Exosome-Mediated Mitochondrial Delivery of Antisense Oligonucleotides.

We present a general method for in-cellulo delivery of 2'-O-methyl (2'-OMe) RNA oligonucleotides (oligos) to mitochondria for antisense applications, with potential for implementation in other mitochondrial DNA (mtDNA)-targeted therapies. Exosomes, which are nanoscale, naturally occurring extracellular vesicles (EVs), have been employed for biotechnology applications in oligonucleotide delivery in recent years. We discovered that exosomes from fetal bovine serum (FBS) can be used as a simple and biologically compatible delivery agent of 2'-OMe RNA antisense oligonucleotides to cellular mitochondria, leading to target protein knockdown. While most RNA interference and antisense mechanisms occur in the cytoplasm or nucleus, the need for mitochondrial targeting has become increasingly apparent. Mitochondrial disease describes a variety of currently incurable syndromes that especially affect organs requiring significant energy including the muscles, heart, and brain. Many of these syndromes result from mutations in mtDNA, which codes for the 13 proteins of the oxidative phosphorylation system and are thus often implicated in inherited metabolic disorders.