Electrospun Chitosan Nanofibers for the Controlled Released of Bioactive FGF-2 and Mesenchymal Stem Cell Osteogenic Differentiation

Scaffolds prepared from the polysaccharide chitosan have gained considerable attention in the past several years for tissue engineering applications because of the many attractive properties of chitosan. Electrospinning of polymeric solutions has becoming increasingly popular as a simple and reproducible technique for creating nanofibrous scaffolds with a wide range of geometry, porosity, and alignment. In this work, chitosan nanofibers were created via electrospinning and they were investigated to be used as a platform for growth factor delivery and mesenchymal stem cell (MSC) activation. Basic fibroblast growth factor (FGF-2) was adsorbed on polyelectrolyte complex nanoparticles (PCN) and these were successfully adsorbed and released from the nanofibers. The release of the PCN was controlled by using layer-by-layer assembly of poyelectrolyte multilayers (PEM). Lastly, the nanofiber scaffolds were tested in vitro using bone marrow-derived ovine and equine MSCs for applications in bone regeneration. Controlled release of FGF-2 is achieved over a period of 27 days and its biological activity is preserved. MSCs were successfully seeded on chitosan nanofibers and both equine and ovine MSCs demonstrated a higher alkaline phosphatase production when seeded on fibers as compared to flat polystyrene surfaces. Chitosan nanofibers promote osteogenic differentiation even in the absence of chemical cues. Future work will be performed by delivering growth factors that promote MSC differentiation using chitosan nanofibers and polysaccharide-based nanomaterials.