Identification of key genes influenced by fixation stability in early fracture hematoma and elucidation of their roles in fracture healing.

The present study aimed to identify the key genes influenced by fixation stability in early fracture hematoma and to elucidate their roles in fracture healing. The GSE53256 gene expression profile, including six fracture hematoma tissues, was downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) in the fracture hematoma tissues from old rats with rigid fixation compared with semi-rigid fixation were identified using the limma package. Furthermore, Gene Ontology (GO) enrichment analysis for DEGs was performed using BiNGO, and a protein-protein interaction (PPI) network was constructed based on the Search Tool for the Retrieval of Interacting Genes database. A total of 265 DEGs (158 upregulated and 107 downregulated) in the fracture hematoma tissues were screened out. Additionally, the overrepresented GO terms were mainly associated with the extracellular region, positive regulation of locomotion and response to external stimulus. Transforming growth factor, ß 1 (Tgfß1), chemokine (C-X-C motif) ligand 12 (Cxcl12), matrix metallopeptidase 9 (mmp9) and serpin peptidase inhibitor, clade E, member 1 (serpine1) had higher degrees and were hub nodes in the PPI network. In conclusion, fixation stability may influence the fracture healing process, and important DEGs, including Cxcl12, mmp9, Tgfß1 and serpine1, may be important in this process.

Identification of novel genes associated with fracture healing in osteoporosis induced by Krm2 overexpression or Lrp5 deficiency.

The aim of the present study was to screen potential key genes associated with osteoporotic fracture healing. The microarray data from the Gene Expression Omnibus database accession number GSE51686, were downloaded and used to identify differentially expressed genes (DEGs) in fracture callus tissue samples obtained from the femora of type I collagen (Col1a1)­kringle containing transmembrane protein 2 (Krm2) mice and low density lipoprotein receptor­related protein 5­/­ (Lrp5­/­) transgenic mice of osteoporosis compared with those in wild­type (WT) mice. Enrichment analysis was performed to reveal the DEG function. In addition, protein­protein interactions (PPIs) of DEGs were analyzed using the Search Tool for the Retrieval of Interacting Genes database. The coexpression associations between hub genes in the PPI network were investigated, and a coexpression network was constructed. A total of 841 DEGs (335 upregulated and 506 downregulated) were identified in the Col1a1­Krm2 vs. the WT group, and 50 DEGs (16 upregulated and 34 downregulated) were identified in the Lrp5­/­ vs. the WT group. The DEGs in Col1a1­Krm2 mice were primarily associated with immunity and cell adhesion (GO: 0007155) functions. By contrast, the DEGs in Lrp5­/­ mice were significantly associated with muscle system process (GO: 0003012) and regulation of transcription (GO: 0006355). In addition, a series of DEGs demonstrated a higher score in the PPI network, and were observed to be coexpressed in the coexpression network, and included thrombospondin 2 (Thbs2), syndecan 2 (Sdc2), FK506 binding protein 10 (Fkbp10), 2'­5'-oligoadneylate synthase­like protein 2 (Oasl2), interferon induced protein with tetratricopeptide repeats (Ifit) 1 and Ifit2. Thbs2 and Sdc2 were significantly correlated with extracellular matrix­receptor interactions. The results suggest that Thbs2, Sdc2, Fkbp10, Oasl2, Ifit1 and Ifit2 may serve important roles during the fracture healing process in osteoporosis. In addition, this is the first study to demonstrate that Sdc2, Fkbp10, Oasl2, Ifit1 and Ifit2 may be associated with osteoporotic fracture healing.

Gene markers of fracture healing in early stage and the regulatory mechanism during the process using microarray analysis.

BACKGROUND: The aim of this study was to explore crucial markers and uncover the regulatory mechanisms of fracture healing in the early stage. METHODS: Gene expression profile of GSE45156 was downloaded, in which 3 fractured samples and 3 unfractured samples were used in our present study. Based on the threshold value, differentially expressed genes (DEGs) were selected between two kinds of samples using limma package in R. Enrichment analysis of these DEGs was performed by DAVID software. Furthermore, protein-protein interaction (PPI) network was established integrating information in STRING database, and visualized by Cytoscape software. RESULTS: We identified a set of 960 DEGs including 509 up-regulated and 451 downregulated genes. Biological processes involving RNA splicing and cell cycle were significantly enriched for the up-regulated genes such as Snrpd2, Eftud2, Plk1 and Bub1b, whereas skeletal system development and bone development processes were predominant for down-regulated genes like Ubc. In the constructed PPI network, all the five genes were the predominant nodes, of which Snrpd2 was linked to Eftud2, while Bub1b was to interact with Plk1. CONCLUSION: Five candidate genes crucial for indicating the process of fracture in early stage were identified. Eftud2, Snrpd2, Bub1b and Plk1 might function through the involvement of cell-cycle-related BP, while Ubc might influence the protein degradation during bone development. However, more experimental validations are needed to confirm these results.

