Intravenous injection of fusion protein TAT-BDNF relieves acute spinal cord injury in rats

Abstract

Objective To identify the protective in vitro effects of biosynthesized ihsion protein, transaetivator of transcription/brain-derived neurotrophic factor （TAT-BDNF）, on acute spinal cord injury in rats. Methods The recombinant vector termed pTAT-BDNF was constructed by molecular cloning. Both TAT protein transduetion domain and human BDNF were encoded. Purified fllsion protein TAT-BDNF was generated from Escherichia coli BL21 （DE3） . Immunocytochemistry and Western Blot were conducted to analyze the TAT-BDNF content in central nervous system tissue 4 hours after intravenous injection of fusion protein TAT-BDNF. Sprague Dawley rats were divided into a saline control group and a TAT-BDNF group. An animal model of acute compressive spinal cord injury was used to analyze neuroprotective effect of TAT-BDNF on cell apoptosis 3 days later through TUNEL staining. The neuroproteetive effect of TAT-BDNF was also evaluated by testing movements of the hind limb according to the blood-brain barrier （BBB） scales 7 days after the injury. Results hnmunocytochemical and Western Blot analyses of the central nervous system tissue revealed that intravenous TAT-BDNF penetrated BBB throughout the central nervous system. TAT-BDNF significantly decreased the apoptosis ratio in vivo after acute spinal cord injury at 3 days （ n = 6, P 〈 O. 05）. According to the BBB scales, evaluation of hind limb movements for TAT-BDNF treated rats was significantly better than that for TAT-BDNF non-treated ones （P 〈 0. 05） . Conclusion Intravenous fusion protein TAT-BDNF may penetrate BBB and thus relieve acute spinal cord injury. Key words: Spinal cord injury; Blood-brain barrier; Protein transduetion; Rats