Xintao Wang

SDF-1 promotes endochondral bone repair during fracture healing at the traumatic brain injury condition.

Purposes The objective of this study was to investigate the role of stromal cell-derived factor-1 (SDF-1) and its receptor, CXCR4, on bone healing and whether SDF-1 contributes to accelerating bone repair in traumatic brain injury (TBI)/fracture model. Materials and Methods Real-time polymerase chain reaction and immunohistochemical analysis were used to detect the expression of SDF-1 during the repair of femoral bone in TBI/fracture model. The TBI/fracture model was treated with anti–SDF-1 neutralizing antibody or AMD3100, an antagonist for CXCR4, and evaluated by histomorphometry. In vitro and in vivo migration assays were used to evaluate the functional effect of SDF-1 on primary mesenchymal stem cells. Results The expression of SDF1 and CXCR4 messenger RNA was increased during the bone healing in TBI/fracture model but was less increased in fracture only model. High expression of SDF-1 protein was observed in the surrounding tissue of the damaged bone. Treated with anti–SDF-1 antibody or AMD3100 could inhibit new bone formation. SDF-1 increased mesenchymal stem cell chemotaxis in vitro in a dose-dependent manner. The in vivo migration study demonstrated that mesenchymal stem cells recruited by SDF-1 participate in endochondral bone repair. Conclusion The SDF-1/CXCR4 axis plays a crucial role in the accelerating fracture healing under the condition of TBI and contributes to endochondral bone repair.

Aggrecan variable number of tandem repeat polymorphism and lumbar disc degeneration: a meta-analysis.

Study Design. Data on the association between the ACAN (encoded for aggrecan core protein) variable number of tandem repeat (VNTR) polymorphism and lumbar disc degeneration are conflicting, so we performed a meta-analysis. Objective. Aggrecan is involved in the shock absorbing function of the lumbar disc; we performed a meta-analysis to assess the association between ACAN VNTR and lumbar degeneration. Summary of Background Data. To perform a meta-analysis, we searched for studies published until September 2012, using electronic databases (PubMed, EMBASE, and China National Knowledge Infrastructure). Eight studies involving 965 cases of lumbar disc degeneration and 982 control subjects were identified. Methods. Assessment for eligibility and extraction of data were performed by 2 independent investigators. We extracted allele frequency for each study. We calculated the pooled odds ratios (ORs) and 95% confidence intervals (CI) to assess the strength of the association between the ACAN VNTR polymorphism and lumbar disc degeneration risk. Results. Results from the allele model suggested an increased risk of lumbar disc degeneration for the shorter alleles carriers compared with the normal alleles and longer alleles (OR = 1.54, 95% CI: 1.04–2.30, P = 0.03). In subgroup analysis by ethnicity, significant increased risks were found among Asians with shorter alleles (OR=1.65, 95% CI: 1.17–2.33, P = 0.004). Conclusion. Our results suggest an increased risk of shorter alleles compared with normal alleles and longer alleles against lumbar disc degeneration among populations especially among Asian descent. Such association may not be statistically significant in European populations. Level of Evidence: N/A

Aquaporin 3 protects against lumbar intervertebral disc degeneration via the Wnt/β-catenin pathway

Previous studies have demonstrated that the expression of aquaporin 3 (AQP3), a water channel which promotes glycerol permeability and water transport across cell membranes, is reduced in degenerative lumbar intervertebral disc (IVD) tissues. However, the role of AQP3 in the pathogenesis of IVD degeneration has not recieved much scholarly attention. The objective of the present study was to investigate the effect of AQP3 on cell proliferation and extracellular matrix (ECM) degradation in human nucleus pulposus cells (hNPCs) using gain-of-function and loss-of-function experiments, and to determine whether Wnt/β-catenin signaling is involved in the effect of AQP3 on IVD degeneration. hNPCs were transfected with the AQP3-pcDNA3.1 plasmid or AQP3 siRNA to overexpress or suppress AQP3. An MTT assay was performed to determine cell proliferation, and we found that AQP3 promoted hNPC proliferation. The expression of aggrecan, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)4 and ADAMTS5 was detected using western blot analysis, to examine the effect of AQP3 on ECM degradation in hNPCs. The results revealed that AQP3 inhibited ECM degradation in hNPCs. In addition, we found that Wnt/β-catenin signaling was suppressed by AQP3. However, the effect of AQP3 on hNPC proliferation and ECM degradation was reversed by treatment with lithium chloride, a known activator of Wnt/β‑catenin signaling. In conclusion, using in vitro and in vivo tests, we have reported for the first time, to the best of our knowledge, that AQP3 exerts protective effects against IVD degeneration, and these are effected, at least partially, through the inhibition of Wnt/β-catenin signaling.

