A Simple Method to Measure Dermatan Sulfate at Sub-Microgram Concentrations in Plasma

Anti-Coagulant and Anti-Thrombotic Properties of Blacklip Abalone (Haliotis rubra): In Vitro and Animal Studies

Sulphated polysaccharides with anti-thrombotic and anti-coagulant activities have been found in various marine biota. In this study, a previously characterised anti-thrombotic and anti-coagulant extract from blacklip abalone was fractionated by anion exchange chromatography (AEC), pooled (on a sulphated polysaccharide basis) and administered to Wistar rats via oral gavage (N = 8) for assessment as an oral therapeutic. To ensure that the preparation had anti-coagulant activity prior to oral administration, it was assessed in rat blood by thromboelastography (TEG) significantly increasing reaction (R) time (or time until clot formation). Following in vitro confirmation of anti-coagulant activity, 40 mg of the preparation was orally administered to rats with blood samples collected at 2, 4, and 6 h post-gavage. Assessment of all blood samples by TEG showed some prolongation of R time from 355 to 380 s after 4 h. Dosing of the post-gavage blood samples with the abalone preparation to confirm anti-thrombotic activity in vitro revealed residual anti-coagulant activity, further suggesting that oral administration did increase anti-coagulant potential in the collected blood but that bioavailability was low. Assessment of tissues and haematological parameters showed no obvious harmful effects of the abalone preparation in animals. In summary, even though oral administration of fractionated and pooled blacklip abalone extract to rats delayed clotting after 4 h, bioavailability of the preparation appeared to be low and may be more appropriate for intravenous administration as an anti-thrombotic or anti-coagulant therapeutic.

In vitro anti-thrombotic and anti-coagulant properties of blacklip abalone (Haliotis rubra) viscera hydrolysate

Abalone viscera contain sulphated polysaccharides with anti-thrombotic and anti-coagulant activities. In this study, a hydrolysate was prepared from blacklip abalone (Haliotis rubra) viscera using papain and bromelain and fractionated using ion exchange and size exclusion chromatography. Hydrolysates and fractions were investigated for in vitro thrombin inhibition mediated through heparin cofactor II (HCII) as well as anti-coagulant activity in plasma and whole blood. On the basis of sulphated polysaccharide concentration, the hydrolysate inhibited thrombin through HCII with an inhibitor concentration at 50% (IC50) of 16.5 μg/mL compared with 2.1 μg/mL for standard heparin. Fractionation concentrated HCII-mediated thrombin inhibition down to an IC50 of 1.8 μg/mL and improved anti-coagulant activities by significantly delaying clotting time. This study confirmed the presence of anti-thrombotic and anti-coagulant molecules in blacklip abalone viscera and demonstrated that these activities can be enriched with a simple chromatography regime. Blacklip abalone viscera warrant further investigation as a source of nutraceutical or functional food ingredients. Graphical abstract Schematic showing preparation of bioactive extracts and fractions from blacklip abalone.

In vitro Anti-Thrombotic Activity of Extracts from Blacklip Abalone (Haliotis rubra) Processing Waste

Waste generated from the processing of marine organisms for food represents an underutilized resource that has the potential to provide bioactive molecules with pharmaceutical applications. Some of these molecules have known anti-thrombotic and anti-coagulant activities and are being investigated as alternatives to common anti-thrombotic drugs, like heparin and warfarin that have serious side effects. In the current study, extracts prepared from blacklip abalone (Haliotis rubra) processing waste, using food grade enzymes papain and bromelain, were found to contain sulphated polysaccharide with anti-thrombotic activity. Extracts were found to be enriched with sulphated polysaccharides and assessed for anti-thrombotic activity in vitro through heparin cofactor-II (HCII)-mediated inhibition of thrombin. More than 60% thrombin inhibition was observed in response to 100 μg/mL sulphated polysaccharides. Anti-thrombotic potential was further assessed as anti-coagulant activity in plasma and blood, using prothrombin time (PT), activated partial thromboplastin time (aPTT), and thromboelastography (TEG). All abalone extracts had significant activity compared with saline control. Anion exchange chromatography was used to separate extracts into fractions with enhanced anti-thrombotic activity, improving HCII-mediated thrombin inhibition, PT and aPTT almost 2-fold. Overall this study identifies an alternative source of anti-thrombotic molecules that can be easily processed offering alternatives to current anti-thrombotic agents like heparin.

Pharmacokinetics and pharmacodynamics of intramuscular dermatan sulfate revisited : a single- and repeated-dose study in healthy volunteers

OBJECTIVE

To assess the pharmacokinetics and effects on blood coagulation of dermatan sulfate (DS), a glycosaminoglycan with antithrombotic properties, following intravenous and single and repeated intramuscular administrations. The mean molecular weight of DS is currently 22kD, i.e. 5kD lower than batches used in the early development of the compound.

