Objective      To prepare and investigate the characteristic of biodegradable mPEG-PLA microspheres as carriers for controlled nerve growth factor (NGF) delivery

and the sustained release rate in vitro.        Methods      mPEG-PLA was utilized as delivery material to prepare the NGF microspheres by multiple emulsion method. The physical surface of microspheres was detected

and the content of NGF in the microspheres was evaluated by ELISA. Dialysis was used to examine the in vitro drug release.        Results      The microspheres were spherical in shape

and had a smooth surface. The particle size was uniform with a size of (74.2±21.3) μm. Drug-loading amount was [(2.13±0.24)×10

-5

]

% and the entrapment rate was (77.3±1

.8)%. There was no burst release found in vitro. The release rate was 27.36% of total amount in 24 h. The accumulative sustained release rate was 72.34% in 3 weeks.        Conclusion      mPEG-PLA-NGF microspheres have a good physical performance and sustained release character in vitro.