Effects of poly lactic-co-glycolic acid-Nogo A antibody delayed-release microspheres on regeneration of injured spinal cord in rats

摘要

BACKGROUND:Nogo A antigen is the major inhibiting factor blocking regeneration of the injured spinal cord.Neutralizing Nogo A antigens using Nogo A antibodies may help promote neurite regeneration and nervous function recovery.For successful regeneration,sustained release of the antibody from a biodegradable material loaded with Nogo A antibodies to the injury site is required. OBJECTIVE:To compare the therapeutic effects of poly lactic-co-glycolic acid(PLGA)-Nogo A antibody delayed-release microspheres and Nogo A antibody alone on spinal regeneration in Sprague-Dawley rats with complete transverse injury to the spinal cord. DESIGN,TIME AND SETTING:A randomized,controlled animal trial was performed at the Pharmacological Laboratory of West China Center of Medical Sciences,Sichuan University, between October 2007 and January 2008. MATERIALS:Goat anti-rat Nogo A monoclonal antibody was purchased from Santa,American; goat anti-rat neurofilament 200 monoclonal antibody was from Zhongshan Goldenbridge,Beijing, China;PLGA-Nogo A antibody delayed-release microspheres were provided by the College of Pharmacy,Sichuan University. METHODS:A total of 36 adult female Sprague Dawley rats were used to establish models of completely transected spinal cord injury,at T_(10).Animals were randomly divided into three groups (n=12):model,Nogo A antibody alone,and Nogo A antibody delayed-release microsphere groups. After transverse injury of the spinal cord,50μL normal saline solution,50μL normal saline solution containing 50μg Nogo A antibody,and 50μL normal saline solution containing 50μg Nogo A antibody microspheres were administered to the respective groups at the injury site. MAIN OUTCOME MEASURES:The expression of Nogo A and neurofilament 200 in injured spinal cord was tested immunohistochemically,and motor function of rats was assessed by Basso-Beattie-Bresnahan(BBB) locomotor rating scale. RESULTS:Four weeks after injury,expression of Nogo A in microsphere group was significantly less than model and Nogo A antibody alone groups(P0.05).Ten weeks after injury, microsphere group showed a significantly greater expression of neurofilament 200 than model and Nogo A antibody alone groups(P0.05).At postoperative weeks 5 and 6,the score of BBB locomotor rating scale in microsphere group was significantly greater than the model group(P<0.05),and at postoperative weeks 7-10,the score was much greater than model and Nogo A antibody alone groups(P<0.05). CONCLUSION:Nogo A antibody delayed-release microspheres decreased Nogo A expression, increased neurofilament 200 expression in the injured spinal cord of rats,and promoted recovery of motor function through sustained drug release over a long-term period.