Lytic efficacy of apoli protein E2 (ApoE2) and recombinant tissue plasminogen activator (rt‐PA) treatment with 120 kHz ultrasound in an in‐vitro human clot model

Abstract Conditions were defined for the derivatization of recombinant tissue plasminogen activator (rt-PA) with polyethylene glycol (PEG) so as to retain functional activity as a possible means of producing a t-PA species with a prolonged circulating lifetime. Derivatives with a wide range of retention of activities were prepared by varying the concentration and species of activated PEG. The specific activities of the PEG-rt-PA derivatives were dependent on the method of assay. Assays using preformed fibrin gave higher estimates of retention of activity than assays using soluble components. Plasma elimination studies in mice and rats indicated prolonged circulating lifetimes for the radiolabeled PEG-rt-PA derivatives after a rapid clearance and distribution phase; however, the disappearance of functional activity was much more rapid than the disappearance of radiolabeled material. The PEG-rt-PA derivatives appeared to accumulate in tissues above their interstitial fluid concentrations and were rapidly inactivated, apparently by reaction with the plasma protease inhibitors. These results were consistent with the inactivation of the PEG-rt-PA derivatives in rat plasma in vitro. A somewhat longer half-life (t1/2) of the one derivative studied was observed in dogs (t1/2, 16 minutes) as compared with the rat (t1/2, five minutes). This was sufficient to confer thrombolytic activity upon the derivative (administered by bolus injection) in contrast to native rt-PA. The potential of PEG-modified rt-PA as a long-lived thrombolytic agent in humans will depend, however, on whether there will be a further extension of the t1/2 because of a reduction in clearance and/or a reduction in the rate of inactivation.

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Preparation of Peptide and Recombinant Tissue Plasminogen Activator Conjugated Poly(Lactic-Co-Glycolic Acid) (PLGA) Magnetic Nanoparticles for Dual Targeted Thrombolytic Therapy

International Journal of Molecular Sciences ◽

10.3390/ijms21082690 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2690 ◽

Cited By ~ 4

Author(s):

Huai-An Chen ◽

Yunn-Hwa Ma ◽

Tzu-Yuan Hsu ◽

Jyh-Ping Chen

Keyword(s):

Magnetic Nanoparticles ◽

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Glycolic Acid ◽

Blood Clot ◽

Recombinant Tissue Plasminogen Activator ◽

Clot Lysis ◽

High Dose ◽

Tissue Plasminogen

Recombinant tissue plasminogen activator (rtPA) is the only thrombolytic agent that has been approved by the FDA for treatment of ischemic stroke. However, a high dose intravenous infusion is required to maintain effective drug concentration, owing to the short half-life of the thrombolytic drug, whereas a momentous limitation is the risk of bleeding. We envision a dual targeted strategy for rtPA delivery will be feasible to minimize the required dose of rtPA for treatment. For this purpose, rtPA and fibrin-avid peptide were co-immobilized to poly(lactic-co-glycolic acid) (PLGA) magnetic nanoparticles (PMNP) to prepare peptide/rtPA conjugated PMNPs (pPMNP-rtPA). During preparation, PMNP was first surface modified with avidin, which could interact with biotin. This is followed by binding PMNP-avidin with biotin-PEG-rtPA (or biotin-PEG-peptide), which was prepared beforehand by binding rtPA (or peptide) to biotin-PEG-maleimide while using click chemistry between maleimide and the single –SH group in rtPA (or peptide). The physicochemical property characterization indicated the successful preparation of the magnetic nanoparticles with full retention of rtPA fibrinolysis activity, while biological response studies underlined the high biocompatibility of all magnetic nanoparticles from cytotoxicity and hemolysis assays in vitro. The magnetic guidance and fibrin binding effects were also confirmed, which led to a higher thrombolysis rate in vitro using PMNP-rtPA or pPMNP-rtPA when compared to free rtPA after static or dynamic incubation with blood clots. Using pressure-dependent clot lysis model in a flow system, dual targeted pPMNP-rtPA could reduce the clot lysis time for reperfusion by 40% when compared to free rtPA at the same drug dosage. From in vivo targeted thrombolysis in a rat embolic model, pPMNP-rtPA was used at 20% of free rtPA dosage to restore the iliac blood flow in vascular thrombus that was created by injecting a blood clot to the hind limb area.