SUBJECTS AND METHODS

Each of 14 male healthy volunteers received DS 300mg as an 8-hour intravenous infusion and as single and repeated (once daily for 9 days) intramuscular injections. Nine of the same subjects were also given DS 100mg and 200mg as single intramuscular doses. Plasma DS concentrations were measured with a specific chromogenic assay. Activated partial thromboplastin time (aPTT) and thrombin clotting time (TCT) responses were also determined.

RESULTS

The mean +/- SD volume of distribution and terminal half-life of DS were 6.0 +/- 1.4L and 0.9 +/- 0.2h after intravenous infusion. Maximum plasma concentration (C(max)) and area under the plasma concentration-time curve after single intramuscular injections were dose-proportional. After repeated intramuscular administration, steady state was reached by day 3. On day 9, plasma DS fluctuated between 4.3 +/- 1.5 (C(max)) and 0.9 +/- 0.4 (minimum plasma concentration at steady state) mg/L, time to C(max) was 3.4 +/- 0.8h, terminal half-life was 12.2 +/- 4.1h and the accumulation factor was 2.0 +/- 0.5. Geometric mean bioavailability of intramuscular DS was 54% and 79% after single and repeated 300mg administration, respectively. aPTT and TCT responses were both linearly related to plasma DS concentrations, with TCT showing greater responsivity.

CONCLUSION

As compared with earlier DS studies, the present data showed a greater extent of DS absorption after single intramuscular administration and a faster absorption rate after repeated dosing, and provided evidence of dose-response predictability. These findings may explain the improved antithrombotic efficacy of DS observed in a recent clinical trial.

Antithrombin activity and disaccharide composition of dermatan sulfate from different bovine tissues

Dermatan sulfate is a glycosaminoglycan that selectively inhibits the action of thrombin through interaction with heparin cofactor II. Unlike heparin it does not interact with other coagulation factors and is able to inhibit thrombin associated with clots. This property has made dermatan sulfate an attractive candidate as an antithrombotic drug. Previous studies have showed that dermatan sulfate derived from porcine/bovine intestinal mucosa/skin or marine invertebrates is capable of stimulating heparin cofactor II-mediated thrombin inhibition in vitro. This biological activity is reported for the first time in this study using dermatan sulfate derived from mammalian tissues other than intestinal mucosa or skin. Ten different bovine tissues including the aorta, diaphragm, eyes, large and small intestine, esophagus, skin, tendon, tongue, and tongue skin were used to prepare dermatan sulfate-enriched fractions by anion exchange chromatography and acetone precipitation. Heparin cofactor II/dermatan sulfate-mediated thrombin inhibition measured in vitro revealed activity comparable to or higher than the commercial standard with 2-fold differences observed between some tissues. Analysis of the extracted dermatan sulfate using fluorophore-assisted carbohydrate electrophoresis revealed significant differences in the relative percentage of all the mono-sulfated disaccharides, in particular the predominant mammalian disaccharide uronic acid-->N-acetyl-D-galactosamine-4-O-sulfate, confirming previous reports regarding variations in sulfation in dermatan sulfate from different tissues. Overall, these findings demonstrate that dermatan sulfate extracted from a range of bovine tissues exhibits in vitro antithrombin activity equivalent to or higher than that observed for porcine intestinal mucosa, identifying additional sources of dermatan sulfate as potential antithrombotic agents.

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.

A comparison of the beta-D-xyloside, odiparcil, to warfarin in a rat model of venous thrombosis

BACKGROUND

A significant need exists for new chronic oral anticoagulation therapies to replace warfarin. Previous studies have shown that beta-D-xylosides, which prime glycosaminoglycan (GAG) synthesis, have antithrombin and antithrombotic activity. In the following report, a new orally active beta-D-xyloside (odiparcil) has been characterized in a rat model of venous thrombosis and its efficacy and bleeding liability compared to warfarin. Additionally, studies were conducted to investigate odiparcil's ex vivo antithrombin and antiplatelet activity, and also to explore the potential utility of protamine sulfate as a neutralizing agent.

METHODS AND RESULTS

In vivo thrombosis studies were conducted in a rat inferior vena cava model, and bleeding studies in a rat tail transection model. Following oral dosing, warfarin and odiparcil produced dose-related suppression of thrombus formation. A therapeutically relevant dose of warfarin in this model (international normalized ratio; INR 3.0) achieved approximately 65% inhibition of thrombus formation. Warfarin caused dose-related significant increases in bleeding indices. Odiparcil antithrombotic activity was limited by its mechanism to a maximum suppression of thrombus formation of 65-70%, and did not prolong bleeding indices. Additionally, odiparcil-induced heparin cofactor II (HCII)-dependent antithrombin activity was shown to be a function of dermatan sulfate-like GAG production. Other than thrombin-related effects, no odiparcil effects on platelet function were observed. In antidote studies, it was demonstrated that odiparcil-induced antithrombotic activity could be partially neutralized by protamine sulfate.

