Gengting Dang

Simvastatin induces osteoblastic differentiation and inhibits adipocytic differentiation in mouse bone marrow stromal cells

To clarify the mechanism of the stimulatory effect of statins on bone formation, we investigated the effect of simvastatin, a widely used statin, on osteoblastic and adipocytic differentiation in primary cultured mouse bone marrow stromal cells (BMSCs). Simvastatin treatment enhanced the expression level of mRNA for osteocalcin and protein for osteocalcin and osteopontin, and increased alkaline phosphatase activity significantly (p<0.05). After BMSCs were exposed to an adipocyte differentiation agonist, Oil Red O staining, fluorescence activated cell sorting, and decreased expression level of lipoprotein lipase mRNA showed that treatment with simvastatin significantly inhibits adipocytic differentiation compared to controls that did not receive simvastatin (p<0.05). Lastly, we found that simvastatin induces high expression of BMP(2) in BMSCs. These observations suggested that simvastatin acts on BMSCs to enhance osteoblastic differentiation and inhibits adipocytic differentiation; this effect is at least partially mediated by inducing BMP(2) expression in BMSCs.

Cbfa1/osf2 Transduced Bone Marrow Stromal Cells Facilitate Bone Formation In Vitro and In Vivo

It has been well established that core binding factor a-1/osteoblast-specific factor-2 (cbfa1/osf2) is a key regulator of osteoblast differentiation and function, however, it is not known whether it can induce bone formation in vitro and in vivo. To investigate the effect of cbfa1/osf2 on bone formation, we used a recombinant adenoviral vector carrying the mouse cbfa1/osf2 gene to transduce primary cultured bone marrow stromal cells (MSCs) of BALB/c mice. We found that Ad-cbfa1/osf2-transduced MSCs produced cbfa1/osf2 protein and differentiated into osteoblast-like cells. The transduced MSCs had increased alkaline phosphatase activity, increased expression of osteocalcin, osteopontin and bone sialoprotein, and increased matrix mineralization in vitro. To observe the induction of bone formation in vivo, MSCs transduced with Ad-cbfa1/osf2 were transplanted into a 5 mm diameter critical-sized skull defect in BALB/c mice, with type I collagen as scaffolding material. Healing of the defect in treatment and control groups was examined grossly and histologically at four weeks. Skull defects transplanted with Ad-cbfa1/osf2-transduced MSCs had an average of 85% osseous closure at four weeks. Control groups in which the defects were not treated (group 1), treated with collagen only (group 2), or treated with collagen and nontransduced MSCs (group 3) showed little or no osseous healing. These studies indicate that cbfa1/osf2 can induce osteoblast differentiation and bone formation both in vitro and in vivo, suggesting that MSCs transduced with the cbfa1/osf2 gene may be useful in treating bone defects.

Simvastatin treatment improves functional recovery after experimental spinal cord injury by upregulating the expression of BDNF and GDNF

The aim of this study was to determine the therapeutic efficacy of simvastatin treatment starting 1 day after spinal cord injury (SCI) in rat and to investigate the underlying mechanism. Spinal cord injury was induced in adult female Sprague-Dawley rats after laminectomy at T9-T10. Then additionally with sham group (laminectomy only) the SCI animals were randomly divided into 3 groups: vehicle-treated group; 5-mg/kg simvastatin-treated group; and 10-mg/kg simvastatin-treated group. Simvastatin or vehicle was administered orally at 1 day after SCI and then daily for 5 weeks. Locomotor functional recovery was assessed during 8 weeks postoperation by performing open-field locomotor test and inclined-plane test. At the end of study, motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs) were assessed to evaluate the integrity of spinal cord pathways. Then, the animals were killed, and 1-cm segments of spinal cord encompassing the injury site were removed for histopathological analysis. Immunohistochemistry was performed to observe the expression of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) in the spinal cord. Results show that the simvastatin-treated animals showed significantly better locomotor function recovery, better electrophysiological outcome, less myelin loss, and higher expression of BDNF and GDNF. These findings suggest that simvastatin treatment starting 1 day after SCI can significantly improve locomotor recovery, and this neuroprotective effect may be related to the upregulation of BDNF and GDNF. Therefore, simvastatin may be useful as a promising therapeutic agent for SCI.

Interferon alfa-2b for recurrent and metastatic giant cell tumor of the spine: report of two cases.

