Accelerated thrombolysis in a rabbit model of carotid artery thrombosis with liposome-encapsulated and microencapsulated streptokinase

Summary

The present study compares the efficacy of two formulations of encapsulated streptokinase to streptokinase in a rabbit model of carotid artery thrombosis. Arterial thrombosis followed the injection of thrombin mixed with autologous whole blood into a carotid artery of New Zealand white rabbits. Thirty minutes after the confirmation of an occlusive thrombus, one of four streptokinase formulations was infused at a dosage of 6,000 IU/kg into the jugular vein. Free streptokinase (FREE SK) was compared to identical dosages of streptokinase encapsulated in a liposome (LESK), streptokinase entrapped in a water-soluble polymer (MESK), and free streptokinase admixed with blank microparticles (FREE SK + BLANK). Carotid arterial blood flow was determined by pulsed Doppler flowmetry to confirm clot formation and reperfusion. Two hours after drug infusion, the rabbits were killed and the residual thrombus mass was determined.

Compared to FREE SK (74.5 ± 16.9 min; mean ± SEM), LESK demonstrated significantly reduced reperfusion times (19.3 ± 4.6 min) while MESK exhibited even greater improvement (7.3 ± 1.6 min). FREE SK + BLANK showed no statistical improvement versus FREE SK. LESK and MESK also resulted in reduced residual clot mass and greater return of arterial blood flow. These studies suggest that encapsulation of streptokinase offers a potential method of improved fibrinolytic treatment for patients with clot-based disorders. MESK performed slightly better than LESK with improved production and storage characteristics.

Keywords

Thrombolytic therapy - streptokinase - microencapsulation - liposomes - thrombus

• References

• 1 American Heart Association. Heart Disease and Stroke Statistics – 2003 Update. Dallas, Texas; American Heart Association: 2002
• 2 The National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. N Engl J Med 1995; 333: 1581-7.
• 3 The Multicenter Acute Stroke Trial — Europe Study Group. Thrombolytic therapy with streptokinase in acute ischemic stroke. N Engl J Med 1996; 335: 145-50.
• 4 Francis CW, Marder VJ. Mechanisms of fibrinolysis. In: Hematology. Williams, Beutler, Erslev, Lichtman, eds; McGraw-Hill: 1983: 1266-76.
• 5 Juhlin P, Bostrom PA, Torp A. et al. Streptokinase antibodies inhibit reperfusion during thrombolytic therapy with streptokinase in acute myocardial infarction. J Intern Med 1999; 245: 483-8.
• 6 Tuliani VV, O’Rear EA. Circulatory concentrations of fibrinolytic species during thrombolytic therapy estimated by stirred-tank reactor analysis. Pharm Res 1997; 14: 1051-7.
• 7 Nguyen PD, O’Rear EA, Johnson AE. et al. Thrombolysis using liposomal-encapsulated streptokinase: an in vitro study. Proc Soc Expt Biol Med 1989; 192: 261-9.
• 8 Nguyen PD, O’Rear EA, Johnson AE. et al. Accelerated thrombolysis and reperfusion in a canine model of myocardial infarction by liposomal encapsulation of streptokinase. Circ Res 1990; 66: 875-8.
• 9 Li ZL, Zhang NZ, Nie YH. Accelerated thrombolysis by liposomal-encapsulated urokinase in a canine model of acute myocardial infarction. Chung Hua I Hsueh Tsa Chih 1994; 74: 338-40.
• 10 Heeremans JLM, Prevost R, Bekkers MEA. et al. Thrombolytic treatment with tissue-type plasminogen activator (t-PA) containing liposomes in rabbits: a comparison with free t-PA. Thromb Haemost 1995; 73: 488-94.
• 11 Perkins WR, Vaughan DE, Plavin SR. et al. Streptokinase entrapment in interdigitation-fusion liposomes improves thrombolysis in an experimental rabbit model. Thromb Haemost 1997; 77: 1174-8.
• 12 Watts PJ, Davies MC, Mella CD. Microencapsulation using emulsification/solvent evaporation: An overview of techniques and applications. Crit Rev Ther Drug Carrier Syst 1990; 3: 235-59.
• 13 Harris JM. Introduction to biotechnical and biomedical applications of poly(ethylene glycol). In: Poly(ethylene glycol) chemistry: Biotechnical and Biomedical Applications. Harris, ed; Plenum Press: 1992: 1-14.
• 14 Jameela SR, Misra A, Jayakrishnan A. Cross-linked chitosan microspheres as carriers for prolonged delivery of macromolecular drugs. J Biomater Sci Polym Ed 1994; 6: 621-32.
• 15 Jayakrishnan A, Jameela SR. Glutaraldehyde as a fixative in bioprostheses and drug delivery matrices. Biomaterials 1996; 17: 471-84.
• 16 Oner L, Groves MJ. Properties of human albumin microparticles prepared by a chilled cross-linking technique. J Pharm Pharmacol 1993; 45: 866-70.
• 17 Jackson KW, Esmon N, Tang J. Streptokinase and staphylokinase. Methods Enzymol 1981; 80: 387-94.
• 18 Jeynes BJ. Treatment of experimentally induced cerebral atherothromboembolism in an animal model with streptokinase and taurochenodeoxycholate. Artery 1988; 15: 259-71.
• 19 Haglund AC, Ronquist G, Frithz G. et al. Alteration of the fibrinogen molecule and its phosphorylation state in myocardial infarction patients undergoing thrombolytic treatment. Thromb Res 2000; 98: 147-56.
• 20 Collen D. Thrombolytic therapy. Thromb Haemost 1997; 78: 742-6.
• 21 Reimer KA, Lowe JE, Rasmussen MM. et al. The wavefront phenomenon of ischemic cell death. I. Myocardial infarct size vs. duration of coronary occlusion in dogs. Circulation 1977; 56: 786-94.
• 22 Liem AL, van’t Hof AWJ, Hoorntje JCA. et al. Influence of treatment delay on infarct size and clinical outcome in patients with acute myocardial infarction treated with primary angioplasty. J Am Coll Cardiol 1998; 32: 629-33.
• 23 Heeremans JLM, Prevost R, Feltsma H. et al. Clot accumulation characteristics of plasmino-gen-bearing liposomes in a flow-system. Thromb Haemost 1998; 79: 144-9.
• 24 Juliano RL. Factors affecting the clearance kinetics and tissue distribution of liposomes, microspheres, and emulsions. Adv Drug Deliv Rev 1988; 2: 31-54.
• 25 Semple SC, Chonn A, Cullis PR. Interactions of liposomes and lipid-based carrier systems with blood proteins: Relation to clearance behaviour in vivo. Adv Drug Deliv Rev 1998; 32: 3-17.
• 26 Zalipsky S, Lee C. Use of functionalized poly(ethylene glycol)s for modification of polypeptides. In: Poly(ethylene glycol) chemistry: Biotechnical and Biomedical Applications. Harris, ed: Plenum Press 1992: 347-370.
• 27 Heeremans JLM, Gerritsen HR, Meusen SP. et al. The preparation of tissue-type plasmino-gen activator (t-PA) containing liposomes: Entrapment efficiency and ultracentrifugation damage. J Drug Target 1995; 3: 301-10.
• 28 Heeremans JLM, Mijnheer FW, Gerritsen HR. et al. Long-term stability of liposomes containing both tissue-type plasminogen activator and glu-plasminogen. Int J Pharm 1996; 129: 191-202.