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Pharm Res. 2013 Jun;30(6):1663-76. doi: 10.1007/s11095-013-1011-x. Epub 2013 Mar 7.

Thrombus-targeted nanocarrier attenuates bleeding complications associated with conventional thrombolytic therapy.

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Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, 1300 Coulter St., Amarillo, Texas 79106, USA.



To test the hypothesis that thrombus-specific tissue plasminogen activator (tPA)-loaded nanocarriers enhance thrombolytic efficacy and attenuate hemorrhagic complications.


A series of pegylated and non-pegylated tPA-loaded liposomes were prepared and their surfaces were decorated with the peptide sequence (CQQHHLGGAKQAGDV) of fibrinogen gamma-chain that binds with GPIIb/IIIa expressed on activated platelets. All formulations were characterized for physical properties, stability and in vitro release profile. The thrombolytic activities of tPA-loaded liposomes were tested by visual end-point detection, fibrin agar-plate and human blood clot-lysis assays. The thrombus-specificity of the peptide-modified-liposomes was evaluated by studying the binding of fluorescent peptide-liposomes with activated platelets. The pharmacokinetic profile and thrombolytic efficacy were evaluated in healthy rats and an inferior vena-cava rat model of thrombosis, respectively.


Both pegylated and non-pegylated peptide-modified-liposomes showed favorable physical characteristics and colloidal stability. Formulations exhibited an initial burst release (40-50% in 30 min) followed by a continuous release of tPA (80-90% in 24 h) in vitro. Encapsulated tPA retained >90% fibrinolytic activity as compared to that of native tPA. Peptide-grafted-liposomes containing tPA demonstrated an affinity to bind with activated platelets. The half-life of tPA was extended from 7 to 103 and 141 min for non-pegylated and pegylated liposomes, respectively. Compared to native tPA, liposomal-tPA caused a 35% increase in clot-lysis, but produced a 4.3-fold less depletion of circulating fibrinogen.


tPA-loaded homing-peptide-grafted-liposomes demonstrate enhanced thrombolytic activity with reduced hemorrhagic risk.

[Indexed for MEDLINE]

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