Tenascin-C promotes endochondral ossification and fracture healing through Hedgehog and Hippo signaling.

Fractures are frequent and severe musculoskeletal injuries. This study aimed to investigate the function of tenascin-C (TNC) in regulating chondrogenic during fracture healing and elucidate the underlying molecular mechanisms. A well-established femur fracture model in male C57BL/6J mice was used to transect the middle diaphysis of the femur. To identify the essential role of TNC, shTNC lentiviruses or TNC protein were administered in the animal model. Micro-CT analysis, histologic analysis, immunostaining assays, and gene expression analysis were employed to investigate the effect of TNC during fracture healing. An in vitro mesenchymal stem cell culture system was developed to investigate the role and molecular mechanism of TNC in regulating chondrogenesis. TNC expression was induced at the inflammatory phase and peaked at the cartilaginous callus phase during fracture healing. Knockdown of TNC expression in callus results in decreased callus formation and impaired fracture healing. Conversely, administration of exogenous TNC promoted chondrogenic differentiation, cartilage template formation and ultimately improved fracture healing. Both the Hedgehog and Hippo signaling pathways were found to be involved in the pro-chondrogenic function of TNC. Our observations demonstrate that TNC is a crucial factor responsible for endochondral ossification in fracture healing and provide a potential therapeutic strategy for promoting fracture healing.

CXCL12/CXCR4-Rac1-mediated migration of osteogenic precursor cells contributes to pathological new bone formation in ankylosing spondylitis.

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by inflammatory back pain and spinal ankylosis due to pathological new bone formation. Here, we identified CXCL12 as a critical contributor to pathological new bone formation through recruitment of osteogenic precursor cells (OPCs). CXCL12 was found highly expressed in the regions that would potentially develop pathological new bone. OPCs were recruited to the regions where CXCL12 was up-regulated. Inhibition of CXCL12/CXCR4 axis with AMD3100 or conditional knockout of CXCR4 attenuated OPCs migration and subsequent pathological new bone formation in animal models of AS. By contrast, a genetically engineered animal model with CXCL12 overexpression developed a joint ankylosis phenotype. Furthermore, Rac1 was found essential for OPCs migration and pathological new bone formation. These findings ravel the novel role of CXCL12 in AS and indicate a potential strategy for targeting the CXCL12/CXCR4-Rac1 axis to prevent progression of axial skeleton ankylosis.

LncRNA XIST facilitates S1P-mediated osteoclast differentiation via interacting with FUS.

INTRODUCTION: The diagnosis and treatment of osteoporosis, a frequent age-related metabolic bone disorder, remain incomprehensive and challenging. The potential regulatory role of lncRNA XIST and sphingosine kinase 1 (SPHK1) pathway need experimental investigations. MATERIALS AND METHODS: RAW264.7 cells and BMMs were obtained for in vitro studies and 30 ng/mL RANKL was implemented for induction of osteoclast differentiation. The suppressing of lncRNA XIST, SPHK1 and fused in sarcoma (FUS) was achieved using small hairpin RNA, while overexpression of XIST and FUS was constructed by pcDNA3.1 vector system. Tartrate-resistant acid phosphatase (TRAP) staining was used for observation of formation of osteoclasts. RNA-pulldown analysis and RNA binding protein immunoprecipitation (RIP) was implemented for measuring mRNA and protein interactions. RT-qPCR was conducted to determining mRNA expression, whereas ELISA and Western blotting assay was performed for monitoring protein expression. RESULTS: RANKL induced osteoclast differentiation and upregulated expression of osteoclastogenesis-related genes that included NFATc1, CTSK, TRAP and SPHK1 and the level of lncRNA XIST in both RAW264.7 cells and BMMs. However, knockdown of lncRNA XIST or suppressing SPHK1 significantly reserved the effects of RANKL. LncRNA XIST was further demonstrated to be interacted with FUS and increased the stability of SPHK1, indicating its ability in promoting osteoclast differentiation through SPHK1/S1P/ERK signaling pathway. CONCLUSION: LncRNA XIST promoted osteoclast differentiation via interacting with FUS and upregulating SPHK1/S1P/ERK pathway.