Contralateral neuropathology in dorsal root ganglia in a rat model of noncompressive disc herniation.

Some cases of lumbar disc herniation with contralateral radiculopathy have been reported. Many investigators explained this clinical syndrome from several aspects. However, to our best knowledge, there is no explanation on the basis of molecular changes in the contralateral dorsal root ganglia (DRG) until now. We firstly explored the expression of activating transcription factor 3 (ATF3, a marker of nerve injury), glial fibrillary acidic protein (GFAP, a marker of satellite cells activation) in bilateral L5 DRG and spinal cord using immunohistochemistry after nucleus pulposus (NP) application onto the left L5 DRG exposed by unilateral facetectomy. Immunoblotting was used to detect the expression of tumor necrosis factor-alpha (TNF-alpha) in bilateral L5 DRG. We tested that ATF3-immunoreactive (IR) neurons, GFAP-IR satellite cells and TNF-alpha expression in the contralateral DRG increased significantly after NP application. In the spinal cord, ATF3-IR motor neurons increased significantly after surgery, but GFAP-IR astrocytes were not significant. These results suggested that NP application on the unilateral DRG could induce nerve injury, satellite cells activation and upregulation of TNF-alpha expression in the contralateral DRG. In addition, our results indicated that motor neurons injury might play a significant role in contralateral changes.

Protective Effects of Modeled Superoxide Dismutase Coordination Compound (MSODa) Against Ischemia/Reperfusion Injury in Rat Skeletal Muscle

Background/Aim: Ischemia/reperfusion (I/R) injury of skeletal muscles is common pathophysiology during surgeries and the superoxide dismutase (SOD) plays a critical role in this process. SOD-modeled coordination compound (MSODa) may simulate the protective effects as SOD. Methods: Therefore, this study was designed to explore the protective effects and underlying mechanism of MSODa on malondialdehyde (MDA) and integrin-β2 (CD11b/CD18) in plasma, myeloperoxidase (MPO) and intercellular cell adhesion molecule-1 (ICAM-1) in tissue, and morphological changes before and after I/R injury. The rat model of I/R in hind limb was established and randomly divided into sham, ischemia, I/R, I/R-treated with saline, SOD, and MSODa, respectively. Results: These results showed that averaged values for MDA, MPO, CD11b/CD18, and ICAM-1 were significantly increased (P < 0.01 vs ischemia alone) in a time-dependent fashion along with marked tissue remodeling, such as abnormal arrangement of muscular fibers, interstitial edema, vasodilation with no-reflow, inflammatory cells adherent and infiltration, structural changes in mitochondrial, and decrease in glycogens as well. However, all parameter changes induced by I/R injury were reversed, at least partially, by MSODa and SOD treatments and intriguingly, the beneficial/protective effects of MSODa was superior to SOD with an early onset. Conclusion: This novel finding demonstrates that MSODa improves I/R injury of skeletal muscles due at least partially to inhibition of adherent molecule expression and reduction of oxygen free radical formation during I/R pathophysiological processes and this protective action of MSODa was superior to SOD, highlighting the bright future for MSODa in clinical management of tissue I/R injury.

A comparison of osteocyte bioactivity in fine particulate bone powder grafts vs larger bone grafts in a rat bone repair model.

