The contemporary management of acute myocardial infarction

PEG-maleimide hydrogels for protein and cell delivery in regenerative medicine

Protein- and cell-based therapies represent highly promising strategies for regenerative medicine, immunotherapy, and oncology. However, these therapies are significantly limited by delivery considerations, particularly in terms of protein stability and dosing kinetics as well as cell survival, engraftment, and function. Hydrogels represent versatile and robust delivery vehicles for proteins and cells due to their high water content that retains protein biological activity, high cytocompatibility and minimal adverse host reactions, flexibility and tunability in terms of chemistry, structure, and polymerization format, ability to incorporate various biomolecules to convey biofunctionality, and opportunity for minimally invasive delivery as injectable carriers. This review highlights recent progress in the engineering of poly(ethylene glycol) hydrogels cross-linked using maleimide reactive groups for protein and cell delivery.

Dual delivery of hepatocyte and vascular endothelial growth factors via a protease-degradable hydrogel improves cardiac function in rats

Acute myocardial infarction (MI) caused by ischemia and reperfusion (IR) is the most common cause of cardiac dysfunction due to local cell death and a temporally regulated inflammatory response. Current therapeutics are limited by delivery vehicles that do not address spatial and temporal aspects of healing. The aim of this study was to engineer biotherapeutic delivery materials to harness endogenous cell repair to enhance myocardial repair and function. We have previously engineered poly(ethylene glycol) (PEG)-based hydrogels to present cell adhesive motifs and deliver VEGF to promote vascularization in vivo. In the current study, bioactive hydrogels with a protease-degradable crosslinker were loaded with hepatocyte and vascular endothelial growth factors (HGF and VEGF, respectively) and delivered to the infarcted myocardium of rats. Release of both growth factors was accelerated in the presence of collagenase due to hydrogel degradation. When delivered to the border zones following ischemia-reperfusion injury, there was no acute effect on cardiac function as measured by echocardiography. Over time there was a significant increase in angiogenesis, stem cell recruitment, and a decrease in fibrosis in the dual growth factor delivery group that was significant compared with single growth factor therapy. This led to an improvement in chronic function as measured by both invasive hemodynamics and echocardiography. These data demonstrate that dual growth factor release of HGF and VEGF from a bioactive hydrogel has the capacity to significantly improve cardiac remodeling and function following IR injury.

Plasma asymmetric dimethylarginine concentrations in newly diagnosed patients with acute myocardial infarction or unstable angina pectoris during two weeks of medical treatment

A high concentration of plasma asymmetric dimethylarginine (ADMA) has been associated with several risk factors for atherosclerosis, and this may increase the risk for acute coronary syndromes (ACSs). We measured plasma ADMA concentrations in patients who had newly diagnosed ACS (n = 48), and we followed the changes in ADMA concentrations during these patients' short-term medical therapy, which included various combination of drugs with or without percutaneous coronary interventions according to the needs of each patient. Concentrations of plasma ADMA were found to be high in patients who had ACS compared with 48 age-matched healthy control subjects (3.13 +/- 0.85 vs 1.57 +/- 0.85 mumol/L, p <0.0001). Follow-up measurements of ADMA showed dramatic decreases in plasma ADMA concentrations over 2 weeks of medical therapy for ACS (from 3.27 +/- 0.87 to 1.52 +/- 0.47 mumol/L, p <0.0001). Plasma ADMA at baseline showed a significant positive correlation with serum C-reactive protein and plasma insulin and a significant negative correlation with serum levels of high-density lipoprotein and plasma alpha-tocopherol. During therapy, changes in plasma ADMA concentrations were significantly correlated with changes in the ratio of total cholesterol to high-density lipoprotein cholesterol and in serum C-reactive protein concentrations but not with changes in insulin levels. This study provides the first evidence that plasma ADMA concentrations are significantly high in patients who have ACS and that ADMA concentrations rapidly decrease after short-term medical therapy.

Noncardiac applications of glycoprotein IIb/IIIa inhibitors

Platelet activation and aggregation have become increasingly recognized as the primary processes involved in the cascade that leads to thrombus formation in atherosclerotic vascular disease. Glycoprotein IIb/IIIa receptor inhibitors (GPI) favorably impact thrombus formation and distal embolization by inhibiting the final common pathway of platelet aggregation. Glycoprotein IIb/IIIa inhibitors have been used effectively in a wide variety of clinical scenarios including unstable angina, non-ST segment elevation myocardial infarction, ST segment elevation myocardial infarction, and low and high risk percutaneous coronary interventions with and without intracoronary stenting, however there is limited data regarding the use of these potent antiplatelet agents in the setting of extracardiac vascular disease. This article will review the non-cardiac applications of glycoprotein IIb/IIIa inhibitors in the setting of acute ischemic stroke, carotid and vertebral angioplasty and stenting, acute critical limb ischemia, and percutaneous interventions in peripheral arterial occlusive disease.