MicroRNAs (miRNAs) effectively regulate gene expression in cultured cells and human disease models, and such regulation can be blocked with antibodies against miRNAs if miRNA-associated adverse effects occur. Promising findings using miRNAs to prevent disease progression in animal studies give hope to patients with disorders caused by dysregulated gene expression, such as cardiovascular diseases. Inflammatory cell infiltration, endothelial cell dysfunction, and angiogenesis are common pathologies of cardiovascular diseases. Accumulating data suggest that miRNA-mediated inhibition of gene expression can drive these pathologies in cardiac tissue or vasculature. It is often desirable to deliver exogenously prepared miRNAs or antibodies against miRNAs to target genes or miRNAs in specific cell or tissue types. Because naked miRNAs or antibodies against miRNAs are often unstable in the circulation, investigation has focused on their packaging and efficient delivery to diseased organs.