Molecular Imaging of Collagen Destruction of the Spine.

As the leading cause of disability worldwide, low back pain is commonly caused by biomechanical and catabolic disruptions to key structures of the spine, such as intervertebral discs and facet joints. To date, accurate, noninvasive detection of microdestruction within these tissues remains an elusive goal. Here, we report an in vivo imaging approach based on a collagen hybridizing peptide (CHP) that specifically targets disruption to the extracellular matrix architecture at the molecular scale─the denatured collagen molecules. Utilizing fluorescently labeled CHPs, live animal imaging, and light sheet fluorescence microscopy, we mapped collagen destruction in the lumbar spines in 3D, revealing that under normal conditions collagen destruction was localized to load-bearing anatomical structures including annulus fibrosus of the disc and the facet joints, where aging, tensile force (hindlimb suspension), and disc degeneration (needle puncture) escalated the CHP-binding in specific mouse models. We showed that targeting denatured collagen molecules allowed for an accurate, quantifiable interrogation of the structural integrity of these spinal matrixes with a greater sensitivity than anatomical imaging and histology. Finally, we demonstrated CHP's binding to degenerated human discs, suggesting exciting potentials for applying CHP for diagnosing, monitoring, and treating various spinal disorders, including intervertebral disc degeneration, facet joint osteoarthritis, and ankylosing spondylitis.

BRD4 promotes heterotopic ossification through upregulation of LncRNA MANCR.

AIMS: Acquired heterotopic ossification (HO) is a debilitating disease characterized by abnormal extraskeletal bone formation within soft-tissues after injury. The exact pathogenesis of HO remains unknown. It was reported that BRD4 may contribute to osteoblastic differentiation. The current study aims to determine the role of BRD4 in the pathogenesis of HO and whether it could be a potential target for HO therapy. METHODS: Achilles tendon puncture (ATP) mouse model was performed on ten-week-old male C57BL/6J mice. One week after ATP procedure, the mice were given different treatments (e.g. JQ1, shMancr). Achilles tendon samples were collected five weeks after treatment for RNA-seq and real-time quantitative polymerase chain reaction (RT-qPCR) analysis; the legs were removed for micro-CT imaging and subsequent histology. Human bone marrow mesenchymal stem cells (hBMSCs) were isolated and purified bone marrow collected during surgeries by using density gradient centrifugation. After a series of interventions such as knockdown or overexpressing BRD4, Alizarin red staining, RT-qPCR, and Western Blot (Runx2, alkaline phosphatase (ALP), Osx) were performed on hBMSCs. RESULTS: Overexpression of BRD4 enhanced while inhibition of Brd4 suppressed the osteogenic differentiation of hBMSCs in vitro. Overexpression of Brd4 increased the expression of mitotically associated long non-coding RNA (Mancr). Downregulation of Mancr suppressed the osteoinductive effect of BRD4. In vivo, inhibition of BRD4 by JQ1 significantly attenuated pathological bone formation in the ATP model (p = 0.001). CONCLUSION: BRD4 was found to be upregulated in HO and Brd4-Mancr-Runx2 signalling was involved in the modulation of new bone formation in HO. Cite this article: Bone Joint Res 2021;10(10):668-676.

Comprehensive expression profiles of CircRNAs, LncRNAs, and mRNAs in PBMCs from patients with the ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL), one of spinal disease causing myelopathy, is characterized by the ectopic ossification and narrowing of the spinal cord. However, the pathogenesis of OPLL is largely unclear. In this study, transcriptome expression profiles (circRNAs, lncRNAs, and mRNAs) were identified via high-throughput sequencing using peripheral blood mononuclear cells (PBMCs) from OPLL and non-OPLL patients. We found that 1150 mRNAs, 331 circRNAs, and 1429 lncRNAs were significantly differentially expressed in the PBMCs of OPLL patients. GO and KEGG enrichment analyses revealed that most mRNAs were associated with inflammation. The co-expression networks indicated that circRNAs and lncRNAs could regulate the mRNAs through influencing the inflammation of OPLL. The circRNA-miRNA-mRNA integrated network showed that circRNA-regulated mRNAs associated with TGF-ß and TNF-α signaling pathways. These analyses indicate that circRNAs, lncRNAs, and mRNAs from PBMCs might contribute to inflammation in OPLL.

