An animal model of fibrinolytic bleeding based on the rebleed phenomenon: Application to a study of vulnerability of hemostatic plugs of different age

Marder, Victor J.; Shortell, Cynthia K.; Fitzpatrick, Patricia A.; Kim, Cadence; Oxley, David

doi:10.1016/0049-3848(92)90255-9

Cited by 22 publications

(16 citation statements)

References 15 publications

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“…At thrombolytic doses, BB‐10153 was shown to have no effect on rabbit ear bleeding time and there was no re‐bleeding, whereas t‐PA increased it 6‐fold and did produce re‐bleeding. It should be noted that the model we used was different from ones previously described, in which puncture wounds are made in regions of the ear devoid of visible blood vessels [24], in that the incision was made in the marginal ear vein to resemble more closely the vascular access sites used in clinical thrombolytic therapy. It was also observed during the thrombolysis experiments that BB‐10153 did not cause bleeding at cauterized surgical sites and vascular access sites associated with the models, while t‐PA caused significant bleeding; indeed, this bleeding prevented dosing with t‐PA above 3 mg kg −1 .…”

Section: Discussionmentioning

confidence: 99%

Thrombolytic activity of BB-10153, a thrombin-activatable plasminogen

Comer

Cackett

Gladwell

et al. 2005

Journal of Thrombosis and Haemostasis

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Summary. Background: BB‐10153 is an engineered variant of human plasminogen, modified to be activated to plasmin by thrombin. Thrombin‐activatable plasminogen was designed as a novel thrombolytic agent which would persist in the blood as a prodrug and be activated to plasmin only at fresh or forming thrombi by the thrombin that is tightly localized there. We previously described the construction of several thrombin‐activatable plasminogens and their in vitro clot lysis activity. Objectives and methods: The current study was an examination of the thrombolytic properties of BB‐10153 in vivo; comparison was made with tissue‐type plasminogen activator (t‐PA) in a femoral artery copper coil thrombosis model in the anesthetized dog and rabbit. Heparin was not coadministered so that the fundamental activity of the agents could be compared. Results: BB‐10153, administered as an intravenous bolus of 5 mg kg−1 in the dog and 10 mg kg−1 in the rabbit, produced a comparable incidence of reperfusion to 3 mg kg−1 t‐PA. Reocclusion at these doses occurred in 4/4 dogs and 5/7 rabbits treated with t‐PA and in 2/6 dogs and 0/10 rabbits treated with BB‐10153. There was no reocclusion in three dogs dosed with 10 mg kg−1 BB‐10153. BB‐10153 did not affect plasma α2‐antiplasmin levels or the bleeding time, whereas 3 mg kg−1 t‐PA caused marked depletion of α2‐antiplasmin and fibrinogen and increased the bleeding time. The plasma half‐life of BB‐10153 was 3–4 h. Conclusions: The long half‐life and thrombus‐selective thrombolytic activity of BB‐10153 might allow it to overcome the bleeding and reocclusion shortfalls in the performance of current thrombolytics.

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Section: Discussionmentioning

confidence: 99%

Thrombolytic activity of BB-10153, a thrombin-activatable plasminogen

Comer

Cackett

Gladwell

et al. 2005

Journal of Thrombosis and Haemostasis

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“…14,18 The experimental protocol was approved by the Animal Care and Use Committee at Los Angeles Orthopaedic Hospital. Thirty New Zealand white rabbits (Hazelton Research Products, Denver, PA) weighing 3.5 to 4.5 kg were assigned to 6 treatment groups in a randomized, prospective manner.…”

Section: Methodsmentioning

confidence: 99%

“…Observations regarding these laboratory end points could provide insights for the pathophysiology of plasmin-induced bleeding and for its prevention. Accordingly, this study uses an animal model of fibrinolytic hemorrhage 14 to evaluate escalating dosages of plasmin, above the 2-mg/kg dose that dissolves experimental thrombi, 13 to determine if a threshold dose for bleeding exists and if such bleeding can be predicted or at least explained by changes in blood coagulation or fibrinolytic parameters. As control, and to test what dose of TPA can be administered without inducing bleeding, TPA at progressively lower doses, below that which is optimal for thrombolysis (1 mg/kg), 13 were compared for bleeding manifestations and for blood coagulation parameters.…”

