Use of tissue plasminogen activator in the emergency department for acute myocardial infarction

Potential clinical applications of exosomes in the diagnosis, treatment, and prognosis of cardiovascular diseases: a narrative review

Background and Objective

Cardiovascular diseases (CVDs) have been one of the most common threats to human health in recent decades. At present, despite many diagnostic, prognostic and therapeutic methods being applied in the clinic, the prevalence of CVDs continues to rise. Therefore, new discovery is needed and exosomes have received extensive attention. Exosomes are extracellular vesicles that enable communication between cells. They are widely distributed in biofluids, suggesting that they may be useful in CVD diagnosis and prognosis. Furthermore, exosomes are ideal drug transporters with relatively high transport efficiency and the capability to target different kinds of tissues. However, the present research concentrates, for the most part, on mechanistic studies with less attention to clinical applications.

Methods

More than 150 relevant scientific articles from databases like PubMed, Web of Science were screened and analysed for this narrative review. Data of clinical trials are collected from clinicaltrials.gov.

Key Content and Findings

In this review, we concentrate on different exosomes and CVDs, and we summarize the physiological and pathological roles of CVD-related exosomes. We focused on the role exosomes may have as biomarkers of CVDs, therapeutic opportunities, and possible hurdles to the clinical application of exosomes, aiming to provide a useful reference for its translational use in the CVD field.

Conclusions

Specific changes in exosome cargos (mainly miRNAs and proteins) are in accordance with the occurrence and development of CVDs including acute myocardial infarction (AMI), arrhythmia, coronary artery disease (CAD), heart failure (HF) and cardiomyopathy, therefore meaningful for diagnosis and prognosis of CVDs. For exosome related therapeutic methods, potential ways consist of direct administration of exosomes, targeting on exosome synthesis, processing and release, and working as adjuvants. All in all, exosomes are expected to serve as meaningful tools in the diagnosis, treatment and prognosis of CVDs.

Reperfusion injury of postischemic tissues

Reperfusion injury, occurring when blood circulation is restored to previously ischemic tissues, is now demonstrable as a pathophysiologic entity distinct from the primary ischemic injury that develops during ischemia per se. The primary pathogens that cause reperfusion injury are thought to be partially reduced oxygen species, including superoxide radicals, hydrogen peroxide, and hydroxyl radicals, which initiate lipid peroxidation and other deleterious oxidation reactions during the reperfusion period. Antioxidant drugs, given at the end of ischemia or at the very onset of reperfusion, can improve the postischemic function of isolated organs and the survival of intact animals subject to a cycle of circulatory arrest and reperfusion, suggesting that reperfusion injury is both a real and a preventable pathophysiologic entity.

Alteplase: a tissue plasminogen activator for acute myocardial infarction

Alteplase is a human tissue plasminogen activator (t-PA) produced by recombinant DNA technology. It is a relatively fibrin-specific thrombolytic agent, used primarily to lyse coronary artery clots. It has proven effective in the treatment of acute myocardial infarction (AMI). Despite continuous reevaluation of pharmacokinetic parameters for t-PA, limited distribution and clearance data mandate administration of t-PA as a continuous infusion. Tissue plasminogen activator is eliminated primarily by hepatic metabolism with an elimination half-life of five to ten minutes. Plasma levels show great interindividual variation but correlate with infusion rate and decrease in fibrinogen level. The current recommended dose is 100 mg administered as a 10-mg iv bolus followed by a continuous infusion over three hours. However, 40-150 mg has been used in clinical trials. The compound has undergone extensive testing, comparing it with placebo and streptokinase (SK), and combining it with angioplasty and coronary artery bypass surgery. Tissue plasminogen activator is effective at opening clotted coronary arteries in approximately 70 percent of AMI patients and has been shown to be approximately twice as effective as SK in one U.S. trial. Although there is considerable evidence of efficacy with t-PA, data evaluating the influence of t-PA on mortality are limited, but suggest a reduction to five percent. Currently, thrombolytic therapy is indicated for patients experiencing a transmural AMI with onset of symptoms within three to six hours before presenting to the emergency room. Active internal bleeding or conditions predisposing to serious hemorrhage are contraindications to thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

The FDA Advisory Panel's decision on rt-PA

Considerable dissatisfaction has been expressed over the FDA's Cardio-renal Advisory Panel's recommendation on May 29, 1987 that approval of rt-PA as a thrombolytic agent for the treatment of acute myocardial infarction be delayed. Justification for the Advisory Panel's action appears to be based on a lack of adequate data supporting the clinical benefit and safety of a specific therapeutic regimen of rt-PA, i.e., its molecular form, dosage, and duration of therapy. Although not an issue in the Panel's decision, questions can be raised concerning claims that rt-PA, in comparison to streptokinase, is a safer agent as far as bleeding complications are concerned, and is twice as effective in dissolving coronary thrombi during a period of potential clinical benefit. Also to be considered is the association of its use with a higher incidence of rethrombosis and a much greater cost.