Aberrant upregulation of CaSR promotes pathological new bone formation in ankylosing spondylitis.

Pathological new bone formation is a typical pathological feature in ankylosing spondylitis (AS), and the underlying molecular mechanism remains elusive. Previous studies have shown that the calcium-sensing receptor (CaSR) is critical for osteogenic differentiation while also being highly involved in many inflammatory diseases. However, whether it plays a role in pathological new bone formation of AS has not been reported. Here, we report the first piece of evidence that expression of CaSR is aberrantly upregulated in entheseal tissues collected from AS patients and animal models with different hypothetical types of pathogenesis. Systemic inhibition of CaSR reduced the incidence of pathological new bone formation and the severity of the ankylosing phenotype in animal models. Activation of PLCγ signalling by CaSR promoted bone formation both in vitro and in vivo. In addition, various inflammatory cytokines induced upregulation of CaSR through NF-κB/p65 and JAK/Stat3 pathways in osteoblasts. These novel findings suggest that inflammation-induced aberrant upregulation of CaSR and activation of CaSR-PLCγ signalling in osteoblasts act as mediators of inflammation, affecting pathological new bone formation in AS.

The OLIF working corridor based on magnetic resonance imaging: a retrospective research.

OBJECTIVE: To provide an anatomical basis for the development of oblique lumbar interbody fusion (OLIF) in Chinese patients. METHODS: Between November 2018 and June 2019, 300 patients' lumbar MRI data were reviewed. According to the Moro system and zone method described by us, the axial view was vertically divided into 6 zones (A, I II, III, IV, P) and was horizontally divided into 4 zones (R, a, b, c, L). The locations of left psoas muscle and the major artery at L2/3, L3/4, and L4/5 levels were evaluated by the grid system. The aortic bifurcation segments will also be evaluated at the level of the vertebral body or the disc. RESULTS: At the L2/3 level, left psoas muscle and the major artery in zone Ib were found in 28.0% of subjects, in zone IIb in 20.3%, and in zone Ic in 20.0%; at the L3/4 level, in zone Ab in 20.7% of subjects, in zone Ac in 26.0%, and in zone Ic in 11.0%; and at the L4/5 level, areas in zone Ab in 31.0% of subjects, in zone Ac in 26.0%, and in zone Ib in 11.7%. The aortic bifurcation segments were mainly at the L4 level. The zone of the left psoas muscle at all levels, the zone of the major artery at L4/5 level, and the zone of the aortic bifurcation segments had significant correlation with gender difference (P < 0.05). CONCLUSION: The left-sided OLIF at L2-L5 disc levels can be a feasible type of surgery for lumbar interbody fusion in the majority of Chinese patients. Before the operation, in order to screen out the appropriate surgical approach, routine lumbar magnetic resonance imaging is recommended to analyze the patient's local anatomical features.

TNF-α/STAT3 pathway epigenetically upregulates Nav1.6 expression in DRG and contributes to neuropathic pain induced by L5-VRT.

BACKGROUND: Studies showed that upregulation of Nav1.6 increased the neuronal excitability and participated in neuropathic pain in the dorsal root ganglion (DRG). However, the molecular mechanisms underlying Nav1.6 upregulation were not reported yet. METHODS: The paw withdrawal threshold was measured in the rodents following lumbar 5 ventral root transection (L5-VRT). Then qPCR, western blotting, immunoprecipitation, immunohistochemistry, and chromatin immunoprecipitation assays were performed to explore the molecular mechanisms in vivo and in vitro. RESULTS: We found that the levels of Nav1.6 and phosphorylated STAT3 were significantly increased in DRG neurons following L5-VRT, and TNF-α incubation also upregulated the Nav1.6 expression in cultured DRG neurons. Furthermore, immunoprecipitation and chromatin immunoprecipitation assays demonstrated that L5-VRT increased the binding of STAT3 to the Scn8a (encoding Nav1.6) promoter and the interaction between STAT3 and p300, which contributed to the enhanced transcription of Scn8a by increasing histone H4 acetylation in Scn8a promoter in DRG. Importantly, intraperitoneal injection of the TNF-α inhibitor thalidomide reduced the phosphorylation of STAT3 and decreased the recruitment of STAT3 and histone H4 hyperacetylation in the Scn8a promoter, thus subsequently attenuating Nav1.6 upregulation in DRG neurons and mechanical allodynia induced by L5-VRT. CONCLUSION: These results suggested a new mechanism for Nav1.6 upregulation involving TNF-α/STAT3 pathway activation and subsequent STAT3-mediated histone H4 hyperacetylation in the Scn8a promoter region in DRG, which contributed to L5-VRT-induced neuropathic pain.

