Anterior reduction and fusion for treatment of massive tear drop fracture of axis combining with inferior endplate serious traversed lesion: A retrospective study.

BACKGROUND: Tear drop fracture of axis represents a very small percentage of injuries of the cervical spine, but there is controversy about the treatment method for tear drop fracture of axis, especially when a large avulsed fragment is significant displacement, which combined with the inferior endplate serious traversed lesion of axis. OBJECTIVE: To evaluate the clinical outcome of anterior reduction, graft fusion of C2-3 and plate fixation in the management of massive tear drop fracture of axis combining with inferior endplate serious traversed lesion of axis. METHODS: There were 7 patients with a massive tear drop fracture of axis combining with inferior endplate serious traversed lesion. The avulsed ratio of inferior endplate of axis was 46.8 ± 13.4%, the average angle of rotation of the avulsed fragment was 30.4 ± 11.7, and the average displacement was 7.7 ± 2.8 mm. The posterior displacement of axis body was observed with three patients. All patients underwent anterior reduction, graft fusion of C2-3 and plate fixation with high anterior cervical retropharyngeal approach. The follow-up ranges from 2 years to 5 years. RESULTS: In all cases, tear drop fracture was reduced completely, avulsed fragment got bony healing, and bone graft achieved bony fusion at C2-3. There were no local angle deformity and rotated deformity in all patients, and there were normal physiological lordosis and good stabilization of upper cervical spine. The neurological function of one patient with American Spine Injury Association (ASIA) impairment scale type D was improved to type E postoperatively. Six patients without neurological lesion had no neurological syndrome after operation. CONCLUSIONS: Anterior surgical procedures would be an effective treatment of massive tear drop fracture of axis combining with inferior endplate serious traversed lesion. Complete reduction, sufficient stabilization and normal physiological lordosis of upper cervical spine could be achieved postoperatively.

Cells scaffold complex for Intervertebral disc Anulus Fibrosus tissue engineering: in vitro culture and product analysis.

The study was designed to investigate feasibility of tissue culture in vitro utilizing static culture method. Annulus fibrosus cells obtained from spine of rabbits were cultured. Results showed that fibrous tissue infiltration could be detected in shallow layer. With extended time, tissue infiltration depth increased, but there were still a large amount of holes in central part. Fibrous tissue infiltration was detected in the control side products and inner infiltration wasn't obvious. Hydroxyproline content of the control side products gradually increased with extended culture time. Hydroxyproline content of the control side products in the third and fourth month was significantly higher than that in the first month, but lower than those of the experimental side products and normal annulus fibrosus cells. DNA content of the control side products in the third and fourth month was significantly increased compared to the first month. DNA content of the control side products at each phase point was significantly lower than that of the experimental side and normal annulus fibrosus cells. Furthermore, there was lower expression levels of the type I, II collagen mRNA and protein in the experimental side scaffolds compared to the control side product. This study demonstrates the successful formation of Intervertebral disc Anulus Fibrosus in vitro by static culture method.

Incorporating strategy in hybrid surgery for continuous two-level cervical spondylosis from a biomechanical perspective.

