Loading of therapeutic cell penetrating peptides into extracellular vesicles for pulmonary fibrosis

Extracellular vesicles (EVs) are heterogenous lipid-bilayer wrapped nanoparticles with high potential as next generation drug delivery vehicles. Here we explore the use of EVs as a novel carrier of therapeutic cell penetrating peptides (CPPs). The loading of five different CPPs was characterized using single particle flow cytometry. We demonstrate that the different physiochemical properties of various CPP classes affect their interaction and loading into EVs. We reveal that CPPs partially, and passively, penetrate to the EV lumen, that loading is independent of EV source, and that EV surface proteins play a role in loading efficiency for cationic CPPs (i.e., TAT). Finally, the CPP therapeutic MK2i, which has been previously demonstrated to aid in the suppression of pulmonary fibrosis, was loaded into healthy fibroblast or diseased myofibroblast EVs. MK2i-loaded fibroblast EVs exhibited greater efficacy in both a preventative and treatment in vitro model of pulmonary fibrosis compared to MK2i-loaded myofibroblast EVs and free MK2i peptide. Together, this demonstrates the potential of CPP-loaded EVs as a targeted drug delivery system for the treatment of pulmonary fibrosis.