Increased survival of patients aged 0-29 years with osteosarcoma: A period analysis, 1984-2013.

PURPOSE: Osteosarcoma is the most common primary malignancy of bone, and typically occurs among children and adolescence. This study aims to evaluate treatment outcomes among children, adolescents and young adults with osteosarcoma over the three decades by the changes in the long-term relative survival. METHODS: Osteosarcoma incidence and relative survival data from Surveillance, Epidemiology, and End Results (SEER) registries during 1984-2013 were analyzed. The survival differences over three decades, age, sex, race, and socioeconomic status (SES) were assessed by comparing Kaplan-Meier curves. RESULTS: The overall incidence of osteosarcoma kept relatively stable with 0.4 per 100 000 in the three decades with the peak incidence occurring in the aged 10-19 group. The 10-year relative survival rate (RSR) increased from 57.7% to 61.0% in the three decades, with the greatest increase in the aged 0-9 group from 48.2% to 65.7%. The 10-year RSR improved from 54.1% to 61.5% in males, and from 62.4% to 63.0% in females, respectively, in the three decades. Furthermore, survival dramatically improved from 30% to 60% in the high-poverty group over the three decades. CONCLUSION: This study demonstrated that the overall incidence of osteosarcoma remained stable, with an improvement in survival in the three decades. The improved survival was greater in males than in females in the three decades. Furthermore, the survival significantly increased in high-poverty group, which was attributed to increasing improved health care system and patients with low finance can also have access to receiving effective and consistent treatment without distinction.

Epigenetic upregulation of CXCL12 expression contributes to the acquisition and maintenance of morphine-induced conditioned place preference.

Addiction and rewarding effect is a primary side effect of morphine, which is commonly used to relieve the acute or chronic pain. Several lines of evidence have suggested that inflammation response in the VTA contributes to morphine-induced reward (conditioned place preference, CPP), while the mechanism are poorly understood. The present study showed that repeated morphine conditioning persistently increased the expression of CXCL12 mRNA and protein in VTA. Furthermore, inhibition of CXCL12 prevented the acquisition and maintenance, but not the expression, of morphine-induced CPP in rodent. In addition, molecular analysis revealed that morphine conditioning increased the occupancy of p-STAT3 in the specific binding site (-1667/-1685) of CXCL12 promoter regions, and enhanced the interaction between acetyltransferase p300 and STAT3, and, hence, induced the histone H4 hyperacetylation in the promoter region and facilitated the transcription and expression of CXCL12 in VTA. Collectively, these results, for the first time, provided the evidence that persisted increase of VTA CXCL12 via epigenetic mechanism mediated the acquisition and maintenance, but not the expression, of morphine CPP.

Inflammation Intensity-Dependent Expression of Osteoinductive Wnt Proteins Is Critical for Ectopic New Bone Formation in Ankylosing Spondylitis.