CONCLUSIONS

These experiments suggest that an antithrombotic approach based upon xyloside induction of circulating GAGs may have the potential to approximate the efficacy of warfarin and yet with a reduced risk to hemostasis.

Dermatan carriers for neovascular transport targeting, deep tumor penetration and improved therapy

A new approach to functional tumor imaging and deep interstitial penetration of therapeutic agents is to target the upregulated transport activities of neovascular endothelium. Agents are formulated with the anionic glycosaminoglycan, 435-type dermatan sulfate (DS 435, 22.2 kDa), chemically enriched for oligosaccharide sequences that confer high heparin cofactor II binding and correlate with high tumor uptake. A magnetic resonance (MR) imaging agent is prepared as self-assembling, 5-nm nanoparticles of Fe(+3):deferoxamine (Fe:Df) bound by strong ion pairing to DS, which forms the outer molecular surface (Zeta potential -39 mV). On intravenous (i.v.) injection, Fe:Df-DS rapidly (<7 min) and selectively targets and transports at high capacity across the neovascular endothelium of large (2-cm) Dunning prostate R3327 AT1 rat tumors; releases from the abluminal surface, due to reversible binding of its multivalent, low-affinity (K(d) 10(-4) to 10(-5)) oligosaccharide ligands; and progressively penetrates the interstitium from its initial site of high uptake in the well-perfused outer tumor rim, into the poorly perfused central subregion. By gamma camera imaging of (67)Ga:Df-DS, the agent avoids normal site uptake and clears through the kidneys with a t(1/2) of 18 min. A therapeutic formulation of DS-doxorubicin (DS-dox) is prepared by aqueous high-pressure homogenization of the drug and DS 435, which produces 11-nm nanoparticles of doxorubicin cores coated with DS (Zeta potential -39 mV) that are stable to lyophilization. Microscopic analysis of tumor sections 3 h after i.v. injection shows much higher overall tumor fluorescence and deeper matrix penetration for DS-dox than conventional doxorubicin (dox): >75 vs. <25 microm between the nearest microvessels. DS-dox also results in enhanced tumor-cell internalization and nuclear localization of the drug. Therapeutic efficacies in established (250 +/- 15 mg) MX-1 human breast tumor xenografts at maximum tolerated doses (MTDs) are (control vehicle, dox, dox-DS) (a) median days to 7-fold tumor growth: 8.3, 25.6 (p = 0.0007), 43.2 (p = 0.0001); (b) complete 90-day tumor regressions: 0/10, 0/10, 4/10. These results demonstrate the potential to develop a novel class of carbohydrate-targeted neovascular transport agents for sensitive, high-resolution (100-microm) MR imaging and improved treatment of larger sized human tumor metastases.

Prolonged bleeding time induced by anticoagulant glycosaminoglycans in dogs is associated with the inhibition of thrombin-induced platelet aggregation

INTRODUCTION

The clinical use of unfractionated heparin (UFH) is complicated by hemorrhage. This has led to a search for safer alternatives, one of which, the recently identified depolymerized holothurian glycosaminoglycan (DHG), causes less bleeding and exhibits a better antithrombotic-hemorrhagic ratio in rats and dogs than UFH and low-molecular-weight heparin (LMWH). In contrast to UFH and LMWH, which exert their anticoagulant effects by inhibiting thrombin in the presence of antithrombin III (AT), DHG exerts its anticoagulant effect by inhibiting the intrinsic factor Xase complex and thrombin in the presence of heparin cofactor II (HCII).

MATERIALS AND METHODS

The hemorrhagic effect of DHG was compared with those of UFH and LMWH in healthy dogs, and the mechanism responsible for prolonging bleeding time was examined both in dogs and with human platelets.

RESULTS

DHG prolonged template-bleeding time in dogs less than UFH and LMWH do. Although the maximum noneffective concentrations of each glycosaminoglycan (GAG) that prolong the bleeding time are almost the same as the concentrations that inhibit thrombin-induced platelet aggregation, they are not related to those that inhibit ADP-induced platelet aggregation. Results of experiments on gel-filtered platelets from humans indicate that the inhibition of thrombin-induced platelet aggregation caused by UFH and LMWH in the presence of AT is more prominent than that caused by DHG with HCII.

CONCLUSIONS

These results suggest that the prolongation of bleeding time caused by GAGs are associated with the inhibition of thrombin-induced platelet aggregation, and DHG may cause less bleeding than UFH and LMWH because of its different thrombin inhibition mechanism in platelet-rich plasma (PRP).

Blood coagulation, fibrinolysis, and markers of endothelial dysfunction in systemic sclerosis

OBJECTIVE

To evaluate the coagulative/fibrinolytic cascade and the circulating markers of the endothelial injury in systemic sclerosis (SSc).

