Saikosaponin a increases interleukin-10 expression and inhibits scar formation after sciatic nerve injury.

Nerve scarring after peripheral nerve injury can severely hamper nerve regeneration and functional recovery. Further, the anti-inflammatory cytokine, interleukin-10, can inhibit nerve scar formation. Saikosaponin a (SSa) is a monomer molecule extracted from the Chinese medicine, Bupleurum. SSa can exert anti-inflammatory effects in spinal cord injury and traumatic brain injury. However, it has not been shown whether SSa can play a role in peripheral nerve injury. In this study, rats were randomly assigned to three groups. In the sham group, the left sciatic nerve was directly sutured after exposure. In the sciatic nerve injury (SNI) + SSa and SNI groups, the left sciatic nerve was sutured and continuously injected daily with SSa (10 mg/kg) or an equivalent volume of saline for 7 days. Enzyme linked immunosorbent assay results demonstrated that at 7 days after injury, interleukin-10 level was considerably higher in the SNI + SSa group than in the SNI group. Masson staining and western blot assay demonstrated that at 8 weeks after injury, type I and III collagen content was lower and nerve scar formation was visibly less in the SNI + SSa group compared with the SNI group. Simultaneously, sciatic functional index and nerve conduction velocity were improved in the SNI + SSa group compared with the SNI group. These results confirm that SSa can increase the expression of the anti-inflammatory factor, interleukin-10, and reduce nerve scar formation to promote functional recovery of injured sciatic nerve.

Gene expression profile identifies potential biomarkers for human intervertebral disc degeneration.

The present study aimed to reveal the potential genes associated with the pathogenesis of intervertebral disc degeneration (IDD) by analyzing microarray data using bioinformatics. Gene expression profiles of two regions of the intervertebral disc were compared between patients with IDD and controls. GSE70362 containing two groups of gene expression profiles, 16 nucleus pulposus (NP) samples from patients with IDD and 8 from controls, and 16 annulus fibrosus (AF) samples from patients with IDD and 8 from controls, was downloaded from the Gene Expression Omnibus database. A total of 93 and 114 differentially expressed genes (DEGs) were identified in NP and AF samples, respectively, using a limma software package for the R programming environment. Gene Ontology (GO) function enrichment analysis was performed to identify the associated biological functions of DEGs in IDD, which indicated that the DEGs may be involved in various processes, including cell adhesion, biological adhesion and extracellular matrix organization. Pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) demonstrated that the identified DEGs were potentially involved in focal adhesion and the p53 signaling pathway. Further analysis revealed that there were 35 common DEGs observed between the two regions (NP and AF), which may be further regulated by 6 clusters of microRNAs (miRNAs) retrieved with WebGestalt. The genes in the DEG­miRNA regulatory network were annotated using GO function and KEGG pathway enrichment analysis, among which extracellular matrix organization was the most significant disrupted biological process and focal adhesion was the most significant dysregulated pathway. In addition, the result of protein­protein interaction network modules demonstrated the involvement of inflammatory cytokine interferon signaling in IDD. These findings may not only advance the understanding of the pathogenesis of IDD, but also identify novel potential biomarkers for this disease.

Neurotrophin-4 induces myelin protein zero expression in cultured Schwann cells via the TrkB/PI3K/Akt/mTORC1 pathway.

Myelin formation during peripheral nervous system development, as well as myelin repair after injury and in disease, requires multiple intrinsic and extrinsic signals. Neurotrophin-4 (NT-4) is a member of the neurotrophin family, which regulates the development of neuronal networks by participating in the growth of neuronal processes, synaptic development and plasticity, neuronal survival, and differentiation. However, the intracellular signaling pathways by which NT-4 participates in myelination by Schwann cells remain elusive. In this study, we examined the effects of NT-4 on the expression of compact myelin proteins in cultured Schwann cells. Using real-time quantitative RT-PCR and western blotting, we found that NT-4 could significantly enhance the expression of myelin protein zero (MPZ) but not the expression of myelin basic protein or peripheral myelin protein 22. Further, knockdown of truncated TrkB with small interfering RNA could eliminate the effect of NT-4 on MPZ expression. Moreover, we demonstrated that the NT-4-enhanced MPZ expression depended on Akt and mTORC1 signaling. Taken together, these results suggest that NT-4 binds TrkB to enhance the expression of MPZ in Schwann cells, probably through the PI3K/Akt/mTORC1 signaling pathway, thus contributing to myelination.