BACKGROUND AND OBJECTIVE: Hybrid surgery, incorporating cervical disc replacement and anterior cervical discectomy and fusion, has shown good clinical results in the treatment of multilevel cervical spondylosis according to early follow-ups. This study investigated the surgical strategy of hybrid surgery for two-level cervical spondylosis by distinguishing the biomechanical characteristics with different incorporating modes. METHOD: A finite element model of a healthy cervical spine including C2-T1 was developed, and hybrid surgery was simulated by replacing at one level with Prestige-LP and fusion at another level with the anterior plate in C3-C5 (Hybrid-S1: replaced at C3-C4, Hybrid-S2: replaced at C4-C5), and in C4-C6 (Hybrid-M1: replaced at C4-C5, Hybrid-M2: replaced at C5-C6) and in C5-C7 (Hybrid-U1: replaced at C5-C6, Hybrid-U2: replaced at C6-C7). The motion of C2 vertebrae in flexion, extension, axial rotation, and lateral bending was imposed on all hybrid models following the displacement control testing protocol. RESULTS: The largest range of motion (ROM) in a healthy spine was observed at C5-C6, followed by C3-C4, C4-C5 and C6-C7. On average, the ROM at the replaced segment increased by 175.7%, 202.7%, 176.3%, 117.1%, 139.4%, and 236.0% in Hybrid-S1, Hybrid-S2, Hybrid-M1, Hybrid-M2, Hybrid-U1, and Hybrid-U2, respectively. The facet joint stress at the replaced segment increased by 186.9%, 124.4%, 111.1%, 60.3%, 62.7%, and 144.7%, and the adjacent intradiscal pressure (IDP) increased by 45.2%, 38.7%, 2.7%, 2.1%, 13.9%, and 20.1%. CONCLUSIONS: Incorporating mode in hybrid surgery affects cervical biomechanics. Hybrid surgery with replacement at a segment with a greater ROM and fusion at a segment with a lower ROM can results in fewer changes in terms of overall cervical stiffness, ROM at the operative level, facet joint stress, and adjacent IDP. In hybrid surgery, it is better to implement disc replacement at a level with a greater ROM and fusion of another segment.

The intermediate clinical outcome and its limitations of Bryan cervical arthroplasty for treatment of cervical disc herniation.

STUDY DESIGN: This is a prospective, consecutive series study to determine the role of the Bryan artificial cervical disc replacement to treat the isolated cervical disc herniation for Chinese patients. OBJECTIVE: To evaluate the intermediate clinical outcome and its limitations of Bryan cervical disc replacement in the management of isolated cervical disc herniation in Chinese patients. Observing neurological improvement and the radiographic finding. SUMMARY OF BACKGROUND DATA: Most people believe that anterior cervical fusion is a factor that shall not be ignored in adjacent segment degeneration. Artificial cervical disc replacement, as a nonfusion technique, may offer a solution to this problem. The clinical outcome of cervical arthroplasty in oriental patients is not often seen in English literature. The variation of anatomic index in Asian patients was also not considered enough. METHODS: There were consecutive series of 45 patients with cervical disc herniation. The herniated disc was located at C3-4 in 2 cases, at C4-5 in 8 cases, at C5-6 in 24 cases, at C6-7 in 5 cases, at C4-5, 5-6 in 2 cases, at C3,4, 5-6 in 1 cases, and at C 5-6, 6.7 in 3 cases. There were 19 patients with myelopathy and 26 patients with radiculopathy. A total of 51 sets of Bryan cervical disc prosthesis were implanted. The follow-up ranges from 24 to 70 months. The clinical symptom and the neurological function were evaluated. The level of stableness and mobility at the implanting location were observed on dynamic radiograph postoperatively. RESULTS: A total of 51 Bryan cervical disc prosthesis were implanted. Single-level disc was replaced in 39 cases whereas bilevel in 6 cases. The follow-up ranges from 24 to 70 months, with an average of 35 months. Patients showed significant improvement in neurological symptoms. The JOA score (17 points) was from 10.2 increased to 15.4 at final follow-up. The neck disability index was from 43.5 reduced to 28.4 at final follow-up. The clinical success (excellent/good/fair) according to Odom' Criteria were 89.8%. The average range of motion at implant level was 9.3 degrees, postoperatively. Migration of artificial disc greater than 2 mm was not observed. Resorption at the inferior edge of anterior surface of upper vertebral body were seen in 3 patients, Two patients had II grade heterotopic ossification. One patient had a definite spontaneous fusion of treated segment after 4 years of follow-up. There was some difficulty for exact matched implant in small group patients owing to the variation of anatomic index in oriental patients. CONCLUSIONS: Cervical arthroplasty had a good intermediate clinical outcome for oriental patients. Definite stabilization and satisfactory mobility were achieved after surgery, with significant neurological symptom improvement observed. For better matched implant, more shapes/sizes of artificial cervical disc need to be made available for the oriental patients.

