Exosome protein engineering: XPack protein packaging vectors

The XPack™ technology from System Biosciences enables cell-mediated generation of ready-to-use exosomes packaged with any protein of choice. Incorporating an optimised ‘XPack’ peptide sequence within the XPack cloning and expression lentivectors, your protein of interest is targeted to the interior exosomal membrane within a producer cell line. These engineered exosomes can then be easily isolated and delivered to target cells.

Benefits of using the XPack technology
•    Two promoter options for expression in a wide range of cells
•    Comes with a choice of three reporters (GFP, RFP, luciferase)
•    Bioluminescent exosome generation possible
•    Ideal for exosome labelling, cargo tracking and stable cell line generation
•    XPack peptide tag for robust exosome targeting

SBI cloned the CDKN1B gene into CMV-XP-MCS-EF1α-Puro Cloning Lentivector (Cat.# XPAK510PA-1), transfected this construct into HEK293 cells, and isolated exosomes after 48 hours using ExoQuick-TC®. SBI then added 5, 50, or 100 µg of XPack-CDKN1B exosomes to approximately 5000 HEK-293 target cells in 96-well tissue culture plates at 24-hour intervals over the course of 72 hours. Exosomes isolated from non-transfected cells were used for controls. Cellular proliferation was quantified using an MTT Assay (Millipore catalog # CT02) and normalised to HEK-293 cells treated with control exosomes. XPack-CDKN1B exosomes consistently reduce the rate of cellular proliferation. 

XPack efficiently packages GFP into exosomes

(Upper panel) XPack-GFP localisation during packaging. (Lower panel) Western blot showing robust loading of GFP into the isolated exosomes. 

Material available for download
XPack product sheet
XPack user manual

XPack technical references & citations