Dysregulated miR-133a Mediates Loss of Type II Collagen by Directly Targeting Matrix Metalloproteinase 9 (MMP9) in Human Intervertebral Disc Degeneration.

STUDY DESIGN: A microRNA (miRNA) study using Solexa sequencing. OBJECTIVE: The purpose of this study was to identify intervertebral disc degeneration (IDD)-specific miRNA expression profile, and to validate its biological function. SUMMARY OF BACKGROUND DATA: Accumulating evidence indicates that miRNAs play a critical role in IDD, but the role of specific miRNAs involved in this entity remains unclear. METHODS: MiRNA expression profile was determined in nucleus pulposus (NP) tissues from patients with IDD and controls, employing Solexa sequencing and quantitative real-time PCR (qRT-PCR). Biological functions of differential expression miRNAs were further investigated. Luciferase reporter assays and western blotting were performed to determine miRNA targets. RESULTS: We identified 31 miRNAs that were differentially expressed (22 upregulated and nine downregulated) in patients compared with controls. After qRT-PCR confirmation, miR-133a was significantly down-regulated in degenerative NP tissues. Moreover, its level was inversely correlated with grade of disc degeneration. Through gain- and loss-of-function studies, miR-133a was demonstrated to significantly promote type II collagen expression in NP cells. MMP9 was identified as a target of miR-133a. Knockdown of MMP9 induced effects on NP cells similar to those induced by miR-133a. Expression of MMP9 was inversely correlated with miR-133a expression in degenerative NP tissues. CONCLUSION: These results suggest that the downregulation of miR-133a induces type II collagen loss by directly targeting MMP9. Our findings also highlight miR-133a as a novel hopeful therapeutic target for IDD. LEVEL OF EVIDENCE: 3.

MicroRNA-221 Regulates Hypertrophy of Ligamentum Flavum in Lumbar Spinal Stenosis by Targeting TIMP-2.

STUDY DESIGN: A study of lumbar ligamentum flavum (LF). OBJECTIVE: The aim of this study was to identify LF hypertrophy related microRNAs (miRNAs) expression profile and to investigate the role of miRNAs in the development of LF hypertrophy in lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: Although histologic and biologic literature on LF hypertrophy is available, the pathomechanism is still unknown. Accumulating evidence suggests that microRNAs (miRNAs) participate in many physiologic processes, including cell proliferation, differentiation, and fibrosis, but the role of specific miRNAs involved in LF hypertrophy remains elusive. METHODS: An initial screening of LF tissues miRNA expression by miRNA microarray was performed using samples from 10 patients and 10 controls, respectively. Subsequently, differential expression was validated using qRT-PCR. Then, functional analysis of the miRNAs in regulating collagens I and III expression was carried out. Western blotting and luciferase reporter assay were also used to detect the target gene. In addition, the thickness of the LF at the level of the facet joint was measured on axial T1-weighted magnetic resonance images. RESULTS: We identified 18 miRNAs that were differentially expressed in patients compared with controls. Following qRT-PCR confirmation, miR-221 was significantly lower in LF tissues of patients than controls. The LF was significantly thicker in patients than that in controls. Bioinformatics target prediction identified tissue inhibitors of matrix metalloproteinase (TIMP)-2 as a putative target of miR-221. Furthermore, luciferase reporter assays demonstrated that miR-221 directly targets TIMP-2 and affects the protein expression of TIMP-2 in fibroblasts isolated from LF. Of note, miR-221 mimic reduced mRNA and protein expression of collagens I and collagen III in fibroblasts isolated from LF. CONCLUSION: The downregulation of miR-221 might contribute to LF hypertrophy by promoting collagens I and III expression via the induction of TIMP-2. Our study also underscores the potential of miR-221 as a novel therapeutic target in LSS. LEVEL OF EVIDENCE: 3.

