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Tesi etd-09202019-103906

Type of thesis
Perfezionamento
Author
COLASUONNO, MARIANNA
URN
etd-09202019-103906
Title
Novel nanobased therapeutic approaches for thrombolysis
Structure
MED/11
Course
SCIENZE MEDICHE - Translational Medicine
Committee
Membro Prof. EMDIN, MICHELE
Membro Prof. RECCHIA, FABIO ANASTASIO
Membro Prof.ssa ANGELONI, DEBORA
Keywords
  • nanoparticles
  • thrombolysis
  • shape
  • deformability
  • dynamic dissolution
Exam session start date
;
Availability
completa
Abstract
A thrombus, or blood clot, is the final product of the blood coagulation step in hemostasis. It is a healthy response to injury intended to prevent bleeding, but can be harmful in thrombosis, when clots obstruct blood flow through healthy blood vessels. A plethora of risk factors and pathologic conditions can lead to blood clot formation. The obstruction of the blood flow due to the presence of a thrombus in the arterial vessels can induce myocardial infarctions, ischemic strokes or trigger peripheral arterial diseases; whereas obstructions on the venous side can lead to deep vein thrombosis and pulmonary embolism. <br>Tissue plasminogen activator (tPA) is the sole approved therapeutic molecule for the treatment of acute ischemic stroke. Yet, only a small percentage of patients could benefit from this life-saving treatment because of medical contraindications and severe side effects, including brain hemorrhage, associated with delayed administration.<br>To overcome these side effects and enhance drug therapeutic efficacy, the reformulation of thrombolytic molecules into nanotechnological platforms is proposed here. A nano therapeutic agent is realized by directly associating the clinical formulation of tPA to the porous structure of soft discoidal polymeric nanoconstructs (tPA-DPNs). The porous matrix of DPNs protects tPA from rapid degradation, allowing tPA-DPNs to preserve over 70% of the tPA original activity after 3 h of exposure to serum proteins. Under dynamic conditions, tPA-DPNs dissolve clots more efficiently than free tPA, as demonstrated in a microfluidic chip where clots are formed mimicking in vivo conditions. At 60 min post treatment initiation, the clot area reduces by half (57 + 8%) with tPA-DPNs, whereas a similar result (56 + 21%) is obtained only after 90 min for free tPA. In murine mesentery venules, the intravenous administration of 2.5 mg/kg of tPA-DPNs resolves almost 90% of the blood clots, whereas a similar dose of free tPA successfully recanalize only about 40% of the treated vessels. At about 1/10 of the clinical dose (1.0 mg/kg), tPA-DPNs still effectively dissolve 70% of the clots, whereas free tPA works efficiently only on 16% of the vessels. In vivo, discoidal tPA-DPNs outperform the lytic activity of 200 nm spherical tPA-coated nanoconstructs in terms of both percentage of successful recanalization events and clot area reduction. The conjugation of tPA with preserved lytic activity, the deformability and blood circulating time of DPNs, together with the faster blood clot dissolution, make tPA-DPNs a promising nanotool for enhancing both potency and safety of thrombolytic therapies.
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