[Clinical study on lumbar spondylolisthesis treated by minimally invasive transforaminal lumbar interbody fusion].

OBJECTIVES: To retrospectively analyze the treatment of lumbar spondylolisthesis using minimally invasive and open transforaminal lumbar interbody fusion (TLIF), and compare the clinical results of two techniques. METHODS: From June 2006 to May 2010, 371 patients with lumbar spondylolisthesis grade 1 and 2 were treated with TLIF, pedicle screw fixation and followed up. The mean age was 50.4 years (range, 37 - 85 years). There were 172 patients who underwent minimally invasive TLIF and percutaneous pedicle screw fixation were set as the MIS-TLIF group, 199 patients who underwent open TLIF and pedicle screw fixation were set as the OTLIF group. The operative time, blood loss, X-ray exposure time and complications were compared between the two groups. Clinical outcome was assessed using the visual analog scale (VAS) and the Oswestry disability index (ODI). Fusion rates were determined by using CT scan reconstruction and dynamic lumbar radiography in last fellow-up. RESULTS: The average follow-up duration was 32.7 months with a range of 12-58 months. The gender, age, classification of spondylolisthesis and level of fusion showed a identical pattern in both groups. The mean intra-operative blood loss (310 ± 75) ml and postoperative blood loss (38 ± 13) ml in MIS-TLIF group were significantly superior to the intra-operative blood loss (623 ± 156) ml and postoperative blood loss (184 ± 72) ml in OTLIF group (t = 2.836 and 3.274, P < 0.01). Comparing with the OTLIF group (20 ± 10) s, the MIS-TLIF group had a significantly longer radiation time (51 ± 19) s (t = 2.738, P < 0.01). There was no statistical difference in operating time, lower back pain VAS scores, ODI scores and incidence of complication between the two groups. CONCLUSIONS: Comparing with open TLIF, minimally invasive TLIF is a safe and reliable procedure for treatment of lumbar spondylolisthesis grade 1 and 2 with potential advantages.

Operative treatment for cervical fracture and dislocation with blunt unilateral vertebral artery injury.

OBJECTIVE: To investigate risks and clinical effects of operative treatment for cervical vertebral fracture and dislocation associated with unilateral vertebral artery injury. METHODS: This group consisted of 76 cases of closed cervical spine trauma combined with unilateral vertebral artery injury (23 cases of bilateral facet dislocation, 28 unilateral facet dislocation and 25 fracture). All patients underwent prospective examination of cervical spine MRI and vertebral artery two-dimensional time-of-flight (2D TOF) magnetic resonance angiography (MRA), and anterior cervical decompression. The healthy vertebral artery paths were evaluated before the surgery, and were protected during the surgery according to the anatomical signs. RESULTS: There were no acute or chronic clinical damage symptoms in 76 cases after surgery. No neural damage symptoms were observed in patients with normal neural functions. The neural functions of incomplete paralyzed patients were improved in different grades. CONCLUSIONS: Reliable anterior operation can produce good results for cervical fracture and dislocation with unilateral vertebral artery injury. Detecting the course of uninjured vertebral artery before operation and locating the anatomical site during operation are effective to avoid damaging vertebral artery of uninjured side.

Construction of a NT-3 sustained-release system cross-linked with an acellular spinal cord scaffold and its effects on differentiation of cultured bone marrow mesenchymal stem cells.

