Thrombolytic Properties in a Rabbit Jugular Vein Thrombosis Model of a Tissue-type Plasminogen Activator Mutant Lacking the Growth Factor- and Kringle 1-Domains

SummaryIn this study, we aimed at improving the therapeutic index of tissue- type Plasminogen Activator (t-PA) as thrombolytic agent in the treatment of myocardial infarction. Liposome-encapsulated t-PA was tested in a rabbit jugular vein thrombosis model: administration of free t-PA (t-PA) as a bolus injection in the ear vein was compared to a similar administration of liposomal t-PA (t-PA-lip), liposomal t-PA in plasminogen-coated liposomes (Plg-t-PA-lip), a mixture of free t-PA and empty liposomes (t-PA+empty lip) and a saline-blank (blank) in terms of thrombolytic activity and side effects.Liposomal t-PA (t-PA-lip/Plg-t-PA-lip) showed a significantly better thrombolysis efficiency than equimolar doses of free t-PA (t-PA/ t-PA+ empty lip): about 0.24 mg/kg of liposomal t-PA practically equalled the lysis-activity of a dose of free t-PA of 1.0 mg/kg (t-PAlmg/kg). On the other hand, liposome encapsulation did not affect the systemic activation of alpha2-antiplasmin and plasminogen by t-PA.We conclude that for this model an improvement in thrombolytic efficacy of t-PA is achieved by liposome encapsulation of t-PA. As t-PA-lip and Plg-t-PA-lip -treatment induced similar results, targeting of liposomal t-PA by coupled glu-Plg remains a topic to be optimized in future studies.

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Thrombolytic properties of human tissue-type plasminogen activator, single-chain urokinase-type plasminogen activator, and synergistic combinations in venous thrombosis models in dogs and rabbits

Blood ◽

10.1182/blood.v73.5.1207.bloodjournal7351207 ◽

1989 ◽

Vol 73 (5) ◽

pp. 1207-1212

Author(s):

DJ Spriggs ◽

JM Stassen ◽

Y Hashimoto ◽

D Collen

Keyword(s):

Plasminogen Activator ◽

Rabbit Model ◽

Synergistic Interaction ◽

Tissue Type ◽

Single Chain ◽

Tissue Type Plasminogen Activator ◽

Vein Thrombosis ◽

Thrombosis Model ◽

Type Plasminogen Activator ◽

Urokinase Type Plasminogen Activator

Thrombolysis with single and combined four-hour intravenous (IV) infusions of recombinant tissue-type plasminogen activator (rt-PA), recombinant single-chain urokinase-type plasminogen activator of 54,000 molecular weight (mol wt) (rscu-PA), and rscu-PA-32 kD, an rscu-PA derivative of 32,000 mol wt was studied in a femoral vein thrombosis model in the dog and in a jugular vein thrombosis model in the rabbit. In both species, the dose-response curves were linear, and no systemic activation of the fibrinolytic system or fibrinogen breakdown was observed. The steady-state levels of rt-PA-, rscu-PA-, and rscu-PA-32 kD-related antigens in plasma were proportional to the infusion rates. In the dog model, 25% lysis was obtained with 0.11 mg/kg rt-PA, 0.8 mg/kg rscu-PA, and 0.37 mg/kg rscu-PA-32 kD. Combinations of rt-PA and rscu-PA were 2.6 times more active (P less than .005) than anticipated on the basis of their pharmacologic additive effects, whereas combinations of rt-PA and rscu-PA-32 kD were 2.7 times more active (P less than .05). In the rabbit model, 25% lysis was obtained with 0.24 mg/kg rt-PA, 0.75 mg/kg rscu-PA, and 1.25 mg/kg rscu-PA-32 kD. Combinations of rt-PA and rscu-PA have a fivefold synergistic interaction, but surprisingly no synergism was observed between rt-PA and rscu-PA-32 kD. This study shows that synergism between rt-PA and rscu-PA occurs both in rabbits and dogs in a relatively narrow concentration range that allows a fractional reduction of the total equipotent dose by a factor of 2.5-fold to fivefold. Combination therapy is not associated with systemic fibrinolytic activation. This range of synergistic interaction, although limited, may be useful in devising the best thrombolytic therapy for patients with thromboembolic disease.

