Engineering nanoscale exosomes for targeted delivery of imaging and therapeutic reagents to hematopoietic stem cells

Z. Ehlinger, A. Beard, D. Levy, M.A. Do, B. Lu
Santa Clara University,
United States

Keywords: exosome, pesudotyping, hematopoietic stem cells


Targeted delivery of imaging and therpeutic reagents represents a transforming technology for basic research, pharmaceutical industry and translational medicine. Recently, nanoscale exosomes, the cell-derived extracellular vesicles, have attracted tremendous interests due to their intrinsic biocompatibility, large capacity, tissue-penetrating ability and programmability [1, 2]. However, engineering strategy must be invented before exosomes can be exploited to fulfill their role as a new generation of delivery vehicles. Very recently, we have developed a novel surface display technology to allow protein loading and cellular uptake using the molecular scaffold of glycoprotein from the vesicular stomach viral envelope (VSVG) [2]. VSVG can enhance cellular uptake of exosomes but in a non-discriminating manner, therefore limiting its application as a general delivery tool. To develop exosomes for targeted delivery, we elect to use a tissue-specific glycol-protein to replace VSVG for exosome modification. Here, we report the validation of a new glycoprotein (RD114A) for its ability to specifically targeting and modifying exosomes. By fusing it with the green fluorescent protein (GFP) imaging reporter, we first demonstrate that this new glycoprotein can preferentially integrate into exosome membranes, hence validating its use in exosome modification. We then show that modified exosomes can be produced indefinitely from genetically transformed cells. Last, we validate the proper modification of isolated exosomes and predicted cellular uptake by recipient cells. Because RD114A can specifically bind to CD34 antigen on the surface of hemopoietin stem cells, our study provides a pseudotyping strategy to engineer exosomes for targeted drug delivery in vitro and in vivo. Reference 1. Stickney Z, Losacco J, McDevitt S, Zhang Z, Lu B (2016) Development of exosome surface display technology in living human cells. Biochem Biophys Res Commun. 472(1):53-59 2. Meyer C, Losacco J, Stickney Z, Li L, Marriott G, Lu B (2017) Pseudotyping exosomes for enhanced protein delivery in mammalian cells. International Journal of Nanomedicine. 12:3153-3170