OBJECTIVE: This study sought to promote the adhesion, proliferation and differentiation of rat bone marrow mesenchymal stem cells by constructing a neurotrophin-3 (NT-3) sustained-release system cross-linked with an acellular spinal cord scaffold. METHODS: 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) chemistry combined with chemical extraction was used to construct an acellular spinal cord scaffold. The decellularization completion was validated. An EDC cross-linking method was used to construct the NT-3 cross-linked acellular spinal scaffold. ELISA was used to verify sustained release of NT-3; the dorsal root ganglion method was used to verify the biological activity of the sustained-release NT-3. DAPI staining was used to confirm the adhesion of the cultured rat bone marrow mesenchymal stem cells (P3) to the NT-3 scaffold, and cell counting kit-8 (CCK-8) analysis was used to verify the cellular proliferation after 24 h and 48 h of culture. Immunohistochemistry was used to confirm the differentiation of the bone marrow cells into neuron-like cells. RESULTS: An NT-3 sustained-release system cross-linked to an acellular spinal cord scaffold was successfully constructed. Sustained-release NT-3 could persist for 35 days and had biological activity for at least 21 days. It could promote the adhesion, proliferation and differentiation of rat bone marrow mesenchymal stem cells. CONCLUSION: As a composite scaffold, an NT-3 sustained-release system cross-linked with an acellular spinal cord scaffold has potential applications for tissue engineering.

Preparation of an acellular spinal cord scaffold to improve its biological properties.

In recent years, acellular spinal cord scaffolds have been extensively studied in tissue engineering. Notably, acellular spinal cord scaffolds may be used to treat spinal cord injury; however, the method of preparation can result in low efficiency and may affect the biological properties of cells. This study aimed to use EDC crosslinking, combined with chemical extraction for tissue decellularization, in order to improve the efficiency of acellular scaffolds. To make the improved stent available for the clinical treatment of spinal cord injury, it is necessary to study its immunogenicity. Therefore, this study also focused on the adherence of rat bone marrow mesenchymal stem cells to scaffolds, and their differentiation into neuron­like cells in the presence of suitable trophic factors. The results revealed that EDC crosslinking combined with chemical extraction methods may significantly improve the efficiency of acellular scaffolds, and may also confer better biological characteristics, including improved immunogenicity. Notably, it was able to promote adhesion of rat bone marrow mesenchymal stem cells and their differentiation into neuron­like cells. These results suggested that the improved preparation method may be promising for the construction of multifunctional acellular scaffolds for the treatment of spinal cord injury.

Control of demyelination for recovery of spinal cord injury.

Since loss of oligodendrocytes and consequent demyelination of spared axons severely impair the functional recovery of injured spinal cord, it is reasonably expected that the reduction of oligodendroglial death and enhanced remyelination of demyelinated axons will have a therapeutic potential to treat spinal cord injury. Amelioration of axonal myelination in the injured spinal cord is valuable for recovery of the neural function of incompletely injured patients. Here, this article presents an overview about the pathophysiology and mechanism of axonal demyelination in spinal cord injury and discusses its therapeutic significance in the treatment of spinal cord injury. Moreover, it further introduces the recent strategies to improve the axonal myeliantion to facilitate functional recovery of spinal cord injury.

CXCL12 induces migration of oligodendrocyte precursor cells through the CXCR4­activated MEK/ERK and PI3K/AKT pathways.

Demyelination is a nervous system disease in which the myelin sheaths of neurons are damaged due to inflammatory reactions, inherited abnormalities or trauma. This damage impairs the conduction of signals in the affected nerves, which in turn causes deficiencies in sensation, movement and cognition. Oligodendrocyte precursor cells (OPCs) are able to induce remyelination. However, the remyelination is suboptimal due to the limited migration of OPCs. In the present study, neonatal OPCs were isolated from rats for the investigation of the role of C­X­C motif chemokine ligand 12 (CXCL12), an important chemokine, in mediating the migration ability of OPCs. The present results demonstrated that CXCL12 stimulation markedly promoted the migration of OPCs and activated the dual specificity mitogen­activated protein kinase kinase 1 (MEK)/extracellular signal­regulated kinase (ERK) and phosphoinositide 3­kinase (PI3K)/RAC­α serine/threonine­protein kinase (AKT) pathways. Knockdown of C­X­C motif chemokine receptor 4 (CXCR4; a receptor of CXCL12) reversed the CXCL12­induced migration of OPCs and blocked the MEK/ERK and PI3K/AKT pathways. In addition, specific inhibitors of the MEK/ERK and PI3K/AKT pathways significantly reduced the migration of OPCs. Based on these findings, it was concluded that CXCL12 may induce the migration of OPCs through the CXCR4­activated MEK/ERK and PI3K/AKT pathways. The results of the present study support the manipulation of CXCL12­mediated OPC migration to improve remyelination.

