Selective internalization of self-assembled artificial oil bodies byHER2/neu-positive cells

Abstract

A novel delivery carrier was developed using artificial oil bodies (AOBs). Plant seed oil bodies(OBs) consist of a triacylglycerol matrix surrounded by a monolayer of phospholipids embeddedwith the storage protein oleosin (Ole). Ole consists of a central hydrophobic domain withtwo amphiphatic arms that extrude from the surface of OBs. In this study, a bivalent anti-HER2/neu affibody domain (ZH2) was fused with Ole at the C terminus. After overproduction inEscherichia coli, the fusion protein (Ole-ZH2) was recovered to assemble AOBs. The size ofself-assembled AOBs was tailored by varying the oil/Ole-ZH2 ratio and pH toreach a nanoscale. Upon co-incubation with tumor cells, the nanoscale AOBsencapsulated with a hydrophobic fluorescence dye were selectively internalized byHER2/neu-overexpressing cells and displayed biocompatibility with the cells. In addition, theZH2-mediated endosomal entry of AOBs occurred in a time- and AOB dose-dependentmanner. The internalization efficiency was as high as 90%. The internalized AOBsdisintegrated at the non-permissive pH (e.g. in acidic endosomes) and the cargo dye wasreleased. Results of in vitro study revealed a sustained and prolonged release profile.Taken together, our findings indicate the potential of AOBs as a delivery carrier.