Incorporating BMSCs-Derived Exosomes into Coaxial Electrospun Nanofibers for Bone Regeneration

Objectives: Exosomes, nanoscale extracellular vesicles functioning as cell-to-cell communicators, are playing promising therapeutic roles in bone tissue engineering. However, its clinical use has several notable limitations because exosomes are sensitive to the surrounding environments.In this study, we aimed to incorporate bone marrow mesenchymal stem cells(BMSCs)-derived exosomes into silk fibroin/polycaprolactone (SF/PCL) nanofibers by coaxial electrospinning to determine the application in bone regeneration.
Methods: Exosomes were isolated from rat bone marrow mesenchymal stem cells by gradient ultracentrifugation. Transmission electron microscope ,western blot and nanosight analysis were used to identified this extracellular vesicle. SF/PCL scaffolds containing different ratios of BMSCs-derived exosomes were prepared by coaxial electrostatic spinning. We characterized the nano fibers by scanning electron microscope and transmission electron microscope.Then the release of exosomes from the nanofiber was quantified. Cytotoxicity were tested by CCK-8. Confocal microscopy was used to determine biocompatibility of this composite material.In vivo function of BMSCs-derived exosomes incorporated coaxial electrospun nanofibers was determined in a rat cranial defects animal model.The bone regeneration capacity was evaluated by radiographic and histological exammination methods.
Results: It was suggested that the fibricated biomaterial achieved an uniform distribution of fiber diameters and displayed satisfactory biocompatibility.Exosomes could be protected by sheath layer and slowly released from coaxial electrospun nanofibers. In addition, in vivo animal experiment manifested the coaxial electrospun nanofibers incorporating with BMSCs-derived exosomes could significantly enhance bone healing of rat cranial defects.
Conclusions: This study explored the possibility of incorporating BMSCs-derived exosomes into nano fibers, using the method of coaxial electrospinning and showed the promising use of exosomes-loaded scaffolds in bone tissue engineering.