A cellular spinal cord scaffold seeded with rat adipose­derived stem cells facilitates functional recovery via enhancing axon regeneration in spinal cord injured rats.

Spinal cord injury (SCI), usually resulting in severe sensory and motor deficits, is a major public health concern. Adipose­derived stem cells (ADSCs), one type of adult stem cell, are free from ethical restriction, easily isolated and enriched. Therefore, ADSCs may provide a feasible cell source for cell­based therapies in treatment of SCI. The present study successfully isolated rat ADSCs (rADSCs) from Sprague­Dawley male rats and co­cultured them with acellular spinal cord scaffolds (ASCs). Then, a rat spinal cord hemisection model was built and rats were randomly divided into 3 groups: SCI only, ASC only, and ASC + ADSCs. Furthermore, behavioral tests were conducted to evaluate functional recovery. Hematoxylin & Eosin staining and immunofluorence were carried out to assess histopathological remodeling. In addition, biotinylated dextran amines anterograde tracing was employed to visualize axon regeneration. The data demonstrated that harvested cells, which were positive for cell surface antigen cluster of differentiation (CD) 29, CD44 and CD90 and negative for CD4, detected by flow cytometry analysis, held the potential to differentiate into osteocytes and adipocytes. Rats that received transplantation of ASCs seeded with rADSCs benefited greatly in functional recovery through facilitation of histopathological rehabilitation, axon regeneration and reduction of reactive gliosis. rADSCs co­cultured with ASCs may survive and integrate into the host spinal cord on day 14 post­SCI.

Clinical study and comparison of magnetic resonance angiography (MRA) and angiography diagnosis of blunt vertebral artery injury.

BACKGROUND: Two-dimensional time-of-flight (2D TOF) magnetic resonance angiography (MRA) is the major method for detecting vertebral artery injury (VAI). But there is still controversy over MRA's accuracy in detecting VAI of varying degrees, a technique for which there are no animal studies found in the literature. The purpose of this study was to evaluate the value of MRA for detecting vertebral artery injury in cervical spinal trauma patients and to conduct a comparative study of MRA and angiography of blunt vertebral artery injury in an animal experiment. METHODS: In clinical study, 319 patients with close cervical spinal trauma underwent 2D TOF MRA prospective examination. The strike-induced flexion injury model of the cervical spine was constructed based on animal experiment with 14 adult dogs. X-ray studies were performed immediately after injury. 2D TOF MRA and angiography were formed within 24 to 36 hours. RESULTS: Vertebral artery injury was detected by 2D TOF MRA in 52 of the 319 patients. Of the 52 patients, there were 51 unilateral vertebral artery injuries, including 22 injuries on the left vertebral artery and 29 on the right vertebral artery. One patient sustained bilateral vertebral artery injury. Seven dogs had unilateral VAI (5 on the left, 2 on the right), and two dogs had narrower-than-normal left vertebral arteries on MRA examination. Angiography showed occlusion exactly in seven dogs with unilateral vertebral artery injury detected by MRA and no abnormal findings were detected in five dogs without vertebral artery injury on MRA. In two dogs with incomplete left vertebral artery flow-related enhancement on MRA, angiography showed occlusion in one dog and no vertebral injury with normal image in the other. CONCLUSIONS: 2D TOF MRA is an effective detection method of blunt vertebral artery injury but it might not be able to differentiate spasm, a small disruption of intima, from others under certain conditions.

Cervical Disk Replacement Combined With Cage Fusion for the Treatment of Multilevel Cervical Disk Herniation.

