Effect Of Chitosan Membrane With Sustained-release FK506 On Nerve Regeneration After Spinal Cord Injury In Rats

Objective: To investigate the effect of implanting chitosan membrane composite of slow-release FK506 on nerve regeneration and functional recovery after spinal cord injury(SCI) in rat.Methods:1. 80 SD rats were divided into four groups, group A accepted T10 laminectomy only, and SCI was induced after laminectomy by modified Allen's Weight Drop in the other three groups. Group B was directly sutured after injury, plain chitosan membrane was implanted on dura in group C, while chitosan membrane with slow-release FK506 was implanted in group D. Nerve regeneration and functional recovery were observed in 1 week, 2 weeks, 3 weeks and 4 weeks after surgery.2. Recovery of hindlimb locomotor function was assessed in open field according to CBS combining score.3. Neurons and reurites expressing NF200 near lesion epicenter, as well as astrocytes expressing GFAP were observed by immunofluorescence and histochemistry. Use image analysis system to calculate gray value of positive cells in each group.4. Expression of GAP-43 mRNA in each group were observed by RT-PCR, using image analysis system to calculate the gray value of each sample.5. Statistical analysis : Data are expressed as mean±standard error, use SPSS 16.0 software package for single-factor analysis and differences were considered statistically significant at P <0.01 level. Results :1. locomotor function of group B, C and D gradually recovered after spinal cord contusion . B, C functional recovery of the two groups are basi- cally the same. From the beginning of the second week, scores in group D were more significantly increased than B and C, the difference was statistically significant.2. AU value of NF200 in D group treated with chitosan membrane with slow-release FK506 were significantly higher than group B and C,since the beginning of the second week, with statistical significance (P <0.01).In the fourth week ,immunofluorescence, fewer and shorter axons regenerated through the injury area in group B and C, with disorder and lighter staining. Regeneration of axons in group D was better than group B and C. And compare with group B and C, within each time point, D group retained less GFAP-positive cells, smaller cell body, smaller process and less glial scar the formation around epicenter .3. During total postoperative observation period, GAP-43 mRNA expression in group A did not change significantly, maintaining a low expression state. GAP-43 mRNA expression in group B, C and D gradually decreased. And since one week postoperative, GAP-43 mRNA level in group A significantly higher than group B and C, and continued until four-weeks timepoint.Results:1.Chitosan membrane composite of slow-release FK506 can promote nerve regeneration after spinal cord contusion in rats.2. Chitosan membrane composite of slow-release FK506 can promote functional recovery after spinal cord contusion in rats.