METHOD

Plasma was obtained from 29 patients with SSc and tested for thrombin-antithrombin (TAT), fragments 1+2 (F1+2), dermatansulphate (DS), thrombomodulin (TM), lipoprotein (a) [Lp(a)], von Willebrand factor (vWF), tissue type plasminogen activator (tPA), plasminogen activator inhibitor (PAI), D-dimers, intercellular adhesion molecole-1 (ICAM-1), vascular cell adhesion molecule (VCAM), and E-selectin. The data were correlated with lung (forced vital capacity, diffusing lung capacity for carbon monoxide, vital capacity) and skin (skin score) involvement.

RESULTS

Coagulation was significantly activated (increase in F1+2, P <.001; TAT, P <.01; and Lp(a), P <.05). TM was not significantly different from controls. vWF was significantly increased (P <.01), and its supranormal multimers increased in more than 50% of patients. DS was significantly increased in diffuse cutaneous SSc (P <.01). Fibrinolysis was impaired as shown by reduced D-dimers (P <.01) and decreased levels of PAI (P < 0.01). The markers of endothelial injury were also significantly elevated. DS correlated significantly with forced vital capacity (P <.01) and forced vital capacity ratio (P <.01).

CONCLUSION

Injury to the endothelium reduces endothelial function, as suggested by impairment of fibrinolysis and activation of the coagulative pathway. The loss of the balance between fibrinolysis and coagulation contributes to vessel engulfment with fibrin and breakdown of vessel patency. The increase of circulating DS suggests that this factor may be a new marker of endothelial injury.

Anticoagulant and antiprotease activities of a heparinoid sulfated glucoside-bearing polymer

We studied anticoagulant and antiprotease activities of the poly(glucosyloxyethyl methacrylate) sulfate [poly(GEMA)-sulfate] in plasma and purified enzyme systems in order to evaluate the anticoagulant behavior of a heparin-like sulfated glucoside-bearing polymer. As a result, we found that poly(GEMA)-sulfate can inhibit some coagulation proteases, although its antiprotease behavior differed from those of heparin and dextran sulfate. Poly(GEMA)-sulfate could not enhance antithrombin activity; therefore, we did not observe any significant inhibition of Factor Xa via antithrombin. However, we found that poly(GEMA)-sulfate was able to inhibit thrombin through the activation of heparin cofactor II. In addition, poly(GEMA)-sulfate was able to inhibit Tenase. In our previous research. we found that the anticoagulant activity of poly(GEMA)-sulfate is due primarily to the formation of an insoluble complex with fibrinogen. This paper showed that the antiprotease activities of poly(GEMA)-sulfate contribute to some extent to its anticoagulant activity.

Anticoagulant dermatan sulfate proteoglycan (decorin) in the term human placenta

Normal pregnancy is characterized by increased in vivo thrombin generation. A greater proportion of endogenously generated thrombin is complexed to heparin cofactor II in plasma from pregnant women compared to plasma from nonpregnant ones. The increase in thrombin-heparin cofactor II complexes suggests that the site of the additional thrombin generation is relatively rich in dermatan sulfate. We postulated that the site of thrombin generation may be the placenta since endogenous thrombin generation returns rapidly to normal after delivery. This report describes the isolation and characterization of placental dermatan sulfate proteoglycan from villous tissue of the term human placenta. Placental dermatan sulfate was isolated by guanidine HCI extraction and anion exchange chromatography. The isolated material was found to have anticoagulant activity with a relative activity of approximately 40% of that of a porcine mucosal dermatan sulfate which is undergoing clinical trial as an antithrombotic agent. The dermatan sulfate was present as a proteoglycan with a molecular mass of 90-150 kD. Upon degradation with chondroitin ABC lyase, the core protein was demonstrated to be a doublet with molecular masses of 42 and 44 kD. This core protein reacted with antiserum against the core protein of decorin on Western analysis. The role of this placental dermatan sulfate in local regulation of thrombin in the placenta warrants further study.

Thrombin-inhibitor complexes in the blood during and after delivery

Activation of coagulation leads to generation of thrombin which in turn is inactivated by the formation of thrombin-antithrombin (TAT) complexes, and thrombin-heparin cofactor complexes (T-HCII). These complexes were measured in plasma by ELISA methods. During normal delivery, the median TAT level in ten women increased from 4.1 to 7.8 times the median normal reference level. There was great individual variation, and levels 42 and 56 times normal median were found in two women shortly after normal delivery. The median T-HCII levels increased only moderately from 2.3 to 3.1 times median normal reference. D-dimer values were elevated in 28 out of the 30 samples. In blood sampled 1-2 days after delivery, the median TAT level was 2.5 times the median normal reference. The median T-HCII level was now 5.6 times the median normal reference value. The values were stable during the first 4 days post partum, and there was little difference between those delivered vaginally or by Caesarean section (C-section). D-dimer values were above normal reference in all women, and higher in women delivered by C-section. In conclusion, increasing TAT levels during labour and delivery indicated generation of thrombin which was mainly inactivated by antithrombin. The T-HCII levels increased less during delivery. In the early post partum period, the T-HCII levels were relatively more increased than the TAT levels. These results suggest that intravascularly generated thrombin is preferably inactivated by antithrombin, even in parturient women. In the post partum period, formation of T-HCII complexes was more evident, possibly reflecting extravascular inactivation of thrombin.

