Nanoparticle mediated controlled delivery of dual growth factors

Peripheral nerve functional recovery after nerve injury generally requires multiple growth factors by synergistic effect. However, the optical combination of multiple synergistic growth factors for axonal regeneration has been scarcely considered up to now. Meanwhile, the use of growth factors in promoting nerve regeneration was limited by its short biological half-life in vivo, its vulnerability to structure disruption or hydrolyzation, leading to loss of bioactivity. Herein, a novel polymeric nanoparticle delivery system composed of heparin and ɛ-poly-L-lysine (PL) was prepared for control release of nerve growth factor (NGF) and basic fibroblast growth factor (bFGF). The nanoparticles were synthesized by polyelectrolyte complexation in aqueous solution at room temperature, followed by cross-linking with biological genipin. The obtained nanoparticles had a spherical shape, with a mean diameter of about 246 nm, and high growth factors encapsulation efficiency as well as good stability. NGF and bFGF were encapsulated in the nanoparticles and showed a continuous and slow release behavior in vitro. The bioactivities of the released growth factors were evaluated, and exhibited the synergistic effect. The controlled release of the dual synergistic growth factors would improve the treatment of peripheral nerve injury to mimic the natural cellular microenvironments.