Abstract 2167: Efficient and rapid cellular delivery of bioactive proteins using EXPLOR: exosomes engineered for protein loading via optically reversible protein-protein interaction
Authors: Yim Nambin , Ryu Seung-Wook , Choi Kyungsun , Lee Kwang Ryeol , Lee Seunghee , Choi Hojun , Park Jiho , Kim Daesoo , Heo Wondo , Choi Chulhee 
Published: July 2016

Abstract
Despite the long list of therapeutic proteins available for treating various human diseases, the vast majority of commercial protein-based drugs, such as cytokines, hormones, and monoclonal antibodies, have been limited to extracellular mechanisms of action. Many intracellular proteins with great potential as biopharmaceutical drugs have been identified; however, many of the challenges associated with intracellular protein delivery have yet to be solved. Although protein transduction and lipid nanoparticle-mediated protein delivery methods have been proposed for direct protein delivery into target cells and tissues, many obstacles remain before these methods can be successfully employed in vivo, including low purification efficiency, failure to separate from nanoparticles in recipient cells, and induction of immune responses against host immune cells. To address these limitations, we developed an opto-genetically engineered exosome system, named ‘exosomes for protein loading via optically reversible protein-protein interaction” (EXPLOR) that can deliver soluble proteins into the cytosol via controlled, reversible protein-protein interactions (PPI). Among nanoparticles, cell-derived exosomes have recently been highlighted as new therapeutic strategies for the in vivo delivery of nucleotides and chemical drugs. Exosomes are natural cell-derived extracellular vesicles that originate from internal endocytic compartments and multi-vesicular bodies and participate in intercellular communication. Recent studies have sought to use exosomes as a new method for the in vivo delivery of siRNA or miRNA to specific target tissues by systemic injection. These methods were based on the passive loading of siRNAs or miRNAs into isolated exosomes by electrophoresis, a method poorly suited for the intracellular delivery of cellular proteins. By integrating a reversible PPI module controlled by blue light with the endogenous process of exosome biogenesis, we were able to successfully load cargo proteins into newly generated exosomes. Treatment with protein-loaded EXPLORs was shown to significantly increase intracellular levels of cargo proteins and their function in recipient cells in both a time- and dose-dependent manner. In the present study, we have demonstrated the intracellular delivery of mCherry, Cre enzyme, Bax, and Super repressor IκB proteins as functional proteins in the target cells and in vivo. These results clearly indicate the potential of EXPLORs as a mechanism for the efficient intracellular transfer of protein-based drugs into recipient cells and tissues both in vitro and in vivo.
Citation Format: Nambin Yim, Seung-Wook Ryu, Kyungsun Choi, Kwang Ryeol Lee, Seunghee Lee, Hojun Choi, Jiho Park, Daesoo Kim, Wondo Heo, Chulhee Choi. Efficient and rapid cellular delivery of bioactive proteins using EXPLOR: exosomes engineered for protein loading via optically reversible protein-protein interaction. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2167.