Intrapericardial Delivery of PLGA-PGI2 Nanoparticles in an Acute Ischemia and Reperfusion Porcine Model

Cardiovascular disease is the most common cause of death in the United States and Europe, accounting for 840,678 and 4.1 million deaths annually, respectively. In the case of Myocardial Infarction, occlusion of a major blood vessel serving the heart occurs, usually due to development of a clot. Current therapies to treat MI include medications or surgery with the ultimate goal of restoring of blood flow. These strategies do not address the prevention of future coronary events and may cause ischemia/reperfusion injury, which contributes to an increase in infarct size. Patients who survive a MI exhibit an increased secretion of HGF from the infarct area which can be related to improved cardiac function. Use of HGF as a direct therapeutic agent is limited by its high molecular weight, half-life of approximately 4 minutes, and its low capability to penetrate into and be absorbed by the myocardium. This thesis proposes a prostaglandins sustained delivery to stimulate the production of endogenous myocardial HGF and generate pro-angiogenic, anti-apoptotic, anti-inflammatory and anti-fibrotic effects. Remodulin is a FDA-approved small molecule drug that mimics the actions of the prostacyclin PGI2 as a vasodilator with anti-platelet aggregation properties. Because of coronary washout, only a small fraction of the therapeutic agents reach and remain in the heart for a sufficient period of time. An IPC delivery system is proposed for local and sustained drug delivery to the entire heart, to avoid off-target side effects caused by excessive dosing and systemic blood circulation. A non-invasive surgical approach to access the pericardium is envisioned to remove the complications of an open chest procedure. Therapeutic delivery is achieved by injecting into the pericardial space PLGA NPs encapsulated with Remodulin or unformulated drug. An in vitro study was completed to study the modulating effect of Remodulin (PGI2 analog) on the HGF/c-Met signaling pathway in primary HCF-V using RT-qPCR.Remodulin encapsulation is characterized with UPCL-PDA. An in vivo experiment of a porcine model was performed inducing MI by the LAD artery occlusion and infusing the treatment. Coronary sinus and systemic blood, and pericardial fluid were collected and after euthanasia, tissue samples were taken from heart to study pharmacokinetics and the amount of drug present, quantified using LC-MS/MS. LV analysis was performed using ventriculograms taken during the procedure to calculate stroke volume and ejection fraction in order to observe improvements of LV performance after IPC treatment and an increase in EF% was observed. The in vitro test of unformulated drug demonstrated an up-regulation of HGF, c-Met and SDC1 in HCF-V cells. In vivo experiment was successful in establishing I/R injury , confirmed by increased blood levels of troponin and CK. The analysis of the blood after the In vivo experiment revealed low level of drug in systemic blood circulation contrary to the level observed in pericardial fluid. Coupling the delivery route with nano-formulated drug would provide prolonged and sustained effects, which would be extremely beneficial to patients permanently suffering from decreased coronary blood flow with limited therapeutic options. Further investigations will be aimed to optimize the therapeutic range of the delivered drug, limiting possible off-target side effects and allowing faster patients recovery after MI and preventing future heart failure.