Section: Introductionmentioning

confidence: 99%

Distinct dose-dependent effects of plasmin and TPA on coagulation and hemorrhage

Stewart

Kong

Novokhatny

et al. 2003

Blood

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All thrombolytic agents in current clinical usage are plasminogen activators. Although effective, plasminogen activators uniformly increase the risk of bleeding complications, especially intracranial hemorrhage, and no laboratory test is applicable to avoid such bleeding. We report results of a randomized, blinded, dose-ranging comparison of tissue-type plasminogen activator (TPA) with a directacting thrombolytic agent, plasmin, in an animal model of fibrinolytic hemorrhage. This study focuses on the role of plasma coagulation factors in hemostatic competence. Plasmin at 4-fold, 6-fold, and 8-fold the thrombolytic dose (1 mg/kg) induced a dose-dependent effect on coagulation, depleting antiplasmin activity completely, then degrading fibrinogen and factor VIII. However, even with complete consumption of antiplasmin and decreases in fibrinogen and factor VIII to 20% of initial activity, excessive bleeding did not occur. Bleeding occurred only at 8-fold the thrombolytic dose, on complete depletion of fibrinogen and factor VIII, manifest as prolonged primary bleeding, but with minimal effect on stable hemostatic sites. Although TPA had minimal effect on coagulation, hemostasis was disrupted in a dose-dependent manner, even at 25% of the thrombolytic dose (1 mg/kg), manifest as rebleeding from hemostatically stable ear puncture sites. Plasmin degrades plasma fibrinogen and factor VIII in a dose-dependent manner, but it does not disrupt hemostasis until clotting factors are completely depleted, at an 8-fold higher dose than is needed for thrombolysis. Plasmin has a 6-fold margin of safety, in contrast with TPA, which causes hemorrhage at thrombolytic dosages. (Blood.

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“…Secondly, after removing the hair from the dorsal surface of each ear, a full thickness incision was made 3–5 mm in length using a #11 scalpel blade in an area devoid of visible vessels, as previously described in rabbits [10]. The bleeding points on both surfaces of each ear were dabbed at intervals until hemostasis.…”

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confidence: 99%

Thrombolysis vs. bleeding from hemostatic sites by a prourokinase mutant compared with tissue plasminogen activator

Gurewich

Pannell

Simmons-Byrd

et al. 2006

Journal of Thrombosis and Haemostasis

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Summary. Background: A single site mutant (M5) of prourokinase (proUK) was developed to make proUK less vulnerable to spontaneous activation in plasma. This was a problem that seriously compromised proUK in clinical trials, as it precluded proUK-mediated fibrinolysis at therapeutic concentrations. Methods and results: After completing dosefinding studies, 12 anesthetized dogs with femoral artery thrombosis were given either M5 (2.0 mg kg ) by i.v. infusion over 60 min (20% administered as a bolus). Two pairs of standardized injuries were inflicted at which hemostasis was completed prior to drug administration. Blood loss was quantified by measuring the hemoglobin in blood absorbed from these sites. Thrombolysis was evaluated at 90 min and was comparably effective by both activators. Rethrombosis developed in one t-PA dog. The principal difference found was that blood loss was 10-fold higher with t-PA (mean 40 mL) than with M5 (mean 4 mL) (P ¼ 0.026) and occurred at more multiple sites (mean 2.7 vs. 1.2). This effect was postulated to be related to differences in the mechanism of plasminogen activation by t-PA and M5 in which the latter is promoted by degraded rather than intact (hemostatic) fibrin. In addition, two-chain M5 was efficiently inactivated by plasma C1 inactivator, an exceptional property which helped contain its non-specific proteolytic effect. Conclusions: Intravascular thrombolysis by M5 was accompanied by significantly less bleeding from hemostatic sites than by t-PA. This was attributed to the proUK paradigm of fibrinolysis being retained at therapeutic concentrations by the mutation.

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An animal model of fibrinolytic bleeding based on the rebleed phenomenon: Application to a study of vulnerability of hemostatic plugs of different age

Cited by 22 publications

References 15 publications

Thrombolytic activity of BB-10153, a thrombin-activatable plasminogen

Thrombolytic activity of BB-10153, a thrombin-activatable plasminogen

Distinct dose-dependent effects of plasmin and TPA on coagulation and hemorrhage

Thrombolysis vs. bleeding from hemostatic sites by a prourokinase mutant compared with tissue plasminogen activator

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