STUDY DESIGN: This is a prospective study of artificial disk replacement combined with cage fusion for the treatment of multilevel cervical disk herniation. OBJECTIVE: To evaluate the clinical outcome of Bryan cervical disk replacement combined with adjacent segment cage fusion in the treatment of patients with multilevel cervical disk herniation. To observe neurological improvement and interpret the radiographic findings. SUMMARY OF BACKGROUND DATA: It is generally considered that 1-level cervical disk replacement had an excellent intermediate clinical outcome. There was no final conclusion about the disk replacement for the treatment of multilevel cervical disk disease. The negative factors include possible complication, high cost, and contraindication for disk replacement at one of the multisegments. Disk replacement combined with adjacent segment cage fusion may be an option for the treatment of multilevel cervical disk disease for certain patients. METHODS: There were 26 patients with multilevel cervical disk herniation who underwent 1-level disk replacement and adjacent segment cage fusion. Of the patients, there were 17 male and 9 female, aged between 35 and 63 (mean age 47 y). The herniated disk was located at C3-C4, C4-C5 in 1 case, C4-C5, C5-C6 in 11cases, C5-C6, C6-C7 in 7 cases, C4-C5, C6-C7 in 3 cases, and C4-C5, C5-C6, C6-C7 in 4 cases. There were 12 cases with myelopathy and 14 patients with radiculopathy. The stabilization and the range of motion of implanted disk, the fusion of cage, and the displacement of cage were observed on dynamic radiograph postoperatively. The clinical symptoms and the neurological functions were evaluated based on the Japanese Orthopaedic Association Scale score (17 points), neck disability index score, and Odom's Criteria. RESULTS: All patients underwent 1-level Bryan disk replacement and cage fusion on adjacent segment. The replacement segment and fusion segment were located next to each other among 23 patients. They were not next to each other in 3 cases. The follow-up was 24 to 47 months. Definite stabilization was achieved for all Bryan disks. The average range of motion at replaced level was 9.5 degrees postoperatively. Solid fusion was achieved in all cages. There was no subsidence or displacement of cage. The Japanese Orthopaedic Association Scale score (17 points) rose from 9.2 to 13.5 at final follow-up. The neck disability index was reduced from 40.8 to 28.5 at final follow-up. The clinical success (excellent/good/fair) based on Odom's Criteria were 84.6%. CONCLUSIONS: Definite stabilization and satisfactory mobility were achieved after cervical disk replacement and cage fusion. This provides an effective option for the treatment of multilevel cervical disk herniation. The evaluation of high fusion rate of cage may need to accumulate more clinical cases.

Preparation and characterization of genipin-crosslinked rat acellular spinal cord scaffolds.

The feasibility of rat acellular spinal cord scaffolds for tissue engineering applications was investigated. Fresh rat spinal cords were decellularized and crosslinked with genipin (GP) to improve their structural stability and mechanical properties. The GP-crosslinked spinal cord scaffolds possessed a porous structure with an average pore diameter of 31.1 µm and a porosity of 81.5%. The resultant scaffolds exhibited a water uptake ratio of 229%, and moderate in vitro degradation rates of less than 5% in phosphate-buffered saline (PBS) and slightly more than 20% in trypsin-containing buffer, within 14 days. The ultimate tensile strength and elastic modulus of GP-crosslinked spinal cord scaffolds were determined to be 0.193±0.064 MPa and 1.541±0.082 MPa, respectively. Compared with glutaraldehyde (GA)-crosslinked acellular spinal cord scaffolds, GP-crosslinked scaffolds demonstrated similar microstructure and mechanical properties but superior biocompatibility as indicated by cytotoxicity evaluation and rat mesenchymal stem cell (MSC) adhesion behavior. Cells were able to penetrate throughout the crosslinked scaffold due to the presence of an interconnected porous structure. The low cytotoxicity of GP facilitated cell proliferation and extracellular matrix (ECM) secretion in vitro on the crosslinked scaffolds over 7 days. Thus, these GP-crosslinked spinal cord scaffolds show great promise for tissue engineering applications.