Dermatan sulfate as a potential therapeutic agent

1. Dermatan sulfate is a linear, sulfated polysaccharide and is a glycosaminoglycan component of several important proteoglycans. This minireview discusses the biosynthesis, structure and biological function of dermatan sulfate proteoglycans. 2. Dermatan sulfate and its derivatives are being investigated as a new class of anticoagulant and antithrombotic agents. 3. The preparation, chemistry and structure-activity relationship of dermatan sulfate is described. 4. Dermatan sulfate, low molecular weight dermatan sulfate and glycosaminoglycan mixtures containing dermatan sulfate have been used clinically. 5. The future prospects of these agents and other new, potentially useful dermatan sulfate based therapeutics are discussed.

The effect of the beta-D-xyloside naroparcil on circulating plasma glycosaminoglycans. An explanation for its known antithrombotic activity in the rabbit

Beta-D-Xylosides are known to initiate or prime free glycosaminoglycan (GAG) chain synthesis in cell and tissue culture. As such, the effect of the venous antithrombotic beta-D-xyloside, naroparcil, was investigated on the plasma GAG profile in the rabbit after oral administration. Using dose-response experiments, we showed that antithrombin activity via antithrombin III and heparin cofactor II was increased in parallel with GAG plasma levels compared to control. A more detailed qualitative examination of plasma GAGs by cellulose acetate electrophoresis and ion-exchange chromatography, following oral administration of naroparcil at 400 mg/kg, revealed the presence of higher density charged molecules compared to control. The extracted GAGs were found to activate inhibition of thrombin by heparin cofactor II and contained approximately 25% of a dermatan sulfate-like compound (undetectable in control), which could be responsible for the antithrombotic effect. Using radiolabeled naroparcil, we found radiolabeled GAG fractions and the fact that naroparcil was a substrate for galactosyltransferase I, the second enzyme responsible for GAG chain polymerization, suggested that the compound could initiate in vivo the biosynthesis of antithrombotic free GAG chains. This is, to our knowledge, the first description of the in vivo effect of a beta-D-xyloside on GAG biosynthesis; furthermore, this is correlated with an antithrombotic action.

Dermatan sulphate for the treatment of disseminated intravascular coagulation (DIC) in acute leukemia: a randomised, heparin-controlled pilot study

Efficacy and safety of i.v. dermatan sulphate (DS) and heparin (H) in controlling laboratory alterations due to DIC were compared in 10 patients with acute leukaemia, in a prospective, randomised pilot study. The time courses of the coagulation and fibrinolysis markers for DIC were similar in the two treatment groups except for activated partial thromboplastin time and thrombin time, which were prolonged in the H but not in the DS group. Blood product support tended to be greater in the H than in the DS group. DS appears to be as effective as H in controlling thrombin production during leukaemic cytolysis and may represent a safer alternative to H in the management of DIC in acute leukaemia.

Low molecular weight dermatan sulfate as an antithrombotic agent. Structure-activity relationship studies

A structure-activity relationship of low molecular weight dermatan sulfate was undertaken to understand better this new non-heparin, glycosaminoglycan-based antithrombotic agent. A dermatan sulfate prepared from bovine intestinal mucosa [average molecular weight (MWavg) 25,000], and currently in clinical trials as an antithrombotic agent, was used in this study. Dermatan sulfate was partially depolymerized using hydrogen peroxide and copper(II) as catalyst to MWavg 5600 to obtain a low molecular weight dermatan sulfate. This low molecular weight dermatan sulfate was then fractionated by gel permeation chromatography to obtain four subfractions having MWavg 7800, 5500, 4200 and 1950. The dermatan sulfate, low molecular weight dermatan sulfate and its subfractions showed substantially different optical rotations. The 1H-NMR spectroscopic analysis of dermatan sulfate samples showed some differences including increased content of GalpNAc4S6S residues and improved resolution in ring resonances for low molecular weight dermatan sulfate fractions, primarily the result of reduced molecular weight and lowered heterogeneity. Saccharide compositional analysis relied on chondroitin ABC lyase treatment followed by capillary electrophoresis. Polyacrylamide gel-based oligosaccharide mapping was also performed by treating dermatan sulfate samples with chondroitin B, AC and ABC lysases. These analyses showed increased amounts of sulfation as the MWavg decreased. In vitro bioassay showed maximum anti-Xa activity in the 4.2 kDa fraction and maximum heparin cofactor II-mediated anti-IIa activity in the 5.5 kDa fraction. The in vivo antithrombotic activity of these fractions was measured using a modified Wessler stasis thrombosis model. The 4.2 kDa fraction showed greater antithrombotic activity than the other low molecular weight dermatan sulfate fractions, dermatan sulfate, and low molecular weight dermatan sulfate. This enhanced activity may result from several structural features of the 4.2 kDa fraction including: a high content of 4,6- and 2,4-disulfated disaccharide sequences; the requirement of specific chain length; a change in the ratio of iduronic to glucuronic acid; and the presence of chondroitin ABC lyase resistant material.

