Stem cell-derived extracellular vesicles for myocardial infarction: a meta-analysis of controlled animal studies.

Stem cell-derived extracellular vesicles (EVs) have emerged as a promising therapy for myocardial infarction, but its effects remain incompletely understood. We aim to systematically review the efficacy of EVs on myocardial infarction in both small and large animals.On April 5, 2018, we searched the PubMed, Embase and Web of Science databases using variations of "myocardial infarction" and "extracellular vesicle". Controlled studies about the treatment effects of stem cell-derived EVs in myocardial infarction animal model were included. Meta-regression analysis was used to reveal the factors affecting the EVs treatments.Of 1210 studies retrieved, 24 were eligible for meta-analysis. EVs injection was associated with the improvements of left ventricular ejection fraction (12.65%), fractional shortening (7.54%) and the reduction of infarct size/area at risk (-15.55%). Meta-regression analysis did not reveal the association between treatment efficacy and type of stem cell, ligation-to-injection interval, route of delivery, dosage of delivery or follow-up period (all P values > 0.05). The median quality score of eligible studies was only 1, indicating potential risks of bias.Stem cell-derived EVs improve cardiac function and reduce infarct size in myocardial infarction animals, but current pool-up study reveals no associations between common factors and treatment effects.