Transplantation of oligodendrocyte precursor cells improves myelination and promotes functional recovery after spinal cord injury.

Loss of oligodendrocytes and demyelination further impair neural function after spinal cord injury (SCI). Replacement of lost oligodendrocytes and improvement of myelination have a therapeutic significance in treatment of SCI. Here, we transplanted oligodendrocyte precursor cells (OPCs) to improve myelination in a rat model of contusive SCI. The labelled OPCs were transplanted to injured cord 7 days after injury. As a result, the implanted cells still survived in vivo 8 weeks after transplantation. They proliferated, integrated and differentiated in the injured cord. In the OPCs-treated rats, enhanced myelination in the lesioned area was observed and substantial improvement of motor function and nerve conduction was also recorded. Thus, this study provides strong evidence to support that transplantation of OPCs could improve myelination of injured cord and enhance functional recovery after contusive SCI.

In vitro culture and characterization of oligodendrocyte precursor cells derived from neonatal rats.

OBJECTIVES: The pathologic changes of demyelination after spinal cord injury (SCI) significantly impair functional recovery of lesioned spinal cord. At present, transplantation of myelinating cells is regarded as a promising strategy for treating demyelination following SCI. Hence, the In vitro culture and growth, differentiation and proliferation of oligodendrocyte precursor cells (OPCs) were intensively investigated in this study. METHODS: In vitro cells from cerebral cortices of neonatal rats were primarily cultured and OPCs were then separated by shaking process and differential adhesion. Following cultured in the conditional medium, growth pattern and differentiation of OPCs were continuously studied by both light microscopy and scanning electron microscopy. Furthermore, maturation of OPCs was detected immunochemically and proliferative ability of OPCs In vitro was also evaluated by methyl thiazolyl tetrazolium (MTT) assay. RESULTS: The distinct stratification of glial cells usually developed around 9-10 days in the primary culture. The OPCs were found primarily living on the surface of confluent astrocytes and these cells typically displayed the simple appearance of immature cells. Furthermore, the OPCs progressively developed in the conditional medium, and these differentiated cells underwent dramatic changes of morphology and also expressed different specific markers. Moreover, the OPCs also proved by MTT assay to proliferate significantly while cultured In vitro. DISCUSSION: Demyelination prevents recovery of neural function following SCI. Demyelination has already become a potential therapeutic target for this insidious and challenging problem. The In vitro culture and biological characteristics of OPCs are fundamental and necessary for further investigation of cell transplantation in vivo. Growth pattern, differentiation and proliferation are very vital for therapeutical effects of OPCs following transplantation after SCI.

Acute traumatic cervical cord injury in patients with os odontoideum.

We retrospectively reviewed acute cervical cord injury after minor trauma in 10 patients with os odontoideum. Their clinical history, neurological symptoms, radiological investigations, follow-up period, American Spinal Injury Association impairment classification and motor score were reviewed. Before their traumatic injury, three patients were asymptomatic and seven reported myelopathic symptoms, including four patients with neck pain, two patients with unsteadiness and one patient with dizziness. Falls were the most common cause of injury (n=6), followed by minor motor vehicle accidents (n=3) and assault (n=1). MRI and dynamic cervical lateral radiographs showed that all patients had atlantoaxial instability and cord compression. Most patients had spinal cord thinning and hyperintensity on T2-weighted MRI. Spinal cord compression was posterior (n=5), or both anterior and posterior (n=5). All patients underwent posterior rigid screw fixation and fusion, including atlantoaxial fusion (n=8) and occipitocervical fusion (n=2). We conclude that patients with asymptomatic or myelopathic atlantoaxial instability secondary to os odontoideum are at risk for acute spinal cord injury after minor traumatic injury. Fixation and fusion should be undertaken as prophylactic treatment for patients at risk of developing myelopathy and to avoid the neurological deterioration associated with acute traumatic cervical cord injury.

