Electrospun Fibers With Nerve Growth Factor(NGF) In The Apllication Of Nerve Conduit

Nerve growth factor(NGF) is a kind of cytokines which can promote the growth of nerve cells. Therefore the nerve conduit with NGF sustained release can make nerve repair faster and better. However, simply adding NGF into the polymer solution to fabricate nerve conduit by electrospining is easily to make the protein denaturation, even lead to severe immune response causing the inhibition of NGF secreted by the body. The present study is to achieve a long time sustained release of NGF from the electrospun fibrous nerve conduit with its native conformation prior, in order to repair the nerve defect.In the present study, a improved aqueous-aqueous frozen phase separation method was used to wrap NGF into the polysaccharide particles. The polysaccharide particles were further dispersed into PLLA solution in order to fabricate electrospun fibers, and the particles electrospun fibers were obtained. NGF solution was directly dispersed into PLLA solution to fabricate the emulsion electrospun fibers as a control group. The physical properties of the fibers were characterized. The results indicated that the electrospun fibers had good mechanical properties and elasticity, and had the network structure similar with the ECM. The hydrophilic of fibers was enhanced by adding polysaccharide particles. Elisa kit was used to detect the quantity of NGF. Loading efficiency was 41.44%±12.52%(n=3) in the particles fibers compared with the theoretical quantity and loading efficiency was only 18.69%±7.07%(n=3) in the emulsion fibers. In vitro release of the particles fibers was 28 days, the daily release was relatively uniform and the cumulative release of NGF was 2100 pg. In vitro release of the emulsion fibers was only 11 days with a strong burst release and the cumulative release of NGF was 930 pg. The results indicated that NGF in the particles fibers was well protected and polysaccharide particles had the effect of sustained release of NGF.PC-12 cells were used as model cells, and the adhesion and proliferation of PC-12 cells on the particles fibers was better than those on the emulsion controls.In a rat model, a 10 mm nerve defect was made to determine the effect of nerve repair. Autograft was used as a positive control. Nerve conduits fabricated by the particles fibers and the emulsion fibers for nerve repair were evaluated respectively. The nerve regeneration result was judged by the nerve conduction velocity, and the thickness and quantity of the myelin sheaths. The results indicated that the particles nerve conduit for nerve repair was significantly better than the emulsion method, comparable to the autograft.The electrospun fibrous nerve conduit with NGF polysaccharide particles is very promising in the field of nerve regeneration.