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Effects of Hirudin and Heparin on the Binding of New Fibrin to the Thrombus in t-PA Treated Rabbits

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646465 ◽

1991 ◽

Vol 66 (05) ◽

pp. 592-597 ◽

Cited By ~ 14

Author(s):

Giancarlo Agnelli ◽

Claudia Pascucci ◽

Benilde Cosmi ◽

Giuseppe G Nenci

Keyword(s):

Jugular Vein ◽

Tissue Type ◽

Clinical Settings ◽

Jugular Vein Thrombosis ◽

Recombinant Hirudin ◽

Vein Thrombosis ◽

Positive Effects ◽

Thrombosis Model ◽

Type Plasminogen Activator ◽

The Difference

SummaryThe aim of this study was to compare the ability of heparin and recombinant hirudin (r-hirudin) in preventing accretion of new fibrin on thrombi during and after treatment with tissue-type plasminogen activator (t-PA) and in enhancing t-PA induced fibrinolysis in a rabbit jugular vein thrombosis model. Heparin and r-hirudin were infused at doses capable of doubling aPTT. In the fibrin accretion inhibition experiments t-PA was infused over 3 h at a dose of 0.2 mg/kg along with saline or heparin, 0.75 mg/ kg or r-hirudin, 1.25 mg/kg. In rabbits treated with t-PA plus saline, heparin or r-hirudin, an accumulation of 125I-fibrinogen on the thrombi of 52.5 ±5.1 εg, 49.5 ± 5.6 εg and 23.5 ± 3.5 εg was observed, respectively, the difference between r-hirudin and both saline and heparin being statistically significant (p <0.01). The inhibition of fibrin accretion on the thrombi induced by r-hirudin persists for at least 9 h after the end of the infusion. By that time r-hirudin has been cleared from the circulation and aPTT has returned to the baseline level for at least 8 h. t-PA, 0.2, 0.4, and 1 mg/kg, infused with saline produced 34 ± 6%, 52 ± 5% and 79 ± 8% lysis of pre-formed thrombi, respectively. The same doses of t-PA infused with heparin, 0.75 mg/kg, produced 32 ± 3%, 54 ± 5% and 78 ± 6% fibrinolysis, respectively and infused with r-hirudin, 1.25 mg/kg, 38 ± 3%, 57 ± 5% and 82 ± 8%, respectively. Thus, no differences in fibrinolysis were observed among the groups of rabbits treated with heparin, r-hirudin and saline receiving the same dose of t-PA. When thrombolysis was assessed by thrombus weight treatment with t-PA and r-hirudin was more effective than treatment with t-PA and saline or heparin. The positive effects of r-hirudin on t-PA induced thrombolysis we observed deserve to be confirmed in clinical settings.

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Thrombolytic properties of human tissue-type plasminogen activator, single-chain urokinase-type plasminogen activator, and synergistic combinations in venous thrombosis models in dogs and rabbits

Blood ◽

10.1182/blood.v73.5.1207.1207 ◽

1989 ◽

Vol 73 (5) ◽

pp. 1207-1212 ◽

Cited By ~ 19

Author(s):

DJ Spriggs ◽

JM Stassen ◽

Y Hashimoto ◽

D Collen

Keyword(s):

