Preparation Of PLGA Magnetic Nanoparticles Loaded With Mngf And Primary Study Of Repairing Rat Sciatic Nerve Injury Under Magnetic Field Guidance

Objective:The purpose of this study was to evaluate the effects of m NGF conjugated with iron oxide nanoparticles(NPs)on repairing sciatic nerve injury in rats under the guidance of an external magnetic field.Methods:Using PLGA as a wrapping material,we covalently conjugated m NGF to iron oxide NPs to prepare the magnetic m NGF-PLGA NP by the single emulsion solvent evaporation method and its physicochemical properties were characterized.Subsequently,the aggregation of drugs in vivo was observed by comparing the MR imaging T2* intensity values under the guidance of an external magnetic field.The model of the left sciatic nerve injury in rats was divided into three groups: Group A,which received an intravenous injection of magnetic m NGF-PLGA NPs once a week guided by external magnetic field;Group B,which received an intravenous injection of m NGF-PLGA NPs without external magnetic guidance;and Group C,which received weekly intravenous injection with m NGF water solution without an external magnetic field.Macroscopic,functional,electrophysiological,and histological assessments of nerves were performed at eight weeks after surgery.Results: The prepared NP sample was a brown suspension with no delimitation in appearance,with the mean size of 205.9 ± 1.2 nm,and it was distributed uniformly.Transmission electron microscope(TEM)confirmed that the NPs are quasi-spherical and contain numerous well-dispersed magnetic iron particles.The NPs show a slow release to the fifth day in vitro.MR imaging indicates that under the guidance of external magnetic field NPs can significantly reduce the T2* signal value and they have a good aggregation in vivo in the injured site.In addition,the sciatic functional index(SFI),the motor nerve conduction velocity and the wet weight recovery ratio of Group A were significantly higher than that of Groups B and C,and the difference was significant(P < 0.05).There was no significant difference between Groups B and C(P > 0.05).Histological observation showed that the arrangement and density of the regenerated nerve fibers in Group A were better than those in Groups B and C.Conclusions: 1.The m NGF-PLGA magnetic nanoparticles with small size,controllable and prolonged slow release effect can be prepared by a single emulsified solvent evaporation method.rats.2.The m NGF-PLGA magnetic nanoparticle can effectively repair peripheral nerve damage under the guidance of external magnetic field.