Sun Wenqi, Xing Changyang, Zhao Lianbi, Zhao Ping, Yang Guodong, Yuan Lijun
Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, People's Republic of China; The State Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an 710032, People's Republic of China.
Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, People's Republic of China.
Mol Ther Nucleic Acids. 2020 Jun 5;20:558-567. doi: 10.1016/j.omtn.2020.03.016. Epub 2020 Apr 7.
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.
外泌体介导的核酸递送已成为一种很有前景的基因治疗策略。然而，由于其他组织对 外泌体的非特异性摄取所导致的内在脱靶效应仍然是临床应用的一大障碍。在本研究中，我们旨在通过同时封装由组织特异性微小RNA（miRNA）翻译激活的工程化信使核糖核酸（mRNA），并通过超声靶向微泡破坏（UTMD）提高靶向递送效率，来增强疗效并将脱靶效应降至最低。简而言之，对感兴趣转录本的上游进行工程改造，使其含有一个经两个miRNA识别位点修饰的内部核糖体进入位点（IRES）。体外报告基因实验表明，工程化mRNA可被封装到外泌体中，并能在受体细胞中被相应的miRNA翻译激活。通过一个原理验证性体内实验，我们将miR-148a（一种脂肪相对特异性的miRNA）响应性的过氧化物酶体增殖物激活受体γ共激活因子1α（PGC1α）mRNA封装到外泌体中，并借助UTMD将外泌体递送至脂肪组织。PGC1α在脂肪组织中被高效激活翻译，同时诱导明显的褐变。此外，PGC1α在肺和其他组织中的脱靶翻译要低得多。综上所述，我们的研究建立了一种新型的脂肪特异性外泌体递送策略，可同时提高疗效并将脱靶效应降至最低。
