ABSTRACT
Exosome-derived long non-coding RNAs (lncRNAs) are extensively engaged in recovery and repair of the injured spinal cord, through different mechanisms. However, to date no study has systematically evaluated the differentially expressed lncRNAs involved in the development of spinal cord injury. Thus, the aim of this study was to identify key circulating exosome-derived lncRNAs in a rat model of spinal cord injury and investigate their potential actions. To this end, we established a rat model of spinal cord hemisection. Circulating exosomes were extracted from blood samples from spinal cord injury and control (sham) rats and further identified through Western blotting and electron microscopy. RNA was isolated from the exosomes and sequenced. The enrichment analysis demonstrated that there were distinctively different lncRNA and mRNA expression patterns between the two groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and Gene Ontology (GO) functional analysis were performed to determine the possible involvements of upregulated and downregulated lncRNAs in various pathways and different biological processes, as well as their cellular locations and molecular functions. Furthermore, quantitative reverse transcription-polymerase chain reaction showed that the expression of five lncRNAs--ENSRN0T00000067908, XR_590093, XR_591455, XR_360081, and XR_346933--was increased, whereas the expression of XR_351404, XR_591426, XR_353833, XR_590076, and XR_590719 was decreased. Of note, these 10 lncRNAs were at the center of the lncRNA-miRNA-mRNA coexpression network, which also included 198 mRNAs and 41 miRNAs. Taken together, our findings show that several circulating exosomal lncRNAs are differentially expressed after spinal cord injury, suggesting that they may be involved in spinal cord injury pathology and pathogenesis. These lncRNAs could potentially serve as targets for the clinical diagnosis and treatment of spinal cord injury.
ABSTRACT
Insulin-like growth factor 1 (IGF-1) is a potential nutrient for nerve repair. However, it is impractical as a therapy because of its limited half-life, rapid clearance, and limited target specificity. To achieve targeted and long-lasting treatment, we investigated the addition of a binding structure by fusing a collagen-binding domain to IGF-1. After confirming its affinity for collagen, the biological activity of this construct was examined by measuring cell proliferation after transfection into PC12 and Schwann cells using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Immunofluorescence staining was conducted to detect neurofilament and microtubule-associated protein 2 expression, while real time-polymerase chain reaction was utilized to determine IGF-1 receptor and nerve growth factor mRNA expression. Our results demonstrate a significant increase in collagen-binding activity of the recombinant protein compared with IGF-1. Moreover, the recombinant protein promoted proliferation of PC12 and Schwann cells, and increased the expression of neurofilament and microtubule-associated protein 2. Importantly, the recombinant protein also stimulated sustained expression of IGF-1 receptor and nerve growth factor mRNA for days. These results show that the recombinant protein achieved the goal of targeting and long-lasting treatment, and thus could become a clinically used factor for promoting nerve regeneration with a prolonged therapeutic effect.
ABSTRACT
The temporal expression of microRNA after spinal cord ischemia/reperfusion injury is not yet fully understood. In the present study, we established a model of spinal cord ischemia in Sprague-Dawley rats by clamping the abdominal aorta for 90 minutes, before allowing reperfusion for 24 or 48 hours. A sham-operated group underwent surgery but the aorta was not clamped. The damaged spinal cord was removed for hematoxylin-eosin staining and RNA extraction. Neuronal degeneration and tissue edema were the most severe in the 24-hour reperfusion group, and milder in the 48-hour reperfusion group. RNA amplification, labeling, and hybridization were used to obtain the microRNA expression profiles of each group. Bioinformatics analysis confirmed four differentially expressed microRNAs (miR-22-3p, miR-743b-3p, miR-201-5p and miR-144-5p) and their common target genes (Tmem69 and Cxcl10). Compared with the sham group, miR-22-3p was continuously upregulated in all three ischemia groups but was highest in the group with no reperfusion, whereas miR-743b-3p, miR-201-5p and miR-144-5p were downregulated in the three ischemia groups. We have successfully identified the key genes expressed at different stages of spinal cord ischemia/reperfusion injury, which provide a reference for future investigations into the mechanism of spinal cord injury.
