There are at least 50 lysosomal storage diseases that are caused by accumulation of a substrate due to a defective enzyme. Although some treatment options are available, low efficacy, high cost, and immunogenicity are main challenges of current treatments. To overcome those limitations, we use cell-derived nanoparticles to deliver biologically active cargos into lysosomes. Naturally produced exosomes can deliver proteins without triggering an immune response. Additionally, exosome have an intrinsic ability to cross blood brain barrier benefiting patients at a late disease stage that affects the brain. After fusing either Gaussia luciferase (gLuc) or puromycin resistant protein (puro) onto a vesicular stomatitis virus glycoprotein (VSVG) with GFP/RFP reporters, we show that exosomes can be loaded with the recombinant protein without changing basic characteristics of exosomes. Moreover, we show that the biological activity of the proteins is retained in both the producer and recipient cells at a statistically significant level. As expected, the modified exosomes co-localize with both lysosomal and endosomal compartments indicating that they still undergo an endosomal pathway after an uptake assay. This work demonstrates that we can engineer nanoscale exosomes for delivery of therapeutic enzymes into lysosomes. The engineered vesicles have a great potential of becoming a method for enzyme delivery into patients with a lysosomal storage disease