OBJECTIVE: To investigate the molecular mechanism underlying inflammation-related ectopic new bone formation in ankylosing spondylitis (AS). METHODS: Spinal tissues and sera were collected from patients with AS and healthy volunteers and examined for the expression of Wnt proteins. An in vitro cell culture system mimicking the local inflammatory microenvironment of bone-forming sites was established to study the relationship between inflammation and Wnt expression, the regulatory mechanism of inflammation-induced Wnt expression, and the role of Wnt signaling in new bone formation. Modified collagen-induced arthritis (CIA) and proteoglycan-induced spondylitis (PGIS) animal models were used to confirm the key findings in vivo. RESULTS: The levels of osteoinductive Wnt proteins were increased in sera and spinal ligament tissues from patients with AS. Constitutive low-intensity tumor necrosis factor (TNF) stimulation, but not short-term or high-intensity TNF stimulation, induced persistent expression of osteoinductive Wnt proteins and subsequent bone formation through NF-κB (p65) and JNK/activator protein 1 (c-Jun) signaling pathways. Furthermore, inhibition of either the Wnt/ß-catenin or Wnt/protein kinase Cδ (PKCδ) pathway significantly suppressed new bone formation. The increased expression of Wnt proteins was confirmed in both the modified CIA and PGIS models. A kyphotic and ankylosing phenotype of the spine was seen during long-term observation in the modified CIA model. Inhibition of either the Wnt/ß-catenin or Wnt/PKCδ signaling pathway significantly reduced the incidence and severity of this phenotype. CONCLUSION: Inflammation intensity-dependent expression of osteoinductive Wnt proteins is a key link between inflammation and ectopic new bone formation in AS. Activation of both the canonical Wnt/ß-catenin and noncanonical Wnt/PKCδ pathways is required for inflammation-induced new bone formation.

[Comparative study of decompression and non-decompression surgeries in treatment of thoracolumbar fractures with intraspinal occupying and without neurological symptoms].

Objective: To investigate the effectiveness of posterior non-decompression surgery in the treatment of thoracolumbar fractures without neurological symptoms by comparing with the conventional posterior decompression surgery. Methods: Between October 2008 and October 2015, a total of 97 patients with thoracolumbar fractures with intraspinal occupying 1/3-1/2 and without neurological symptoms were divided into the decompression surgery group (51 cases) and the non-decompression surgery group (46 cases). There was no significant difference in gender, age, cause of injury, injury segment, the thoracolumbar injury severity score (TLICS), combined injury, disease duration, and preoperative relative anterior vertebral height, kyphosis Cobb angle, intraspinal occupying percentage, visual analogue scale (VAS), Oswestry disability index (ODI), and Japanese Orthopaedic Association (JOA) score between 2 groups ( P>0.05). The operation time, intraoperative blood loss volume, postoperative drainage, bed rest time, hospitalization time, and relative anterior vertebral height, kyphosis Cobb angle, intraspinal occupying percentage, and VAS score, ODI, JOA score at preoperative and postoperative 3 days and 1 year were recorded and compared. Results: The operation time, intraoperative blood loss volume, and postoperative drainage in non-decompression surgery group were significantly less than those in decompression surgery group ( P<0.05). There was no significant difference in the postoperative bed rest time and hospitalization time between 2 groups ( P>0.05). In decompression surgery group, 4 cases had cerebrospinal fluid leakage and healed after conservative treatment. All incisions healed by first intention, and no nerve injury or infection of incision occurred. All patients were followed up 10-18 months (mean, 11.7 months). The recovery of vertebral body height was satisfactory in 2 groups, without secondary kyphosis and secondary nerve symptoms. The imaging indexes and effectiveness scores of 2 groups at 3 days and 1 year after operation were significantly improved when compared with preoperative ones ( P<0.05). The intraspinal occupying percentage, VAS score, and ODI at 1 year after operation were significantly lower than those at 3 days after operation in 2 groups ( P<0.05), and JOA score at 1 year after operation was significantly higher than that at 3 days after operation ( P<0.05). Relative anterior vertebral height at 1 year after operation was significantly higher than that at 3 days after operation in non-decompression surgery group ( P<0.05); and there was no significant difference in decompression surgery group ( P>0.05). At 3 days, the intraspinal occupying percentage and JOA score in non-decompression surgery group were higher than those in decompression surgery group ( P<0.05), and VAS score and ODI at 3 days in non-decompression surgery group were lower than those in decompression surgery group ( P<0.05). No significant difference was found in the other indexes between 2 groups at 3 days and 1 year after operation ( P>0.05). Conclusion: Compared with the posterior decompression surgery, posterior non-decompression surgery has the advantages of less bleeding, less trauma, less postoperative pain, and so on. It is an ideal choice for the treatment of thoracolumbar fractures with intraspinal occupying 1/3-1/2 and without neurological symptoms under the condition of strict indication of operation.