Dermatan sulfate from beef mucosa: structure, physicochemical and biological properties of fractions prepared by chemical depolymerization and anion-exchange chromatography

Dermatan sulfate was extracted and purified from beef intestinal mucosa. The structure and physicochemical properties were evaluated by different techniques, such as, disaccharide pattern, relative molecular mass, sulfate-to-carboxyl ratio, and electrophoretic profile in agarose electrophoresis. The biological activity was evaluated as heparin cofactor II activity (HCII activity). The purity of dermatan sulfate was carefully evaluated by specific enzymatic cleavage, agarose electrophoresis, and HPLC. Different relative molecular masses of dermatan sulfate, from 25,000 to 2000, were prepared by chemical degradation. The structures and physicochemical properties were checked to exclude a possible desulfation process. The HCII activities were evaluated for different relative molecular mass of dermatan sulfate. The capacity of chondroitinase ABC to cleave different relative molecular masses of dermatan sulfate was also studied. Native dermatan sulfate was fractionated according to charge density. Different fractions were obtained and analysed for disaccharide pattern, relative molecular mass, sulfate-to-carboxyl ratio, and HCII activities.

A high performance liquid chromatography method for the determination of glycosaminoglycans in human blood

A method is described for the determination of plasma and serum glycosaminoglycans, which can be used in any laboratory equipped with an HPLC system. It is based on the sequential application of chondroitinases AC and ABC and separation of the resulting disaccharides by high-performance liquid chromatography. All reagents are commercially available. This simple and rapid separation yields an accurate quantification and an exact distribution pattern. The determination of glycosaminoglycan disaccharides is linear between 7 and 7000 mumol/l with coefficients of variation between 3.0 and 7.7% for serum and between 2 and 14% for plasma. The recovery of the assay ranged from 93 to 106% for different concentrations of glycosaminoglycan disaccharides. This HPLC method may therefore be considered as a candidate reference method.

The pharmacokinetics and pharmacodynamics of dermatan sulphate MF701 during haemodialysis for chronic renal failure

Single i.v. bolus doses of dermatan sulphate MF701 were administered before the onset of haemodialysis to patients with chronic renal failure, to prevent clotting in the extracorporeal circuit. Six patients received 2 mg kg-1; six were given 2.5 and 3 mg kg-1; 13 received 4.5 and 6 mg kg-1. Plasma MF701 concentrations (chromogenic assay), activated partial thromboplastin time (APTT) and plasma markers of coagulation and platelet activation (TAT and beta-TG) were measured over 4 or 8 h from the onset of dialysis. The disposition of MF701 was described by a monoexponential function. C(0) and AUC values increased proportionally with dose. Volumes of distribution (approximately 4 l) were dose-independent. Half-lives showed a non significant increase with dose (from 2.2 to 3.1 h) and were 2.5-3 times longer than those reported for healthy subjects. There was a significant correlation between plasma MF701 concentration and its effects in prolonging APTT and suppressing TAT and beta-TG generation during dialysis.

Influence of molecular weight upon the anticoagulant and pharmacokinetic properties of dermatan sulfate in the rabbit

In order to improve the pharmacokinetic properties of unfractionated dermatan sulfate (UDS, mean MW: 25kD), the disposition of 4 low molecular weight dermatan sulfates (LMWDS) with a mean MW ranging from 15 to 4 kD was investigated in the rabbit. In comparison with UDS, it was established that after intravenous administration, the half-life of disappearance, the distribution volume and the clearance of the biological activity increased as the mean molecular weight decreased. After subcutaneous administration, the bioavailability of the 4 LMWDS was improved in comparison with that of UDS, but large inter-animal variations were recorded for LMWDS having a mean MW over 9 kD. Therefore the best compromise between biological activity, clearance, half-life of disappearance, bioavailability and reproducibility after subcutaneous administration should be a compound having a MW ranging from 4 to 9 kD.