Plasminogen Activator ◽

Rabbit Model ◽

Synergistic Interaction ◽

Tissue Type ◽

Single Chain ◽

Tissue Type Plasminogen Activator ◽

Vein Thrombosis ◽

Thrombosis Model ◽

Type Plasminogen Activator ◽

Urokinase Type Plasminogen Activator

Abstract Thrombolysis with single and combined four-hour intravenous (IV) infusions of recombinant tissue-type plasminogen activator (rt-PA), recombinant single-chain urokinase-type plasminogen activator of 54,000 molecular weight (mol wt) (rscu-PA), and rscu-PA-32 kD, an rscu-PA derivative of 32,000 mol wt was studied in a femoral vein thrombosis model in the dog and in a jugular vein thrombosis model in the rabbit. In both species, the dose-response curves were linear, and no systemic activation of the fibrinolytic system or fibrinogen breakdown was observed. The steady-state levels of rt-PA-, rscu-PA-, and rscu-PA-32 kD-related antigens in plasma were proportional to the infusion rates. In the dog model, 25% lysis was obtained with 0.11 mg/kg rt-PA, 0.8 mg/kg rscu-PA, and 0.37 mg/kg rscu-PA-32 kD. Combinations of rt-PA and rscu-PA were 2.6 times more active (P less than .005) than anticipated on the basis of their pharmacologic additive effects, whereas combinations of rt-PA and rscu-PA-32 kD were 2.7 times more active (P less than .05). In the rabbit model, 25% lysis was obtained with 0.24 mg/kg rt-PA, 0.75 mg/kg rscu-PA, and 1.25 mg/kg rscu-PA-32 kD. Combinations of rt-PA and rscu-PA have a fivefold synergistic interaction, but surprisingly no synergism was observed between rt-PA and rscu-PA-32 kD. This study shows that synergism between rt-PA and rscu-PA occurs both in rabbits and dogs in a relatively narrow concentration range that allows a fractional reduction of the total equipotent dose by a factor of 2.5-fold to fivefold. Combination therapy is not associated with systemic fibrinolytic activation. This range of synergistic interaction, although limited, may be useful in devising the best thrombolytic therapy for patients with thromboembolic disease.

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4 Interaction of recombinant tissue-type plasminogen activator (rt-PA) and murine anti-platelet GPIIb/IIIa monoclonal antibody in a canine femoral vein thrombosis model

Fibrinolysis and Proteolysis ◽

10.1016/0268-9499(88)90004-5 ◽

1988 ◽

Vol 2 ◽

pp. 2

Author(s):

D. Spriggs ◽

H.K. Gold ◽

Y. Hashimoto ◽

L. Vanhoutte ◽

J. Vermylen ◽

...

Keyword(s):

Monoclonal Antibody ◽

Plasminogen Activator ◽

Femoral Vein ◽

Tissue Type ◽

Tissue Type Plasminogen Activator ◽

Vein Thrombosis ◽

Thrombosis Model ◽

Type Plasminogen Activator

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Biological and Thrombolytic Properties of Proenzyme and Active Forms of Human Urokinase – III. Thrombolytic Properties of Natural and Recombinant Urokinase in Rabbits with Experimental Jugular Vein Thrombosis

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661129 ◽

1984 ◽

Vol 52 (01) ◽

pp. 027-030 ◽

Cited By ~ 77

Author(s):

D Collen ◽

J M Stassen ◽

M Blaber ◽

M Winkler ◽

M Verstraete

Keyword(s):

Jugular Vein ◽

Fibrinolytic System ◽

Tissue Type ◽

Jugular Vein Thrombosis ◽

Thrombolytic Activity ◽

Tissue Type Plasminogen Activator ◽

Vein Thrombosis ◽

Time Period ◽

Type Plasminogen Activator ◽

Systemic Side Effects

SummaryThe thrombolytic properties of recombinant pro-urokinase (Rec-pro-UK), recombinant active urokinase (Rec-UK) and natural urinary urokinase (Nat-UK) were compared with those of tissue-type plasminogen activator (t-PA) in rabbits with a radiolabeled thrombus in the jugular vein. The thrombolytic agents were infused intravenously over a time period of 4 hr and the extent of thrombolysis measured two hours later.In control animals the extent of thrombolysis was 11 ± 2% (n=8) after 6 hr. Nat-UK and Rec-UK had very similar thrombolytic properties. Significant thrombolysis was only obtained with infusion of 240,000 IU per kg (41 ± 2%, n=4 for Nat-UK and 37 ± 4%, n=4 for Rec-UK) and this was associated with a marked systemic activation of the fibrinolytic system, as evidenced by consumption of plasminogen and α2-antiplasmin and fibrinogen breakdown.Infusion of Rec-pro-UK induced thrombolysis at a dose of 60,000 IU per kg (44 ± 8%, n=3) but without associated systemic activation of the fibrinolytic system. In this respect the properties of Rec-pro-UK were similar to those of t-PA, which, however, had a 2- to 4-fold higher specific thrombolytic activity (30,000 IU/ kg yielding 48 ± 1% lysis, n=4).It is concluded that Rec-UK has very similar thrombolytic properties as Nat-UK and that Rec-pro-UK has a beter thrombus- selectivity and less systemic side effects than the active enzymes.

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