Reduction of canine infarct size by bolus intravenous administration of liposomal prostaglandin E1: comparison with control, placebo liposomes, and continuous intravenous infusion of prostaglandin E1

The role of anti-inflammatory drugs and nanoparticle-based drug delivery models in the management of ischemia-induced heart failure

Ongoing advancements in the treatment of acute myocardial infarction (MI) have significantly decreased MI related mortality. Consequently, the number of patients experiencing post-MI heart failure (HF) has continued to rise. Infarction size and the extent of left ventricular (LV) remodeling are largely determined by the extent of ischemia at the time of myocardial injury. In the setting of MI or acute phase of post-MI LV remodeling, anti-inflammatory drugs including intravenous immunoglobulin (IVIG) and Pentoxifylline have shown potential efficacy in preventing post-MI remodeling in-vitro and in some clinical trials. However, systemic administration of anti-inflammatory drugs are not without their off-target side effects. Herein, we explore the clinical feasibility of targeted myocardial delivery of anti-inflammatory drugs via biodegradable polymers, liposomes, hydrogels, and nano-particle based drug delivery models (NDDM) based on existing pre-clinical and clinical models. We summarize the barriers to clinical application of targeted anti-inflammatory delivery post-MI, including challenges in achieving sufficient retention and distribution, as well as the potential need for multiple dosing. Collectively, we suggest that localized delivery of anti-inflammatory agents to the myocardium using NDDM is a promising approach for successful treatment of ischemic HF. Future studies will be instrumental in determining the most effective target and delivery modalities for orchestrating NDDM-mediated treatment of HF.

The interstitium in cardiac repair: role of the immune-stromal cell interplay

Cardiac regeneration, that is, restoration of the original structure and function in a damaged heart, differs from tissue repair, in which collagen deposition and scar formation often lead to functional impairment. In both scenarios, the early-onset inflammatory response is essential to clear damaged cardiac cells and initiate organ repair, but the quality and extent of the immune response vary. Immune cells embedded in the damaged heart tissue sense and modulate inflammation through a dynamic interplay with stromal cells in the cardiac interstitium, which either leads to recapitulation of cardiac morphology by rebuilding functional scaffolds to support muscle regrowth in regenerative organisms or fails to resolve the inflammatory response and produces fibrotic scar tissue in adult mammals. Current investigation into the mechanistic basis of homeostasis and restoration of cardiac function has increasingly shifted focus away from stem cell-mediated cardiac repair towards a dynamic interplay of cells composing the less-studied interstitial compartment of the heart, offering unexpected insights into the immunoregulatory functions of cardiac interstitial components and the complex network of cell interactions that must be considered for clinical intervention in heart diseases.

Micro- and Nanoparticles for Treating Cardiovascular Disease

Cardiovascular disease, including myocardial infarction (MI) and peripheral artery disease (PAD), afflicts millions of people in Unites States. Current therapies are insufficient to restore blood flow and repair the injured heart or skeletal muscle, respectively, which is subjected to ischemic damage following vessel occlusion. Micro- and nano-particles are being designed as delivery vehicles for growth factors, enzymes and/or small molecules to provide a sustained therapeutic stimulus at the injured tissue. Depending on the formulation, the particles can be injected directly into the heart or skeletal muscle, or accumulate at the site of injury following an intravenous injection. In this article we review existing particle based therapies for treating MI and PAD.