Study Design. Case report. Objective. To demonstrate that interferon alfa-2b is a therapeutic option for obtaining long-term control of recurrent and metastatic giant cell tumor of spine. Summary of Background Data. Interferon alfa served as angiogenesis inhibitor and has been successfully used to treat giant cell tumor of long bones and facial bones. Up to date, no report is found with regard to the use of interferon as a stand-alone treatment for unresectable, recurrent, and metastatic giant cell tumor originated from the spine. Methods. A 29-year-old woman with C1 and C2 giant cell tumor was treated by radiotherapy, intralesional curet, and chemotherapy orderly. Tumor recurred after 2 years. A second curet was undertaken. Tumor recurred second time and caused severe spinal cord compression. Lung metastasis was diagnosed simultaneously. A 24-year-old man with recurrent giant cell tumor of T5 and T6 was treated by spondylectomy of T5 and T6. Six months later, a giant metastatic lesion was found in sacrococcygeal region, which was excised and proved to be giant cell tumor of bone. Four months later, 2 recurrent lesions were found beside the rectum. Interferon alfa-2b at a dose of 3,000,000 U/m2 was then administered subcutaneously everyday for both patients for 3.5 and 3 years, respectively. Results. No major complications related to the use of interferon occurred. The lesion in C1-C2 of the first patient regressed steadily and was restricted and encircled within the lateral mass. The metastatic lesions in the lungs also significantly reduced. The pararectal lesions of the second patient disappeared completely. Conclusion. Interferon therapy may be an effective and safe treatment for spine giant cell tumor recurrence and metastasis in soft tissue. The effectiveness may be time and dosage dependent.

Simvastatin mobilizes bone marrow stromal cells migrating to injured areas and promotes functional recovery after spinal cord injury in the rat

This study investigated the therapeutic effects of simvastatin administered by subarachnoid injection after spinal cord injury (SCI) in rats; explored the underlying mechanism from the perspective of mobilization, migration and homing of bone marrow stromal cells (BMSCs) to the injured area induced by simvastatin. Green fluorescence protein labeled-bone marrow stromal cells (GFP-BMSCs) were transplanted into rats through the tail vein for stem cell tracing. Twenty-four hours after transplantation, spinal cord injury (SCI) was produced using weight-drop method (10g 4cm) at the T10 level. Simvastatin (5mg/kg) or vehicle was administered by subarachnoid injection at lumbar level 4 after SCI. Locomotor functional recovery was assessed in the 4 weeks following surgery using the open-field test and inclined-plane test. At the end of the study, MRI was used to evaluate the reparation of the injured spinal cord. Animals were then euthanized, histological evaluation was used to measure lesion cavity volumes. Immunofluorescence for GFP and cell lineage markers (NeuN and GFAP) was used to evaluate simvastatin-mediated mobilization and differentiation of transplanted BMSCs. Western blot and immunohistochemistry were used to assess the expression of vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF). Simvastatin-treated animals showed significantly better locomotor recovery, less signal abnormality in MRI and a smaller cavity volume compared to the control group. Immunofluorescence revealed that simvastatin increased the number of GFP-positive cells in the injured spinal cord, and the number of cells double positive for GFP/NeuN or GFP/GFAP was larger in the simvastatin treated group than the control group. Western blot and immunohistochemistry showed higher expression of BDNF and VEGF in the simvastatin treated group than the control group. In conclusion, simvastatin can help to repair spinal cord injury in rat, where the underlying mechanism appears to involve the mobilization of bone marrow stromal cells to the injured area and higher expression of BNDF and VEGF.

Hyaluronan tetrasaccharide in the cerebrospinal fluid is associated with self-repair of rats after chronic spinal cord compression

The objective of this study was to explore changes in hyaluronan levels in the cerebrospinal fluid (CSF) in a spinal cord compression model, to investigate whether hyaluronan tetrasaccharide was involved in this process, and to test the effects of hyaluronan tetrasaccharide on neuron and oligodendrocyte repair. We developed a chronic spinal cord compression model with various sizes of polymer sheets (1.5×0.7×0.3 mm(3); 5×1.5×0.7 mm(3)) that were implanted microsurgically underneath the C(5-6) laminae. The rats were divided into three groups: a sham group, a mildly compressed (MC) group, and a widely compressed (WC) group. Locomotor functional evaluations revealed that the behavioral function of the MC and WC groups dropped to their lowest level from the fourth to fifth week and gradually recovered thereafter. The hyaluronan levels in the CSF gradually increased after spinal cord compression. Furthermore, hyaluronan tetrasaccharide was involved in the hyaluronan change. In addition, we found that nuclear factor kappa B (NF-κB) and cellular inhibitor-of-apoptosis protein 2 (c-IAP(2)) were co-expressed in neurons and oligodendrocytes, and caspase-3 expression gradually decreased in the compression model. The brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) expression was upregulated in astrocytes at the fourth week post-compression. Hyaluronan tetrasaccharide (HA(4)) induced NF-κB and c-IAP(2) to suppress the H(2)O(2)-induced apoptosis in primary neuronal cultures and increased BDNF and VEGF expression in astrocytic cultures in vitro. These findings suggest that HA(4) in the CSF may associate with behavioral recovery by increasing the levels of NF-κB, c-IAP(2), and neurotrophic factors after chronic spinal cord compression.

