טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentErtracht Offir
SubjectThe Cardioprotective Efficacy of TVP1022
DepartmentDepartment of Medicine
Supervisor Professor Emeritus Ofer Binah
Full Thesis textFull thesis text - English Version


Abstract

In cardiovascular diseases cardiomyocytes are exposed to hostile conditions. Consequently, cells die, through: necrosis, apoptosis or autophagy. A new treatment strategy, aimed at providing cardiomyocytes resistance to hostile environments, has emerged. This strategy relies on the effects of preconditioning and post-conditioning. Currently, research tries to mimic the "conditioning" effects pharmacologically.

TVP1022 is the s-enantiomer of the anti-parkinsonian FDA-approved drug - rasagiline. Unlike rasagiline, TVP1022 does not inhibit monoaminooxidases. Nevertheless, TVP1022 has an anti-apoptotic and cytoprotective efficacy in in-vitro and in-vivo models of neurodegenerative diseases. Therefore, we hypothesized that TVP1022 would have a cardioprotective efficacy in vivo. Accordingly, the aims of this dissertation were: A) to demonstrate the in-vivo cardioprotection efficacies of TVP1022 in models of myocardial damage; B) to investigate presumed mechanisms underlying the cardioprotection efficacies. TVP1022 was tested in two cardiac insults models: (A) Doxorubicin induced cardiotoxicity; (B) Left anterior descending artery ligation-induced myocardial infarction. In the doxorubicin model, TVP1022 was given as a pretreatment prior to the doxorubicin administration and continued after its conclusion. Cardiac function was evaluated using echocardiograph and Millar Mikro-Tip? catheter. Cardiac structural changes were assessed in histologic sections. Western blot was used to measure cardiac and apoptotic proteins' expression. In the myocardial infarction model, TVP1022 was given: (A) Premyocardial infarction, (B) Post myocardial infarction, (C) Before reperfusion period. The main parameter measured was the infarct size, measured using the triphenyltetrazolium chloride staining method. Additionaly, in the ischemia/reperfusion model cardiac function was evaluated by echocardiography and mitochondrial membrane integrity was estimated by exposing isolated mitochondria to a Ca2 challenge.

TVP1022 had beneficial effects against both insults: (1) TVP1022 prevented doxorubicin-induced rats' behavioral changes; (2) TVP1022 preserved rats' weight and cardiac function; (4) TVP1022 preserved hemodynamic parameters; (5) TVP1022 treatment didn’t affect cardiac structure or protein expression; (6) TVP1022 reduced infarct size when given as a pre-myocardial infarction treatment, or before reperfusion; (7) TVP1022 didn’t affect infarct size when given after myocardial infarction; (8) In the ischemia/reperfusion model TVP1022 treatment preserved cardiac function and mitochondrial membrane integrity. We use in-vitro experiments to decipher the TVP1022 mechanism of action, We found that TVP1022 activates two signaling pathways: PKC and PI3K/Akt/GSK-3β. Specifically, TVP1022 facilitates the phosphorylation of two regulatory proteins, PI3K and PKCε. This is followed by the activation of GSK-3β which closes the mitochondrial permeability transition pore and increase expression of antiapoptotic protein Bcl-2. These conditions, probably, make the cardiomyocytes resilient to the cardiovascular disease-induced hostile conditions.