Dermatan sulphate: a safe approach to prevention of postoperative deep vein thrombosis

To assess the efficacy and safety of dermatan sulphate (MF 701) in preventing postoperative deep vein thrombosis (DVT), 324 patients aged 40 years or over undergoing elective major general surgical operations were included in a randomized trial comparing MF 701 (100 mg intramuscularly once a day) with unfractionated calcium heparin (UFH, 5000 units subcutaneously three times daily). Both treatments were initiated before operation and continued until discharge. In all, 316 patients were included in the analysis (MF 701, 157; UFH, 159). Serial impedance plethysmography was performed in all patients; a 125I-radiolabelled fibrinogen uptake test was added to impedance plethysmography in a randomized subsample of 62 patients (MF 701, 28; UFH, 34). Positivity in either test was confirmed where possible by venography. DVT was diagnosed by venography or, when this could not be performed, by positivity of either impedance plethysmography or fibrinogen uptake test. The incidence of DVT was 3.1 per cent (patients receiving MF 701) and 1.6 per cent (those receiving UFH) in patients undergoing impedance plethysmography alone, and 7.1 and 11.8 per cent, respectively, in those undergoing both impedance plethysmography and fibrinogen uptake test; in neither case was the difference between treatments statistically significant. There were five in-hospital deaths, two in patients receiving MF 701 and three in patients on UFH. The incidence of clinically overt haemorrhage was 5.7 per cent in patients on MF 701 and 17.6 per cent in those on UFH (P less than 0.01). Postoperative transfusions and reoperations due to bleeding were significantly less frequent in patients receiving MF 701. Mortality rates at 3 months were similar for the two treatment groups. Compared with standard prophylaxis using UFH, MF 701 showed a similar efficacy with a significantly greater safety.

Antithrombotic activity, bleeding effect and pharmacodynamics of a succinyl derivative of dermatan sulphate in rabbits

This paper compares the pharmacological properties of a new succinyl dermatan sulphate derivative (Suc-DS) to those of the natural dermatan sulphate (DS). Suc-DS was on average 2-3 times more potent than DS in catalysing the inhibition of thrombin by heparin cofactor II and in prolonging the activated partial thromboplastin time and the thrombin clotting time. After bolus injection, Suc-DS was also 2-3 times more potent than DS to prevent experimental venous thrombosis in a Wessler model. Thromboplastin or human serum were used as the thrombogenic stimulus. In contrast, the bleeding effect assessed by rat tail transection technique was comparable. After bolus intravenous injection, the pharmacodynamics of Suc-DS indicated a lower volume of distribution, which was close to the plasma volume, and a slightly lower clearance of elimination. Therefore this chemical alteration of natural DS yields a new compound with an improved antithrombotic benefit/haemorrhagic risk ratio.

Placental transfer of glycosaminoglycans in the human perfused placental cotyledon model

Placental transfer of unfractionated heparin (UH), of low molecular weight heparin CY 216 (LMWH) and of Dermatan sulphate (DS) was studied using the human perfused placental cotyledon model. Two different techniques were used to assess the transfer: labelled molecules and biological activities as measured by antifactor Xa or antifactor IIa activities. No biological activity was present in the fetal circulation, for any of the drugs used; however, very low fractions of the perfused radioactivity were recorded, 0.76% +/- 0.36%, 1.46% +/- 1.44% and 2.37% +/- 0.89% for DS, UH and LMWH, respectively.

Structural features of dermatan sulfates and their relationship to anticoagulant and antithrombotic activities

Dermatan sulfate is a polydisperse, microheterogeneous sufated copolymer of N-acetyl-D-galactopyranose and idopyranosyluronic acid that is currently under clinical investigation as a new antithrombotic agent. The structure and activity of two pairs of dermatan sulfates, isolated from bovine and porcine mucosa, were studied. One dermatan sulfate from each species demonstrated high in vivo antithrombotic activity in the rat vena cava assay. The in vitro anticoagulant activity of each dermatan sulfate was determined using activated partial thromboplastin time (APTT), thrombin time (TT) (5 units), calcium thrombin time (CaTT) (5 units), Heptest, anti-factor Xa and anti-factor IIa antithrombin assays and heparin cofactor II amidolytic assays. The coagulation-based assays gave the best correlation to in vivo antithrombotic activity. The physical and chemical properties of each dermatan sulfate were determined using 1H-NMR and 13C-NMR spectroscopy, molecular weight determination, potentiometric titration, chemical degradative analysis, chondroitin lyase degradative analysis and oligosaccharide mapping. These analyses indicated that the major difference between dermatan sulfates from a particular species having high and low in vivo antithrombotic activity was their iduronic acid content. The relation between increased iduronic acid content and increased in vivo antithrombotic activity may be the result of the conformational flexibility of this residue.