Differential proteomic profiling of chordomas and analysis of prognostic factors

The recurrence rate of chordoma is high, and the prognosis is poor.

Simvastatin induces estrogen receptor-alpha (ER-α) in murine bone marrow stromal cells

Simvastatin has been shown to stimulate osteogenesis both in vitro and in vivo. However, the mechanism by which simvastatin exerts its effects is still unclear. We previously reported that simvastatin promotes bone morphogenetic protein 2 (BMP-2) expression, induces osteoblastic differentiation, and inhibits adipocytic differentiation in mouse bone marrow stromal cells (BMSCs), and that this occurs, at least in part, via a BMP-2-dependent pathway. The aim of this study was to investigate further the mechanisms by which simvastatin stimulates osteogenesis in mouse BMSCs. To determine whether simvastatin-mediated osteogenesis was dependent on BMP-2, mouse BMSCs were treated with nonimmune normal mouse IgG or BMP-2 neutralizing antibodies combined with different concentrations of simvastatin. Surprisingly, the stimulatory effect of simvastatin on alkaline phosphatase (ALP) activity was not completely blocked by neutralizing BMP-2 monoclonal antibody treatment. Interestingly, we found that estrogen receptor-alpha (ER-α) protein levels increased after mouse BMSCs were treated with simvastatin for 72 h in a concentration-dependent manner. Moreover, the stimulatory effect of simvastatin on ALP activity in BMSCs was blocked by the estrogen receptor agonist ICI 182,780, and cotreatment with 17-β-estradiol and simvastatin increased ALP activities by two-to threefold in the BMSCs compared with treatment with simvastatin alone. These results suggest that simvastatin-induced in vitro osteogenesis in mouse BMSCs is mediated, at least in part, by induction of ER-α and not by BMP-2 alone. These results provide new insight into the mechanisms of simvastatin-induced bone formation in BMSCs.

Stro‐1+ stromal cells have stem‐like features in giant cell tumor of bone

Giant cell tumor of bone (GCTB) is an aggressive benign bone tumor with poor prognosis whose neoplastic component is stromal cells (SCs). Tumor stem‐like cells (TSCs) have been demonstrated as precursors for tumor genesis and growth. The aim of this study is to identify TSCs in GCTB.

An Approach to Primary Tumors of the Upper Cervical Spine With Spondylectomy Using a Combined Approach: Our Experience with 19 Cases

Study Design. A retrospective study. Objective. To examine the link between major complications, surgical techniques, and perioperative care in the intralesional spondylectomy of the upper cervical spine. Summary of Background Data. Spondylectomy has been demonstrated to prolong cancer-free survival in many patients with locally aggressive spinal tumors. However, the challenging nature of this surgical procedure and the potential for severe complications often limit its application in the upper cervical spine. Methods. Nineteen patients with primary upper cervical tumors were treated with spondylectomy from March 2005 to August 2009, using either the anterior-posterior or posterior-anterior approach. Anterior procedures were transmandibular, transoral, or high retropharyngeal. Anterior reconstructions were performed in plates with iliac crest strut grafts, plates with mesh cages, and Harms mesh cages alone. Occipitocervical fixation was performed with Halo-vest application for postoperative immobilization. Results. Vertebral artery injuries occurred unilaterally in 5 cases intraoperatively: 4 occurred in the anterior approach of anterior-posterior procedures. Fusion was achieved in 9 patients with intact internal instrumentation. Fusion with the anterior construct in a tilted position occurred in 3 patients, all of whom underwent anterior-posterior procedures with Halo-vest immobilization for less than 1 month. Nonunion occurred in 3 cases after the posterior-anterior procedure because of anterior bone graft absorption. Prolonged Halo-vest immobilization maintained postoperative stability. Failure of internal instrumentation occurred in 3 cases. Anterior construct dislocation and severe tilting occurred in 2 cases after the anterior-posterior procedure. Five patients had a local recurrence. All recurrent lesions were malignant tumors and occurred in regions where surgical exposure was inadequate with incomplete excision. Conclusion. The order of the surgical approach is a critical determinant of complications, fusion rates, choice of surgical technique, and reconstruction methods. The postoperative use of a Halo-vest is recommended. Local recurrence is associated with tumor malignancy and inadequate excision margin. Level of Evidence: 4