Abstract: Background Spinal cord injury (SCI) induces global changes in the microRNA (miRNA) expression patterns in the experimental and clinical setting. Identification of dysregulated miRNA could potentially correlate with neurologic outcome and become a prognostic biomarker.
Hypothesis/objectives Based upon our miRNA expression profile data, our objective was to validate miRNA biomarker candidates specifically dysregulated in naturally occuring severe SCI in dogs. We hypothesize that relative expression levels of candidate miRNA would correlate with neurologic grade and outcome.
Animals Serum samples were obtained from a total of 13 dogs (severe: 7 paraplegics without pain perception, moderate: 3 paraplegics with intact pain perception, and 3 healthy control).
Methods This is a prospective study. Total miRNA was isolated and transcribed to cDNA. qRT-PCR was carried out against cfa-miR-23a, cfa-miR-574, chr21_19093, cfa-miR-195, cfa-let-7e, chr10_3880_hsa-miR-920 and chrX_46645_mmu-miR-5101. Relative expression levels were calculated by the Delta-Delta Ct method using cfa-miR-16 as a normalization control. T-test were performed and compared in dogs with favorable and unfavorable neurologic outcomes.
Results Results showed specific up-regulation of cfa-miR-574, chr21_19093 and cfa-miR-195, and down-regulation of cfa-miR-23a, chr10_3880_hsa-miR-920 and chrX_46645_mmu-miR-5101 in dogs without pain perception. cfa-miR-574 demonstrated the most significant (15.9-fold increase, p< 0.04) and consistent up-regulation in the severe group. There was a positive correlation between miRNA expression and neurologic outcome at 6 weeks post-surgery, particularly for cfa-miR-574 in dogs without pain perception (p< 0.02).
Conclusions and Clinical importance The results suggest that dysregulated miRNA expression can be used to predict SCI severity and neurologic outcome. A large cohort study is warranted.