The osteogenic potential for bone grafts is based on numbers and activities of cells that survive transplantation. In this study, we compared the bioactivity of osteocytes in 300-500 μm fine particulate bone powder grafts to 2 mm larger bone grafts in a rat radial defect model. Expression levels of bone morphogenetic protein-2 (BMP-2), transforming growth factor-beta 1 (TGF-β1), alkaline phosphatase (ALP), and collagen I were semi-quantified by both immunohistochemistry and RT-PCR at days 1 and 4, as well as weeks 1, 2, 4, 6 and 10 post-transplantation. Within two weeks post-transplantation, more cells stained positively for BMP-2, TGF-β1, ALP, and collagen I within the bone grafts and in the surrounding tissues in the group transplanted with the fine particulate bone powder grafts than in those with larger bone grafts (P<0.05). The mRNA levels of all four markers in the group transplanted with fine particulate bone powder graft peaked earlier and were expressed more highly than in the larger bone graft group, suggesting that fine particulate bone powder grafts provide more viable and active osteocytes to accelerate bone defect healing than larger bone grafts.

Development and performance analysis of Si-CaP/fine particulate bone powder combined grafts for bone regeneration.

BackgroundAlthough autogenous bone grafts as well as several bone graft substitute material have been used for some time, there is high demand for more efficient and less costly bone-substitute materials. Silicon-substituted calcium phosphates (Si-CaP) and fine particulate bone powder (FPBP) preparations have been previously shown to individually possess many of the required features of a bone graft substitute scaffold. However, when applied individually, these two materials fall short of an ideal substitute material. We investigated a new concept of combining Si-CaP with FPBP for improved performance in bone-repair.MethodsWe assessed Si-CaP/FPBP combined grafts in vitro, by measuring changes in pH, weight loss, water absorption and compressive strength over time.ResultsSi-CaP/FPBP combined grafts was found to produce conditions of alkaline pH levels compared to FPBP, and scaffold surface morphology conducive to bone cell adhesion, proliferation, differentiation, tissue growth and transport of nutrients, while maintaining elasticity and mechanical strength and degradation at a rate closer to osteogenesis.ConclusionSi-CaP/FPBP combined grafts was found to be superior to any of the two components individually.

Extensor Tendon Injury Due to Repetitive Wrist Dorsiflexion: Morphological Study of Extensor Retinaculum and Extensor Tendon

Most etiological studies of extensor tendon injury were based on the normal anatomy of extensor tendon and extensor retinaculum of the wrist. Further understanding of the morphological changes of the extensor tendon and extensor retinaculum during wrist dorsiflexion might contribute to improved and more accurate understanding of the etiology. The morphology of the extensor tendon of the mid-finger and the fourth compartment of the wrist extensor retinaculum was studied by sonography, and the anatomy was studied in 15 extremities from 11 young male cadavers. Compared with anatomical images, ultrasonography provides similar morphological observations of the extensor retinaculum of the wrist and extensor tendon. Ultrasonography findings revealed that as the dorsiflexion angle changed, the extensor retinaculum of the wrist formed different shaped trochleas. The trochlea guides the rotation of the extensor tendon at the wrist, but it does not form a sharp corner with the extensor tendon; thus, the extensor tendon is not compressed. As the dorsiflexion angle increased from 0° to 60°, the length of the trochlea gradually decreases. The shortening of the trochlea length will lead to a smaller frictional contact area between the extensor tendon and the extensor retinaculum. Consequently, the friction is centralized. During wrist dorsiflexion, the extensor retinaculum provides a trochlea for the extensor tendon. Extensor tendon injury of repetitive wrist dorsiflexion might be caused by centralized friction at the small contact area.

The influence of orthotopic paraspinal muscle-pediculated bone flaps on posterior spinal fusion in a canine model.

