Systemic delivery of MicroRNA mimics with polyethylenimine elevates pulmonary microRNA levels, but lacks pulmonary selectivity

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.