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Erratum to ‘Effect of clot stiffness on recombinant tissue plasminogen activator lytic susceptibility in vitro’ [Ultrasound Med Biol 44 (2018) 2710-2727]

Ultrasound in Medicine & Biology ◽

10.1016/j.ultrasmedbio.2019.04.013 ◽

2019 ◽

Vol 45 (7) ◽

pp. 1860

Author(s):

Karla P. Mercado-Shekhar ◽

Robert Kleven ◽

Hermes Aponte Rivera ◽

Ryden Lewis ◽

Kunal B. Karani ◽

...

Keyword(s):

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Recombinant Tissue Plasminogen Activator ◽

Tissue Plasminogen

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Abstract 2589: Temperature Dependence of Lysis with Tissue Plasminogen Activator, Eptifibatide, and Ultrasound

Stroke ◽

10.1161/str.43.suppl_1.a2589 ◽

2012 ◽

Vol 43 (suppl_1) ◽

Author(s):

Jason M Meunier ◽

Brent Bluett ◽

Evan P Wenker ◽

Wan-Tsu W Chang ◽

George J Shaw

Keyword(s):

Combination Therapy ◽

Temperature Dependence ◽

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Recombinant Tissue Plasminogen Activator ◽

Fresh Frozen Plasma ◽

Water Tank ◽

Temperature Range ◽

Tissue Plasminogen

Introduction: Recombinant tissue plasminogen activator (rt-PA) is the only FDA approved thrombolytic therapy for acute ischemic stroke. Recent studies have shown hypothermia to be beneficial in patient outcome in stroke. However, rt-PA is less effective at temperatures less than 37°C. Interest in improving the lytic efficacy of rt-PA thrombolysis has led to the study of adjunctive therapies such as GP IIb-IIIa inhibitors like eptifibatide (Epf) and ultrasound (US) enhanced thrombolysis. However, the thrombolytic efficacy of combination therapy with rt-PA over a clinically applicable temperature range is unknown. Objective: The effects of temperature on the thrombolytic efficacy of combination rt-PA-driven thrombolysis were determined in an in-vitro human clot model. Methods: Human whole blood clots were made from blood obtained from volunteers, after local Institutional Review Board approval. Clots were made in 20-µL pipettes and placed in a water tank for microscopic visualization during treatment. Sample clots were exposed to human fresh-frozen plasma (hFFP) alone (Control); hFFP and rt-PA ([0.5 µg/ml]; “+rt-PA”); hFFP, rt-PA ([0.5 µg/ml]), and Epf ([0.63 µg/ml]; “+Epf”); and hFFP, rt-PA, Epf, and ultrasound supplied by a 2-MHz transcranial Doppler (TCD) unit (“+TCD”). Exposures were for 30 minutes at 30-37°C. Clot width was measured using a microscopic imaging technique and mean percent fractional clot loss (FCL) at 30 minutes was used to determine thrombolytic efficacy. Results: Each of 15 treatment groups had a minimum of 6 clots (range: 6-148) from 2 different donors (range: 2-21), for a total of 409 clots. At 37°C, FCLs for +rt-PA and +TCD groups were 44% (95% Confidence Interval: 37-52%) and 59% (54-64%) respectively (p<0.01). At 30°C, FCLs for +rt-PA and +TCD groups were 32% (27-36%) and 30% (26-33%) respectively (p not significant). Conclusion: Combination therapy using rt-PA, Epf, and 2-MHz US exhibits temperature dependence over a clinically applicable temperature range.

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