Study Design. An experimental animal study with randomized, control design was conducted using a dog model. Objective. To construct a novel posterior lumbar spine fusion model with orthotopic paraspinal muscle-pediculated bone flaps and to compare with the conventional posterolateral lumbar intertransverse process fusion. Summary of Background Data. Previous studies have demonstrated that paraspinal musculature provided important vascular ingrowth into the fusion mass. However, the blood supply of paraspinal muscles was still not sufficiently used in spinal fusion. In this study, we assessed the significant role of orthotopic paraspinal muscle-pediculated bone flaps in the healing of bone graft in spinal fusion. Methods. Thirty-two mongrel dogs were randomly assigned to 2 groups to undergo either posterior spinal fusion with orthotopic paraspinal muscle-pediculated bone flaps (treatment group) or posterolateral intertransverse process fusion (control group) at L5–L6 segment. All the fusions used an autologous bone graft obtained from bilateral posterior iliac crests. The animals were killed at 8 weeks or 16 weeks after surgery. The lumbar spines were evaluated by radiology, histology, and biomechanics. Results. Treatment groups showed an increasing trend on radiographic grades, manual palpation, and biomechanical stiffness compared with control groups at 8 and 16 weeks. Histologic analysis revealed that there was more mature woven bone in the treatment group than the controls at both points. At 8 weeks, the histologic fusion rate was 21.4% in the treatment group, 50% in the control group (P < 0.05); and at 16 weeks the fusion rate was 50% and 87.5% in the control group and the treatment group, respectively (P < 0.05). Conclusion. The use of orthotopic paraspinal musclepediculated bone flaps increased the rate and quality of fusion in the experimental spinal fusion model. This suggested that the novel posterior spinal fusion could be further developed for clinical application.

Osteoblast-oriented differentiation of BMSCs by co-culturing with composite scaffolds constructed using silicon-substituted calcium phosphate, autogenous fine particulate bone powder and alginate in vitro

Autogenous bone graft is the best for spinal fusion in clinics, however, lacking sources, bleeding and infection are limited its practice. Seeking alternative materials are urgent for orthopaedic surgeon. Here, we evaluated osteoblast-oriented differentiation of rabbit BMSCs by co-culturing with composite scaffolds constructed using silicon-substituted-CaP-fine particulate bone powder-alginate. Using CCk8-kit, biocompatibility was evaluated by testing BMSCs proliferation; morphology and survival of osteoblasts within scaffolds were observed using EM and HE staining; growth factors and related genes were detected using RT-PCR. HE staining showed spindle-shaped BMSCs after the 3rd passage; EM data showed that uneven surface and longitudinal section were observed with scattered distribution of 5-100 mm interspaces, which leave enough space for BMSCs adhesion and growth. Interestingly, at 14-day culture with HE staining, osteocytes within the scaffolds grew well with regular shape and integrate structure. RT-PCR results showed that expression levels of BMP2, TGF-b and COL-I, ALP, OPN were increased significantly and time-dependently. Collectively, all mentioned effects were more obvious in co-culture BMSCs with scaffolds than those with other components. Immunohistochemistry showed that positive OPN expression was detected at 7-day co-culturing BMSCs with scaffold, rather than other situations. These results suggest that composite scaffolds constructed with Si-CaP-fine particulate bone powder-alginate have a certain degree of biocompatibility and bioactivity to promote osteoblast-oriented BMSCs differentiation.Autogenous bone graft is the best for spinal fusion in clinics, however, lacking sources, bleeding and infection are limited its practice. Seeking alternative materials are urgent for orthopaedic surgeon. Here, we evaluated osteoblast-oriented differentiation of rabbit BMSCs by co-culturing with composite scaffolds constructed using silicon-substituted-CaP-fine particulate bone powder-alginate. Using CCk8-kit, biocompatibility was evaluated by testing BMSCs proliferation; morphology and survival of osteoblasts within scaffolds were observed using EM and HE staining; growth factors and related genes were detected using RT-PCR. HE staining showed spindle-shaped BMSCs after the 3rd passage; EM data showed that uneven surface and longitudinal section were observed with scattered distribution of 5-100 mm interspaces, which leave enough space for BMSCs adhesion and growth. Interestingly, at 14-day culture with HE staining, osteocytes within the scaffolds grew well with regular shape and integrate structure. RT-PCR results showed that expression levels of BMP2, TGF-b and COL-I, ALP, OPN were increased significantly and time-dependently. Collectively, all mentioned effects were more obvious in co-culture BMSCs with scaffolds than those with other components. Immunohistochemistry showed that positive OPN expression was detected at 7-day co-culturing BMSCs with scaffold, rather than other situations. These results suggest that composite scaffolds constructed with Si-CaP-fine particulate bone powder-alginate have a certain degree of biocompatibility and bioactivity to promote osteoblast-oriented BMSCs differentiation.