Hypoxia suppresses serum deprivation-induced degradation of the nucleus pulposus cell extracellular matrix through the JNK and NF-κB pathways.

Intervertebral disc (IVD) degeneration is associated with the imbalance between anabolism and catabolism of the nucleus pulposus (NP) extracellular matrix (ECM). Serum deprivation (SD) has been reported to exacerbate IVD degeneration; however, the effect of SD on ECM metabolism is not fully understood. Hypoxia plays important roles in maintaining the physiological functions of IVD cells; however, whether hypoxia has any effect on NP ECM production under conditions of SD is still unclear. In the current study, we established an in vitro SD model by exposing NP cells to serum-free medium. SD decreased the expression of aggrecan and collagen II, as well as the production of sulfated glycosaminoglycan (sGAG) in a time-dependent manner. However, hypoxia abolished SD-mediated down-regulation of aggrecan and collagen II expression via JNK1/2 activation. Moreover, hypoxia abolished SD-induced MMP-3 and MMP-13 expression by inhibiting NF-κB activation, p65 translocation, and MMP-3 and MMP-13 promoter activity. These results indicated that, hypoxia maintained ECM production under conditions of SD. This effect was elicited in part through JNK1/2-mediated up-regulation of matrix gene expression and down-regulation of MMP expression, through the inhibition of NF-κB. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2059-2066, 2017.

Low back pain associated with lumbar disc herniation: role of moderately degenerative disc and annulus fibrous tears.

Lumbar disc herniation is one of the most common spinal degenerative disorders which may lead to low back pain (LBP) and radicular leg pain. However, it remains difficult to diagnose a degenerative herniated disc as the LBP generator in clinical practice. The purpose of this study is to explore the characteristic changes of a herniated disc causing LBP on MRI and to clarify the underlying role of inflammatory mediators and annulus fibrous (AF) tears in LBP generation associated with disc herniation. We prospectively collected intervertebral disc specimens and MRI from 57 single-segment disc herniation patients with radiculopathy. All subjects were grouped according to LBP occurrence or disc degeneration severity for the comparison of inflammatory mediators' expression and AF tears occurrence (High Intensity Zone, HIZ, on MRI). LBP incidence under circumstances of different degeneration severity with or without HIZ was further analyzed. Both LBP incidence and Inflammatory mediators expression in moderately degenerated group was higher than mildly and severely degenerative groups. HIZ incidence was higher in moderately and severely degenerated groups. LBP incidence in the patients with both moderately degenerated discs and HIZ was 86.7%, much higher than the rest of the patient population. In conclusion, the high expression of inflammatory mediators with AF tears causes LBP associated with disc herniation. Moderately degenerative disc with HIZ is MRI morphological change of herniated disc causing LBP, which can be applied to diagnose LBP.

LIM Mineralization Protein-1 Enhances Bone Morphogenetic Protein-2-Mediated Osteogenesis Through Activation of ERK1/2 MAPK Pathway and Upregulation of Runx2 Transactivity.

