MicroRNAs<i> miR-1</i>,<i> miR-133a, miR-133b </i>and <i>miR-208</i> Are Dysregulated in Human Myocardial Infarction

<i>Objectives:</i> MicroRNAs (miRNAs) are noncoding single-stranded RNA molecules that regulate gene expression in physiological functions, development and disease. In recent studies, three miRNAs have been described as muscle or cardiac specific: <i>miR-1</i>, <i>miR-133</i>, and <i>miR-208</i>, being involved in heart development and disease; but there are limited data on their role in human myocardial infarction (MI). We therefore analyzed their expression in human MI. <i>Methods:</i> Autopsy samples of infarcted heart tissue from 50 patients with MI, 8 healthy trauma victims and 9 fetuses that died in utero were included. miRNAs <i>miR-1</i>, <i>miR-133a/b</i> and <i>miR-208</i> were analyzed using quantitative real-time polymerase chain reaction. <i>Results:</i><i>miR-208</i> was upregulated, whereas <i>miR-1</i> and <i>miR-133a </i>were downregulated in MI compared to healthy adult and fetal hearts. All four tested miRNAs were downregulated in fetal hearts compared to healthy adult hearts. <i>Conclusions:</i> Our study showed the involvement of muscle- and/or cardiac-specific miRNAs <i>miR-1, miR-133a</i>/<i>b</i> and <i>miR-208</i> in human MI. The most significant finding was upregulation of <i>miR-208</i> and downregulation of <i>miR-1</i> and <i>miR-133a </i>in MI compared to healthy adult hearts. Some patterns of miRNA expression were similar in MI and fetal hearts, supporting the concept of cardiac gene reprogramming in the remodeling of the heart.