The pharmacokinetics of dermatan sulphate MF701 in healthy human volunteers

1. The pharmacokinetics of dermatan sulphate MF701 were studied in 12 healthy males after administration of single intravenous bolus (200 mg), intramuscular (100 and 300 mg) and oral (1 g) doses. The study was conducted according to a within-subject crossover design in two paired blocks. 2. Plasma drug concentrations were measured using a competitive binding assay and a range of biological activity assays, including a sensitive catalysed thrombin inhibition test. 3. Following intravenous administration, plasma concentrations of dermatan sulphate determined by competitive binding assay were described by a two-compartment open model with an initial t1/2, in of 0.6 h and a t1/2,z of 7.5 h. Biological activity assays were insufficiently sensitive to detect the second phase, and therefore yielded apparent monoexponential kinetics. 4. After intramuscular injection the apparent bioavailability of dermatan sulphate was 16-20%. Plasma drug concentrations increased in proportion to dose when measured by competitive binding assay. Low concentrations persisted for more than 24 h at the higher dose, and these may prove therapeutically relevant on chronic administration. 5. We confirm that dermatan sulphate is the only glycosaminoglycan known to generate significant plasma concentrations following oral administration. Oral bioavailability was estimated to be 7%.

Antithrombotic potencies of heparins in relation to their antifactor Xa and antithrombin activities: an experimental study in two models of thrombosis in the rabbit

Our purpose was to determine the relative contribution of the antifactor Xa and antithrombin activities of heparin to its antithrombotic potency. The antithrombotic activities of unfractionated heparin (UH), two low molecular weight heparins (LMWH, CY 216 and CY 222) with increasing anti-factor Xa/antithrombin ratio and a synthetic pentasaccharide (PS) with high affinity to antithrombin III and no antithrombin activity were evaluated. In the Wessler-thromboplastin model, the most potent antithrombotic agent, on a weight basis, was UH followed by CY 216, CY 222 and the PS which was 40 times less potent than UH. On an antithrombin unit basis, the antithrombotic potencies of UH, CY 216 and of CY 222 were equivalent. Thus, in this model, the antithrombotic effect results from the catalytic action of UH or LMWH on thrombin inhibition. In the Wessler-serum model, on a weight basis, the antithrombotic effectiveness of UH was unchanged, those of CY 216 and CY 222 were doubled, and that of the PS was increased 10 times. On an anti-factor Xa unit basis, CY 216 was as effective as UH, and PS as effective as CY 222. On an antithrombin unit basis, CY 216 and CY 222 were equivalent and more potent than UH. Thus, in this model, the antifactor Xa activity of heparin becomes important for its antithrombotic property. After a single subcutaneous injection of 1000 antifactor Xa U/kg, the antithrombotic effects of UH were maintained for more than 14 h in the two models. After injection of the same dose of CY 216 significant antithrombotic effects were observed only for 9 h, in the Wessler-thromboplastin model but for 18 h in the Wessler-serum model. At that time, no detectable antithrombin activity was measurable in the plasma while 0.11 units of antifactor Xa activity/ml was detected. Thus, the relative contribution of the anti-factor Xa and antithrombin activities to the antithrombotic effect of a LMWH differs according to the nature of the thrombogenic stimulus.

Neutralization of dermatan sulfate in vitro and in vivo by protamine sulfate and polybrene

The neutralization of the anticoagulant, anti-thrombin, and bleeding effects of dermatan sulfate (DS), a potential antithrombotic agent, was investigated. Protamine sulfate (PS) and hexadimethrine bromide (Polybrene), which reverse the anticoagulant effect of heparin, also neutralized DS in vitro. In human plasma, polybrene was approximately 3 times more active on a weight basis than PS for neutralizing DS (1.5 micrograms polybrene inhibits 1 microgram DS). Intravenous administration of polybrene to rabbits pretreated with DS in a 1:1 weight ratio immediately neutralized 90% of DS and this effect was stable with time. In contrast, PS in a weight ratio of 6:1 (PS to DS) only neutralized 50% of DS injected. When plasma DS concentrations were maintained by continuous infusion between 3 and 15 micrograms/ml, a bolus of polybrene 0.25 mg/kg induced an immediate drop of about 4 micrograms/ml but initial values of DS were recovered within 20 min. PS was again much less effective than polybrene for neutralizing DS. The bleeding effect of DS and its correction by polybrene was studied by using the rat tail transection model. Very large doses of DS (greater than 10 mg/kg) were required to get a modest prolongation of bleeding time. The injection of equivalent doses of polybrene in animals pretreated by DS induced a strong bleeding effect associated with a drop in platelet and leukocyte counts. Animal models are thus inappropriate for investigating the correction of DS-induced bleeding, because high doses of both DS and neutralizing agents are required in these models. Our results indicate that, provided the doses of neutralizing agents remain below their established levels of toxicity in man, DS could if necessary be neutralized completely by polybrene and partially by PS.