Significant Enhancement of Fibroblast Migration, Invasion, and Proliferation by Exosomes Loaded with Human Fibroblast Growth Factor 1

Exosomes possess several inherent properties that make them ideal for biomedical applications, including robust stability, biocompatibility, minimal immunogenicity, and the ability to cross biological barriers. These natural nanoparticles have recently been developed as drug delivery vesicles. To do so, therapeutic molecules must be efficiently loaded into exosomes first. Very recently, we developed a cell-penetrating peptide (CPP)-based platform for loading of nucleic acids and small molecules into exosomes by taking advantage of the membrane-penetration power of CPPs. Here, we extended this simple but effective platform by loading a protein cargo into exosomes isolated from either mesenchymal stem cells from three different sources or two different cancer cell lines. The protein cargo is a fusion protein YARA-FGF1-GFP through the covalent conjugation of a model CPP called YARA to human fibroblast growth factor 1 (FGF1) and green fluorescence protein (GFP). Loading of YARA-FGF1-GFP into exosomes was time-dependent and reached a maximum of about 1600 YARA-FGF1-GFP molecules in each exosome after 16 h. The ladened exosomes were effectively internalized by mammalian cells, and subsequently, the loaded protein cargo YARA-FGF1-GFP was delivered intracellularly. In comparison to YARA, YARA-FGF1-GFP, the unloaded exosomes, and the exosomes loaded with YARA, the exosomes loaded with YARA-FGF1-GFP substantially promoted the migration, proliferation, and invasion capabilities of mouse and human fibroblasts, which are important factors for wound repair. The work extended our CPP-based exosomal cargo loading platform and established a foundation for developing novel wound-healing therapies using exosomes loaded with FGF1 and other growth factors.