Ultrasound Assisted Exosomal Delivery of Tissue Responsive mRNA for Enhanced Efficacy and Minimized Off-Target Effects

• Published in: Molecular therapy. Nucleic acids 2020-06, Vol.20, p.558-567
• Main Authors: Sun, Wenqi, Xing, Changyang, Zhao, Lianbi, Zhao, Ping, Yang, Guodong, Yuan, Lijun
• Format: Article
• Language: English
• Subjects: browning; efficacy; exosomes; gene therapy; internal ribosomal entry site; obesity; off-target effects; tissue specific translational activation; ultrasound targeted microbubble destruction
• ISSN: 2162-2531; 2162-2531
• DOI: 10.1016/j.omtn.2020.03.016

Exosome-mediated nucleic acids delivery has been emerging as a promising strategy for gene therapy. However, the intrinsic off-target effects due to non-specific uptake of exosomes by other tissues remain the big hurdle for clinical application. In this study, we aimed to enhance the efficacy and minimize the off-target effects by simultaneously encapsulating engineered mRNA translationally activated by tissue-specific microRNA (miRNA) and increasing targeted delivery efficiency via ultrasound-targeted microbubble destruction (UTMD). Briefly, the upstream of interest transcript was engineered to harbor an internal ribosome entry site (IRES) modified with two miRNA recognition sites. In vitro reporter experiments revealed that the engineered mRNA could be encapsulated into exosomes and can be translationally activated by corresponding miRNAs in the recipient cells. By a proof-of-principle in vivo experiment, we encapsulated miR-148a (an adipose relatively specific miRNA)-responsive PGC1α mRNA into exosomes and delivered the exosomes into the adipose tissue with the aid of UTMD. Efficient PGC1α translation was activated in the adipose tissue, together with obvious browning induction. Moreover, there was much lower off-target translation of PGC1 α in lungs and other tissues. Taken together, our study establishes a novel adipose-specific exosome delivery strategy to enhance efficacy and minimize off-target effects simultaneously. [Display omitted] Intrinsic off-target effects emerge as an obstacle to exosome-mediated nucleic acid delivery. In this proof-of-concept study, an adipose tissue-responsive PGC1α mRNA was encapsulated into exosomes and delivered into adipose tissue with the aid of ultrasound-targeted microbubble destruction. The novel strategy enhanced delivery efficacy and minimized off-target effects.