Passive targeting of lipid-based nanoparticles to mouse cardiac ischemia-reperfusion injury

Reperfusion therapy is commonly applied after a myocardial infarction. Reperfusion, however, causes secondary damage. An emerging approach for treatment of ischemia-reperfusion (IR) injury involves the delivery of therapeutic nanoparticles to the myocardium to promote cell survival and constructively influence scar formation and myocardial remodeling. The aim of this study was to provide detailed understanding of the in vivo accumulation and distribution kinetics of lipid-based nanoparticles (micelles and liposomes) in a mouse model of acute and chronic IR injury. Both micelles and liposomes contained paramagnetic and fluorescent lipids and could therefore be visualized with magnetic resonance imaging (MRI) and confocal laser scanning microscopy (CLSM). In acute IR injury both types of nanoparticles accumulated massively and specifically in the infarcted myocardium as revealed by MRI and CLSM. Micelles displayed faster accumulation kinetics, probably owing to their smaller size. Liposomes occasionally co-localized with vessels and inflammatory cells. In chronic IR injury only minor accumulation of micelles was observed with MRI. Nevertheless, CLSM revealed specific accumulation of both micelles and liposomes in the infarct area 3 h after administration. Owing to their specific accumulation in the infarcted myocardium, lipid-based micelles and liposomes are promising vehicles for (visualization of) drug delivery in myocardial infarction.

The effect of primary percutaneous coronary intervention as compared to tenecteplase on myeloperoxidase, pregnancy-associated plasma protein A, soluble fibrin and D-dimer in acute myocardial infarction

INTRODUCTION

Acute coronary reperfusion is accomplished pharmacologically with intravenous thrombolytic therapy or mechanically with primary percutaneous coronary intervention (PCI).

METHODS

We have determined the immediate effects of the main coronary reperfusion procedures on the plasma concentrations of myeloperoxidase (MPO), pregnancy-associated plasma protein A (PAPP-A), fibrin monomer (FM) and D-dimer (DD). We studied a total of 38 patients admitted for ST-segment elevation infarct (STEMI). 18 patients were given thrombolytic therapy with tenecteplase and 20 were treated with primary PCI.

RESULTS

The plasma concentrations of PAPP-A increased by a factor of six to eight times (p<0.001) following both reperfusion therapies. No significant increase was observed for MPO by either procedure. DD and FM concentrations both increased significantly following thrombolytic therapy, p=0.000, whereas only minor increases, although statistically significant for FM (p=0.013), were noted after PCI. DD and FM were highly correlated prior to the two treatment regimens (R=0.91), and were still highly correlated after PCI (R=0.94) and thrombolytic therapy (R=0.86). No correlation was demonstrated between PAPP-A and markers of activated coagulation.

CONCLUSIONS

This is the first report of a significant rise in the plasma concentration of PAPP-A after PCI as compared to thrombolytic treatment (p=0.002) and may indicate a greater impact of PCI than that of thrombolytic therapy on target coronary plaques.

Effect of prostaglandin E1 on ischemia-reperfusion injury during abdominal aortic aneurysm surgery

OBJECTIVE

Abdominal aortic aneurysm (AAA) surgery subjects the lower extremities to ischemia and reperfusion. Although it is not extensive or prolonged, ischemia of the lower extremities during aortic cross-clamping is gradually and steadily induced. We studied the effects of prostaglandin E1 (PGE1) on ischemia-reperfusion injury of the lower extremities during AAA repair.

METHODS

During AAA surgery, two near-infrared spectroscopy probes were positioned on each calf muscle to monitor oxygen metabolism in the lower extremities. We also measured lactate concentration in both iliac veins.

RESULTS

Near-infrared spectroscopy signals responded sensitively to aortic cross-clamping and declamping. Lactate increased time-dependently during aortic cross-clamping. The continuous venous administration of PGE1 (20 ng/kg per minute) inhibited the accumulation of lactate during aortic cross-clamping. Declamping of the first iliac artery resulted in a further but transient increase in ipsilateral venous lactate, which may be one component in the mechanism of declamping shock. Prostaglandin E1 eliminated the transient increase in ipsilateral lactate. The administration of PGE1 inhibited the contralateral accumulation of lactate after first declamping, and the lactate level decreased gradually before the second declamping.

CONCLUSIONS

Prostaglandin E1 seems to have a protective effect against ischemia-reperfusion injury of the lower extremities during AAA surgery.