Brain targeting Results：
To produce the exosomes that have RVG on their surface for brain targeting, we first transfected the exosome-producing cells, HEK 293T cells, with the plasmid encoding the fusion protein of lamp 2b and RVG peptide.
To check if the RVG-containing exosomes can target brain, we use a siRNA as probe. We first encapsulated the siRNA into the RVG-modified exosomes by direct transfection of the HEK 293T cells with siRNA probe.

1.Quantification of siRNA contained in the exosomes
We first quantify the amount of siRNA encapsulated into the exosomes. We transfected the HEK 293T cells (transfected with RVG plasmids before) with siRNA before collecting the exosome. We used the exosomes collected from the HEK 293T cells (transfected with RVG plasmids before) without transfection of siRNA as negative control.
By quantitative PCR analysis of a series of siRNA with known concentration, we drew a standard curve. By referring to this curve, we calculate the absolute amount of siRNA in the exosomes. As shown in Fig.1, the amount of siRNA in the negative control is quite low (background) while the siRNA contained in the RVG exosomes transfected with siRNA probe reaches as high as 0.8 fmol (RNA)/μg (exosome).

2. In vitro evidence for the entry of pre-S1 exosomes into the hep G2 cell
As shown in Fig.3, by labeling the exosomes with DiI-C16 (red) and hep G2 nucleus with DAPI(blue), it can be seen that the exosomes successfully get into the hep G2 cells

Our modified MVs are just like the “biomissile”, which can be delivered to specific cells and destroy target mRNAs. Our project will open up avenues for therapeutic applications of MVs as biomissile.