Protein transduction into the mouse otocyst using arginine-rich cell-penetrating peptides

The mouse otocyst, an anlage of the inner ear, is an attractive experimental target for developing treatment modalities for congenital inner ear diseases and for studying inner ear development. Poly-arginine (6-12 residues) is a cell-penetrating peptide and can be used to deliver cargo into cells. Here, we achieved transutero delivery of enhanced green fluorescent protein (EGFP) fused to a nine-arginine peptide into mouse embryonic otocysts. The EGFP signal was detected both in the lining cells of the otocysts and in their vicinity at 18 h post injection. Mice injected with EGFP fused to a nine-arginine peptide had normal auditory and vestibular functions. These data suggest that protein transduction using poly-arginine may be a useful alternative strategy to commonly used gene delivery methods for delivering therapeutically relevant molecules to the developing inner ear.