Promoting axonal myelination for improving neurological recovery in spinal cord injury.

Spinal cord injury (SCI) remains a major challenge to neurological research. Progress in both basic and clinical research has shown that neurons and oligodendrocytes are equally susceptible to such injury. In injuries secondary to direct injury to the spinal cord, oligodendrocytes appear to be highly vulnerable to various harmful factors and eventually undergo apoptosis. Due to the loss of myelinating cells, axonal demyelination is likely to affect the neural function of surviving axons. Recently, improved understanding of the pathological changes ongoing in oligodendrocytes following injury has shown that the death of these cells plays a vital role in the demyelination of axons. Because the demise of oligodendrocytes and subsequent axonal demyelination impair the conductive capacity of surviving axons, it seems reasonable to expect that reducing oligodendrocyte death and improving axonal myelination holds potential for the treatment of SCI. In the clinical setting, such therapy may help these patients, including those with complete functional injury and those with white matter preservation. Accordingly, it appears reasonable that improving axonal myelination and the conductive capacity of surviving axons will be of great benefit in patients with mild to moderate injury of the spinal cord. We here present a review of the pathophysiology and mechanisms of oligodendrocyte death and axonal demyelination that follow injury to the spinal cord, and discuss the potential for treating them. Because cell transplantation has recently become a promising strategy for replacing lost oligodendrocytes and improving axonal myelination in SCI, we also discuss the significance of cell transplantation as a novel approach to treating SCI.

[Identification of glial cell line-derived neurotrophic factor recombinant retroviral vector and establishment of its packaging cell line PA317].

OBJECTIVE: To identify glial cell line-derived neurotrophic factor (GDNF) recombinant retroviral vector and to establish its packaging cell line PA317. METHODS: PA317 cells were transfected with recombinant retroviral vector pLXSN-GDNF using liposomes. The recombinant retroviral particles were then harvested from culture media of G418 resistant transfected cells and analyzed using RT-PCR. Virus titers in supernatants were investigated. RESULTS: Sequencing date indicated that GDNF gene was exactly identical to the sequence in the GeneBank. PA317 cells were transfected with recombinant retroviral vector pLXSN-GDNF using liposomes, and virus titers in supernatants harvested from culture media of (G418 resistant transfected cells were 10(4)10(5) CFU/ml. CONCLUSION: Packaging cell line PA317/pLXSN-GDNF was established.

[Total hip arthroplasty for treatment of developmental dysplasia of the hip].

OBJECTIVE: To summarize the techniques of the total hip arthroplasty in the treatment of osteoarthritis secondary to developmental dysplasia of the hip joint (DDH). METHODS: Between February 1986 and November 2004, a total of 32 hips in 24 patients with advanced osteoarthritis secondary to DDH underwent the total hip arthroplasty. Among the patients, 4 were male and 20 were female, with their ages ranging from 33 to 59 years and an average age of 47 years. The bilateral arthroplasty was performed in 8 patients and the unilateral arthroplasty in 16 patients. The patients mainly suffered from pain and claudication. According to the Hartofilakidis classification, semidislocation occurred in 2 hips, low-dislocation in 21 hips, and high-dislocation in 9 hips; and the Harris scores before operation were 56.70 +/- 2.75, 36.09 +/- 4.16, and 29.45 +/- 2.16, respectively. RESULTS: All the patients were followed up for 6 months to 8 years (averaged 3 years and 4 months). The Harris scores after operation were 93.10 +/- 2.10, 92.7 +/- 3.20, and 88.09+/- 3.67, respectively. The differences between preoperation and postoperation were significant (P < 0.01). All the patients were pain-free and there was no sign of aseptic loosening and subsidence. CONCLUSION: The total hip arthroplasty is an effective method for the treatment of osteoarthritis secondary to DDH. The key techniques for the total hip arthroplasty are as follows: deepening the medial wall of the acetabulum, improving the techniques of the bone graft, and firmly placing the acetabular component in the true acetabulum.