LIM mineralization protein-1 (LMP-1) is an intracellular regulator of bone formation. Upregulation of bone morphogenetic proteins (BMPs) and stabilization of BMP/Smad signaling have been proven to be the key mechanisms through which LMP-1 enhances osteogenesis. However, how LMP-1 regulates BMPs expression and related bone formation remains unclear. In this study, a LMP-1-induced osteogenesis cell model was used to study the molecular action of LMP-1 on BMP-2 expression and bone formation. The results show that overexpression of LMP-1 significantly increases, whereas downregulation of endogenous LMP-1 decreases BMP-2 expression and bone formation. Antagonism of BMP-2 with noggin or short hairpin BMP-2 significantly attenuates the osteoinductive effect of LMP-1, suggesting that the osteoinductive effect of LMP-1 is mediated by BMP-2. LMP-1 regulation of BMP-2 is found to occur at the transcription level using a luciferase reporter assay with a reporter construct containing a BMP-2 promoter. A promoter deletion assay reveals that -1000/-500 bp is the key regulated region by LMP-1. A Runx2-binding site is then located at -934/-920 bp and confirmed by luciferase assay using a reporter construct containing repeats of this Runx2-binding site and the site-directed mutagenesis analysis. Overexpression of LMP-1 significantly increases Runx2 expression. Downregulation of Runx2 expression significantly decreases BMP-2 promoter activity and BMP-2 expression. A ChIP assay demonstrates that LMP-1 increases the interaction between Runx2 and BMP-2 promoter. A luciferase reporter assay using the OSE2 promoter containing a Runx2-binding site confirms that Runx2 transactivity can be upregulated by LMP-1. Moreover, inhibiting the activation of different pathways with specific pathway inhibitors reveals that ERK1/2 MAPK activation is essential for LMP-1-induced upregulation of Runx2 transactivity and subsequent BMP-2 expression. In conclusion, our novel findings describe a positive regulatory effect of LMP-1 on BMP-2 expression and BMP-2-mediated osteogenesis. This effect occurs through activation of ERK1/2 pathway and subsequent upregulation of Runx2 transactivity.

Reducing radiation exposure during kyphoplasty with the use of a remote control injection system: a prospective study.

STUDY DESIGN: A prospective study. OBJECTIVE: To compare surgeons' radiation exposure during kyphoplasty with and without the use of a remote control injection system. SUMMARY OF BACKGROUND DATA: Distance from radiation sources is a critical factor for reducing radiation exposure during spine surgery. A newly designed device was used to minimize operators' radiation exposure during kyphoplasty. METHODS: Forty-four patients admitted for single-level osteoporotic vertebral compression fracture were randomly divided into 2 groups (groups A and B) and treated with kyphoplasty. The remote control injection system was used only in group B. The radiation doses to the surgeon's eyes, thyroid, chest, and right wrist were recorded with 4 unprotected radiometers simultaneously. Operation time, fluoroscopic time, cement amount, patient-reported pre- and postoperative visual analogue scale scores for pain, and complications were recorded. RESULTS: For group A, the radiation doses at the eyes, thyroid, and right wrist were 1.132 ± 0.104 mSv, 0.647 ± 0.049 mSv, 0.578 ± 0.056 mSv, and 1.877 ± 0.214 mSv, respectively; for Group B, these doses were 0.257 ± 0.067 mSv, 0.201 ± 0.049 mSv, 0.145 ± 0.033 mSv, and 0.353 ± 0.046 mSv, respectively (P < 0.05). Comparisons of the radiation doses the chief surgeon and the resident surgeon received showed that the resident surgeon received more radiation during group A procedures; during group B procedures, the surgeons received similar doses. The proportion of average fluoroscopic time devoted to the bone cement injection step for groups A and B was 64% and 63%, respectively, and the average proportion of the radiation doses that were received during the bone cement injection step was 66% for group A and 36% for group B. Compared with the preoperative visual analogue scale score, the postoperative visual analogue scale score was significantly reduced in both groups. CONCLUSION: During kyphoplasty, the use of the remote control injection system can significantly reduce surgeons' radiation exposure without affecting the efficiency of procedures.

LIM mineralization protein-1 suppresses TNF-α induced intervertebral disc degeneration by maintaining nucleus pulposus extracellular matrix production and inhibiting matrix metalloproteinases expression.

Imbalanced metabolism of Nucleus pulposus (NP) extracellular matrix (ECM) is closely correlated to Intervertebral Disc Degenerative Disease. LIM mineralization protein-1 (LMP-1) has been proven to induce sulfated glycosaminoglycan (sGAG) production in NP and have an anti-inflammatory effect in pre-osteoclast. However, whether it has any effect on the NP ECM production and degradation under inflammatory stimulation has not been studied. In the current study, a TNF-α induced cell model was established in vitro. Lentivirus encoding LMP-1 (LV-LMP-1) and short heparin LMP-1 (LV-shLMP-1) were constructed to overexpress and knockdown LMP-1 expression in NP cells. LMP-1 mRNA level was regulated in a dose-dependent manner after transfection. LV-LMP-1 increased whereas LV-shLMP-1 decreased collagen II, aggrecan, versican expression, and sGAG production. LV-LMP-1 abolished while LV-shLMP-1 aggravated TNF-α mediated down-regulation of the above matrix genes via ERK1/2 activation. Moreover, LV-LMP-1 abrogated TNF-α induced MMP-3 and MMP-13 expression via inhibiting p65 translocation and MMP-3 and MMP-13 promoter activity. These results indicated that LMP-1 had an ECM production maintenance effect under inflammatory stimulation. This effect was via up-regulation of matrix genes expression at least partially through ERK1/2 activation, and down-regulation of MMPs expression through NF-κB inhibition.

Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration.

OBJECT: The aim of this study was to evaluate the effects of rod stiffness and implant density on coronal and sagittal plane correction in patients with main thoracic curve adolescent idiopathic scoliosis (AIS). METHODS: The authors conducted a retrospective study of 77 consecutive cases involving 56 female and 21 male patients with Lenke Type 1 main thoracic curve AIS who underwent single-stage posterior correction and instrumented spinal fusion with pedicle screw fixation between July 2009 and July 2012. The patients' mean age at surgery was 15.79 ± 3.21 years. All patients had at least 1 year of follow-up. Radiological parameters in the coronal and sagittal planes, including Cobb angle of the major curve, side-bending Cobb angle of the major curve, thoracic kyphosis (TK), correction rates, and screw density, were measured and analyzed. Screw densities (calculated as number of screws per fusion segment × 2) of < 0.60 and ≥ 0.60 were defined as low and high density, respectively. Titanium rods of 5.5 mm and 6.35 mm diameter were defined as low and high stiffness, respectively. Patients were divided into 4 groups based on the type of rod and density of screw placement that had been used: Group A, low-stiffness rod with low density of screw placement; Group B, low-stiffness rod with high density of screw placement; Group C, high-stiffness rod with low density of screw placement; Group D, high-stiffness rod with high density of screw placement. RESULTS: The mean coronal correction rate of the major curve, for all 77 patients, was (81.45% ± 7.51%), and no significant difference was found among the 4 groups (p > 0.05). Regarding sagittal plane correction, Group A showed a significant decrease in TK after surgery (p < 0.05), while Group D showed a significant increase (p < 0.05); Group B and C showed no significant postoperative changes in TK (p > 0.05). The TK restoration rate was highest in Group D and lowest in Group A (A, -39.32% ± 7.65%; B, -0.37% ± 8.25%; C, -4.04% ± 6.77%; D, 37.59% ± 8.53%). Screw density on the concave side was significantly higher than that on the convex side in all the groups (p < 0.05). CONCLUSIONS: For flexible main thoracic curve AIS, both rods with high stiffness and those with low stiffness combined with high or low screw density could provide effective correction in the coronal plane; rods with high stiffness along with high screw density on the concave side could provide better outcome with respect to sagittal TK restoration.

Both expression of cytokines and posterior annulus fibrosus rupture are essential for pain behavior changes induced by degenerative intervertebral disc: An experimental study in rats.

The aim of this study was to analyze the relationship between intervertebral disc degeneration and low back pain (LBP). Rat L4/5 disc degeneration model was established by annular puncture using a 0.4 mm needle anteriorly or posteriorly. In both anterior and posterior puncture models, magnetic resonance imaging (MRI) and histological analyses revealed marked disc degeneration 2 weeks after puncture. Cytokine expression was up-regulated in different level in nucleus pulposus (NP) from 3 days after puncture. Pain behavioral tests indicated that the anterior disc puncture did not induce pain behavior changes, whereas the posterior disc puncture resulted in mechanical allodynia from 1 day to 21 days after injury. Besides, cytokine expression was significantly increased in dorsal root ganglion (DRG) at 1 and 2 weeks after posterior puncture, but not after the anterior puncture. These findings indicate the NP of the degenerative disc expresses different levels of inflammatory cytokines, and posterior disc puncture produced mechanical allodynia. The expression phase of cytokines in the NP was accordance with mechanical hyperalgesia in the posterior disc puncture model. Both expression of cytokines and posterior annulus fibrosus (AF) rupture in degenerative intervertebral disc are essential for pain behavior changes.