Abstract
Reversing pathologic alterations in vascular microRNA (miRNA) expression represents a potential therapeutic strategy for pulmonary hypertension. While polyethylenimine (PEI) has previously been shown to be an effective vehicle for vascular lung-directed delivery of plasmid DNA, it remains unclear whether this utility is generalizable to miRNAs. Here we show that despite elevated lung levels, the intravenous infusion of PEI-miRNA mimic complexes fails to provide lung-selective delivery in rats.