Upregulated Ras/Raf/ERK1/2 signaling pathway: a new hope in the repair of spinal cord injury.

An increasing number of studies report that the Ras/Raf/extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway has a death-promoting apoptotic function in neural cells. We hypothesized that the Ras/Raf/ERK1/2 signaling pathway may be abnormally regulated in rat injured spinal cord models. The weight drop method was used to establish rat spinal cord injury at T9. Western blot analysis and immunohistochemical staining revealed Ras expression was dramatically elevated, and the phosphorylations of A-Raf, B-Raf and C-Raf were all upregulated in the injured spinal cord. Both mitogen-activated protein kinase kinase 1/2 and ERK1/2, which belong to the Ras/Raf signaling kinases, were upregulated. These results indicate that Ras/Raf/ERK1/2 signaling may be upregulated in injured spinal cord and are involved in recovery after spinal cord injury.

Computer navigation in total hip arthroplasty: a meta-analysis of randomized controlled trials.

OBJECTIVE: Traditional operation frequently depends on experience of doctors and anatomic landmark visual observation, which often leads to deviation in acetabular prosthesis implantation. Computer navigation technique greatly improves accuracy of prosthesis implantation. The present meta-analysis aimed at assessing the accuracy and clinical significance of computer navigation for acetabular implantation. METHODS: All studies published through March 2013 were systematically searched from PubMed, EMBnse, Science Direct, Cechrane library and other databases. Relevant journals or conference proceedings were searched manually. Only randomized controlled trials (RCTs) were included. Two independent reviewers identified and assessed the literature. Mean difference (MD) and Odds ratio (OR) of radiologic and clinical outcomes were pooled throughout the study between navigated and conventional THA. The meta-analysis was conducted by RevMan 5.1 software. RESULTS: Thirteen studies were included in the review, with a total sample size of 1071 hips. Statistically significant differences were observed between navigated and conventional groups in the number of acetabular cups implanted beyond the safe zone [OR = 0.13, 95% confidence interval (CI) (0.08-0.22); P < 0.00001], operative time [MD = 19.87 min, 95% CI (14.04-24.35); P < 0.00001] and leg length discrepancy [MD = -4.16 mm, 95% CI (-7.74 to -1.48); P = 0.004]. No significant differences in cup inclination, anteversion, incidence of postoperative dislocation or deep vein thrombosis were found. CONCLUSIONS: The present meta-analysis indicated that the use of computer navigation in patients undergoing THA improves the precision of acetabular cup placement by decreasing the number of outliers, and decreases leg length discrepancy. More high quality RCTs are required to further confirm our results.

[Dynamic changes of LDH and HBDH activity in rabbit serum after low voltage electrical injury].

OBJECTIVE: To investigate changes of LDH and HBDH activity in rabbit serum after non-thermal low voltage electrical injury and to provide diagnostic criteria for non-thermal low voltage electrical injury. METHODS: Forty New Zealand rabbits were randomly distributed into control group and electrical injury group (EI-groups; designated 7 time points: 0 h, 2 h, 4 h, 12 h, 1 d, 2 d, 3 d), 5 rabbits per each group. EI-groups were treated with the method of non-thermal low voltage electrical injury established in our laboratory. Ventricular blood (5 mL) was obtained under anesthesia at designated time points after electrical injury. The activities of LDH and HBDH were measured. RESULTS: Dynamic changes were observed with certain patterns from target serum enzyme activities after electrical injury. Compared with control group, the activities of LDH increased markedly at 4 h, 12 h, and on days 1, 2, and 3 after injury (4 h, 12 h, and day 1 P<0.01; day 2 and day 3 P<0.05). Activities of HBDH increased markedly at day 2 and day 3 after injury (P<0.05). The ratio of HBDH/LDH decreased markedly at 2 h, 4 h, and 12 h after injury (P<0.01). CONCLUSION: Dynamic changes of LDH and HBDH activities may be useful in diagnosis of non-thermal low voltage electrical injury and in estimation of post injury intervals.