Protective effect of liposome-mediated glial cell line-derived neurotrophic factor gene transfer in vivo on motoneurons following spinal cord injury in rats.

OBJECTIVE

To investigate the effect of liposome-mediated glial cell line-derived neurotrophic factor (GDNF) gene transfer in vivo on spinal cord motoneurons after spinal cord injury (SCI) in adult rats.

METHODS

Sixty male Sprague-Dawley rats were divided equally into two groups: GDNF group and control group. The SCI model was established according to the method of Nystrom, and then the DC-Chol liposomes and recombinant plasmid pEGFP-GDNF cDNA complexes were injected into the injured spinal cord. The expression of GDNF cDNA 1 week after injection was detected by RT-PCR and fluorescence microscope. We observed the remaining motoneurons in the anterior horn and the changes of cholinesterase (CHE) and acid phosphatase (ACP) activity using Nissl and enzyme histochemistry staining. The locomotion function of hind limbs of rats was evaluated using inclined plane test and BBB locomotor scale.

RESULTS

RT-PCR and fluorescence observation confirmed the presence of expression of GDNF cDNA 1 week and 4 weeks after injection. At 1, 2, 4 weeks after SCI, the number of motoneurons in the anterior horn in GDNF group (20.4+/-3.2, 21.7+/-3.6, 22.5+/-3.4) was more than that in control group (16.8+/-2.8, 17.3+/-2.7, 18.2+/-3.2, P<0.05). At 1, 2 weeks after SCI, the mean gray of the CHE-stained spinal motoneurons in GDNF group (74.2+/-25.8, 98.7+/-31.6) was less than that in control group (98.5+/-32.2, 134.6+/-45.2, P<0.01), and the mean gray of ACP in GDNF group (84.5+/-32.6, 79.5+/-28.4) was more than that in control group (61.2+/-24.9, 52.6+/-19.9, P<0.01). The locomotion functional scales in GDNF group were higher than that in control group within 1 to 4 weeks after SCI (P<0.05).

CONCLUSIONS

GDNF gene transfer in vivo can protect motoneurons from death and degeneration induced by incomplete spinal cord injury as well as enhance locomotion functional restoration of hind limbs. These results suggest that liposome-mediated delivery of GDNF cDNA might be a practical method for treating traumatic spinal cord injury.