Bioinformatics analysis of gene expression profile in callus tissues of osteoporotic phenotype mice induced by osteoblast-specific Krm2 overexpression.

PURPOSE: The aim of this study was to explore the molecular mechanism of fracture healing in osteoporotic mice. METHODS: The gene expression profiles of callus tissues of osteoporotic mice and controls were obtained from Gene Expression Omnibus database. The differentially expressed genes (DEGs) and their related biological function and pathways were investigated. In addition, the protein-protein interaction (PPI) network was constructed for DEG encoding proteins and the differentially expressed transcriptional factor was screened. RESULTS: There were 275 up-regulated genes and 347 down-regulated genes. The collagen metabolic process biological function was significantly enriched by down-regulated genes. Extracellular matrix (ECM)-receptor interaction was a significant pathway that was enriched by differentially expressed genes. In PPI (protein-protein interaction) network, Pcna was the significant node with highest connective degrees. Other hub nodes, such as Ccnb2 and Rrm2, were closely associated with the p53 signaling pathway. Tal1 and Smad6 were found to be differentially expressed transcription factors. CONCLUSION: The dysregulated collagen metabolic process, ECM-receptor interaction and p53 signaling pathway may be responsible for impaired fracture healing of osteoporotic mice. The hub nodes (such as Ccnb2 and Rrm2) and differentially expressed TFs (such as Tal1 and Smad6) play a critical role in bone remodeling of osteoporotic individuals.

Factors affecting directional migration of bone marrow mesenchymal stem cells to the injured spinal cord.

Microtubule-associated protein 1B plays an important role in axon guidance and neuronal migration. In the present study, we sought to discover the mechanisms underlying microtubule-associated protein 1B mediation of axon guidance and neuronal migration. We exposed bone marrow mesenchymal stem cells to okadaic acid or N-acetyl-D-erythro-sphingosine (an inhibitor and stimulator, respectively, of protein phosphatase 2A) for 24 hours. The expression of the phosphorylated form of type I microtubule-associated protein 1B in the cells was greater after exposure to okadaic acid and lower after N-acetyl-D-erythro-sphingosine. We then injected the bone marrow mesenchymal stem cells through the ear vein into rabbit models of spinal cord contusion. The migration of bone marrow mesenchymal stem cells towards the injured spinal cord was poorer in cells exposed to okadaic acid- and N-acetyl-D-erythro-sphingosine than in non-treated bone marrow mesenchymal stem cells. Finally, we blocked phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase 1/2 (ERK1/2) pathways in rabbit bone marrow mesenchymal stem cells using the inhibitors LY294002 and U0126, respectively. LY294002 resulted in an elevated expression of phosphorylated type I microtubule-associated protein 1B, whereas U0126 caused a reduction in expression. The present data indicate that PI3K and ERK1/2 in bone marrow mesenchymal stem cells modulate the phosphorylation of microtubule-associated protein 1B via a cross-signaling network, and affect the migratory efficiency of bone marrow mesenchymal stem cells towards injured spinal cord.

[Percutaneous laser disc decompression for cervical vertigo].

OBJECTIVE: To investigate the curative effect and mechanism of transcutaneous laser disc decompression for the treatment of cervical vertigo. METHODS: From October 2000 to October 2004, 42 patients with cervical vertigo were treated with percutaneous laser disc decompression by applying a Nd: YAG laser (wavelength is 1064 nm). The postoperative follow-up period was more than 2 months, the change of patients' vertigo were observed. RESULTS: All the patients were followed up. The mean follow-up period was 7.5 months (from 2 to 36 months). After 2 months of postoperative, 28 patients' vertigo disappeared (67%), 6 patients' vertigo improved (14%), 8 patients' vertigo did not improve. The effective rate was 81%, there was no complication (infection and nerve injury). CONCLUSIONS: Cervical intervertebral disc protrusion and cervical spine instability irrigate the neck sympathetic nerve, result in the spasm of vertebral artery, which is the main cause of cervical vertigo. Percutaneous laser disc decompression can decrease intradiscal pressure, increase local temperature, remove the spasm of the vertebral artery. The therapeutic effect for the treatment of cervical vertigo was remarkable.