-derived oligosaccharides (with different structures and relative molecular weight (M(r))) were prepared, and the effects of the DS-derived oligosaccharides on the activities of heparin cofactor II (HCII), activated protein C (APC), blood platelet, and vascular endothelial cells were studied. The major disaccharides of DS and polysulfated dermatan sulfate (PSDS) were IdoA-1-->3-GalNAc-4-OSO(3) and IdoA-2OSO(3)-1-->3-GalNAc4, 6-diOSO(3), respectively. The results showed that the consequence of the thrombotic inhibitory effects of DS and its derivatives were as follows: PSDS>low molecular weight polysulfated dermatan sulfate (LPSDS)>DS. Both DS and PSDS inhibited platelet aggregation in the concentration-dependent manner, and the IC(50) value of DS and PSDS is 12.7+/-1.3 and 28.6+/-0.9 mg/mL, respectively. DS oligosaccharides (DSOSs) and PSDS oligosaccharides (PSDSOSs) both significantly inhibited P-selectin expression on platelet surface (P<0.01), while DSOSs have no different effect compared with PSDSOSs. DSOSs and PSDSOSs significantly enhanced the activity of HCII in inhibiting thrombin in the plasma. The most active PSDSOS was PSDSOS(1) with M(r) of 4959, which enhanced the HCII activity by 91% (P<0.01). The experiments on APC activity showed that DS and its derivatives enhanced APC activity. The most active PSDSOS was PSDSOS(3) with M(r) of 2749, which enhanced the APC activity to 331+/-27% (P<0.01). DSOSs and PSDSOSs enhanced tissue plasminogen activator (t-PA) activity and reduced the plasminogen activator inhibitor (PAI) activity from cultured human umbilical vein endothelial cells (HUVEC), resulting in the ratio of t-PA/PAI going up. PSDSOSs which have the same M(r) as DSOSs produced more active effects in above assays, except for platelet aggregation.