The effect of dermatan sulfate on in vitro human plasma coagulation, platelet aggregation and beta TG/PF4 release

Thrombin-activated thrombelastography for evaluation of thrombin interaction with thrombin inhibitors

For intravenous anticoagulation, heparin has been the mainstay drug, but its use may be contraindicated in heparin-induced thrombocytopenia and thrombosis. Heparin alternatives including direct thrombin inhibitors are available, but clotting assays (e.g. partial thromboplastin time) measure the time required to form fibrin gel when only a small amount of thrombin is generated. It was hypothesized that the extent of thrombin inhibition varies among inhibitors, and thrombin-activated thrombelastography would provide useful data on therapeutic responses to thrombin inhibitors. Thrombin was added (0-100 nmol/l final concentration) to nonrecalcified whole blood to evaluate clot formation on thrombelastography. Effects of direct thrombin inhibitors (argatroban 3.75 microg/ml, bivalirudin 15 microg/ml, and lepirudin 3.0 microg/ml), and heparin cofactor II activator and dermatan disulfate (20 microg/ml) were evaluated in the presence of 100 nmol/l thrombin. The interactions of thrombin and respective inhibitors were also compared by fluorogenic thrombin substrate cleavage. Increasing concentrations of thrombin progressively shortened the lag time and increased viscoelasticity on thrombelastography. Only 20 nmol/l thrombin caused instantaneous clotting, but maximal viscoelastic force was obtained at 50-100 nmol/l thrombin. All thrombin inhibitors prolonged the lag time (lepirudin > bivalirudin > argatroban = dermatan disulfate), but full recovery of thrombelastography viscoelasticity was observed with argatroban and bivalirudin. Lepirudin abrogated clotting, and dermatan disulfate suppressed clot development on thrombelastography. Thrombin substrate cleavage was observed only for bivalirudin, and heparin cofactor II without dermatan disulfate. The modified thrombelastography technique using nonrecalcified whole blood may be useful in evaluating the extent and reversibility of thrombin blockade with direct or indirect thrombin inhibitors.

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.

Effects of dermatan sulfate, a heparin cofactor II mediated thrombin inhibitor, on the endotoxin-induced disseminated intravascular coagulation model in the rat: comparison with low-molecular weight heparin, nafamostat mesilate and argathroban

Effects of dermatan sulfate (DS) on the endotoxin-induced disseminated intravascular coagulation (DIC) rat model were compared with those of low-molecular weight heparin (LMWH), nafamostat mesilate (NM) and argathroban (AR). At doses of 5, 10 or 20 mg/kg/4 hr, DS significantly ameliorated the decrease of fibrinogen (Fbg), the increase of fibrin-fibrinogen degradation products (FDP) and except at the highest dose (20 mg/kg/4 hr), the prolongation of thrombin clotting time (TCT). It also decreased the glomerular fibrin deposits (%GFD) at doses of 10 or 20 mg/kg/4 hr. LMWH suppressed the decrease of Fbg and the increase of FDP at doses of 1.4 or 2.8 mg/kg/4 hr. Only the highest dose of LMWH suppressed the decrease of the platelet count (PL), the prolongation of prothrombin time, and improved the %GFD. AR suppressed the decrease of PL and improved the %GFD. At the dose required to improve the %GFD, DS (5, 10 mg/kg/4 hr) significantly suppressed the prolongation of TCT, which is related to the bleeding frequency, while LMWH and AR further increased the prolongation of the TCT. These results suggest that DS has potential as a therapeutic drug with a lower hemorrhagic risk as compared with LMWH and AR in the treatment of DIC.

Pharmacology of desmin (low molecular weight dermatan sulphate) in healthy volunteers following intravenous bolus administration of different dosages (200, 400, 800 mg)

Eight healthy volunteers (6 males, 2 females, mean age 31.6 yrs), were administered--on three separate days--200, 400 and 800 mg of a new low molecular weight Dermatan sulphate (Desmin), given as a single i.v. bolus (2 min.) injection. Before each administration and 10, 20, 30 min., 1, 2, 4, 8, 12, 24 hours after, blood samples were drawn and the following coagulative assays performed: aPTT (activated Partial Thromboplastin Time), TT (Thrombin Time), anti Xa (Xa Factor inhibition), Heptest, Stachrom D.S.. Furthermore, a kinetic analysis was performed on the activity curves calculated on the Heptest and Stachrom data. Plasma peak values and half lives of the parameters checked showed a clear dose-effect relationship. aPTT and TT showed very short-lasting variations and the inhibition of Factor Xa was moderate, but significant. The most evident and specific effects of Desmin were those on Heptest and Stachrom D.S.: both tests were influenced in a clear-cut and dose-dependent way, mainly as a consequence of the action of Desmin on HCII, with partially different kinetic patterns. A series of in vitro experiments proved an anti Xa effect of Desmin, mediated by antithrombin III, well above the possible interference of the small (< 1%) heparin contaminants in Desmin. An even more marked anti Xa activity was seen in the in vivo study, an observation so far unrecognized for this type of drug: some possible interpretations of this fact are discussed.

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.

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.