[Retros Flt-1 decelerates the growth of a murine experimental osteosarcoma].

OBJECTIVE: To examine the influence of vascular endothelial growth factors (VEGF) in controlling the growth of an experimental osteosarcoma in mice by performing retrovirus-mediated sFlt-1 gene modification. METHODS: From March to October 2010 human osteosarcoma G-292 cells were in vitro infected with retroviral vectors encoding soluble Flt-1 or LacZ gene before transplanted into proximal tibiae of immune deficient SCID mice to establish experimental orthotopic osteosarcoma. Daily observation and biweekly microCT were performed to monitor tumor development and progression till sacrifice at 8 weeks after tumor cell inoculation for histological and molecular analyses. RESULTS: Successful transgene expression was confirmed in the culture media of sFlt-1 transduced G-292 cells using ELISA, and with positive X-gal staining of the LacZ transduced cells. Noteworthy tumors were grown in all mice on the tibiae receiving G-292 cell inoculation, with clear detection on microCT images starting 2 weeks after inoculation. Over the time period, tumors derived from sFlt-1 transduced G-292 cells were distinctively smaller in size compared to the ones from wide-type G-292 and G-292-LacZ cells. Histology showed typical osteosarcoma characteristics including severe cellular pleomorphism, bone erosions, and neo-vascularization. Real-time polymerase chain reaction indicated significantly higher sFlt-1 expression in sFlt-1 transduced groups than the wild-type G-292 or LacZ treated groups. Strong expression of oncogenes c-myc and c-fos were also obvious, along with the expression of VEGF in the primary tumor tissue. CONCLUSION: Retrovirus-mediated sFLT-1 gene modification decelerates the osteosarcoma tumor growth in this murine model.

Biomechanical stability of lower cervical spine immediately after discectomy with grafting.

OBJECTIVE: Anterior cervical discectomy is commonly used to treat radiculopathy and myelopathy. Although the size of the implanted graft may influence the clinical outcome of anterior reconstruction of the cervical spine, the ideal graft height remains arguable. The objective of the current study was to study the interrelations of graft height and immediate biomechanical stability in an anterior cervical discectomy model. METHODS: Six fresh-frozen human cadaver cervical spines (C1-T1) were tested in five sequential states. The first state tested was the "normal" state (specimens with intact discs). The other four states were tested after C5-C6 discectomy by the Smith-Robinson graft technique, using graft thicknesses of 100%, 120%, 140%, and 160% of the baseline height. The baseline height was defined as the intervertebral disc height of C5-C6 at the intact stage. Intervertebral segment flexion, extension, bending and rotation of C5-C6 were recorded using a 3D laser scanner and analyzed using Geomagic Studio 5.0 software. RESULTS: Bone grafting at 100% baseline height after discectomy provided the least stability and the greatest movement range. With increasing height of grafts, the movement range of the cervical spine declined. Immediate stability of the operated segments was significantly increased by grafting with 140% and 160% baseline heights compared to the baseline height condition. CONCLUSIONS: Strut-graft with appropriate distraction after Smith-Robinson anterior cervical discectomy plays an important role in the whole immediate biomechanical stability of the lower cervical spine. A graft height of 40% greater than baseline may be ideal after single discectomy in clinical practice.

Destructive pathological changes in the rat spinal cord due to chronic mechanical compression. Laboratory investigation.

OBJECT: Chronic mechanical compression of the spinal cord, which is commonly caused by degeneration of the spine, impairs motor and sensory functions insidiously and progressively. Yet the exact mechanisms of chronic spinal cord compression (SCC) remain to be elucidated. To study the pathophysiology of this condition, the authors developed a simple animal experimental model that reproduced the clinical course of mechanical compression of the spinal cord. METHODS: A custom-designed compression device was implanted on the exposed spinal cord of female Wistar rats between the T-7 and T-9 vertebrae. A root canal screw attached to a plastic plate was tightened 1 complete turn (1 pitch) every 7 days for 6 weeks. The placement of the compression device and the degree of compression were validated every week using radiography. Furthermore, a motor sensory deficit index was also calculated every week. After 3, 6, 9, or 12 weeks, the compressed T7-9 spinal cords were harvested and examined histologically. RESULTS: Lateral projection of the thoracic spine showed a progressively increasing rate of mean spinal cord narrowing in the compression group. Motor and sensory deficiencies were observed from Week 3 onward; paralysis was observed in 2 rats at Week 12. Motor deficiency appeared earlier than sensory deficiency. Obvious pathological changes were observed starting at Week 6. The number of neurons in the gray matter of rats with chronic compression of the spinal cord decreased progressively in the 6- and 9-week compression groups. In the white matter, myelin destruction and loss of axons and glia were noted. The number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive neurons increased in the ventral-to-dorsal direction. The number of TUNEL-positive cells increased from Week 6 onward and peaked at Week 9. CONCLUSIONS: This practical model accurately reproduces characteristic features of clinical chronic SCC, including progressive motor and sensory disturbances after a latency and insidious neuronal loss.

Influence of cryopreserved olfactory ensheathing cells transplantation on axonal regeneration in spinal cord of adult rats.

OBJECTIVE: To observe the effects of cryopreserved olfactory ensheathing cells (OECs) transplantation on axonal regeneration and functional recovery following spinal cord injury in adult rats. METHODS: Twenty-four rats were divided into experimental and control groups, each group having 12 rats. The spinal cord injury was established by transecting the spinal cord at T10 level with microsurgery scissors. OECs were purified from SD rat olfactory bulb and cultured in DMEM (Dulbecco's minimum essential medium) and cryopreserved (-120 degree) for two weeks. OECs suspension [(1-1.4)x10(5)/ul] was transplanted into transected spinal cord, while the DMEM solution was injected instead in the control group. At 6 and 12 weeks after transplantation, the rats were evaluated with climbing test and MEP (moter evoked potentials) monitoring. The samples of spinal cord were procured and studied with histological and immunohistochemical stainings. RESULTS: At 6 weeks after transplantation, all of the rats in both transplanted and control groups were paraplegic, and MEPs could not be recorded. Morphology of transplanted OECs was normal, and OECs were interfused with host well. Axons could regrow into gap tissue between the spinal cords. Both OECs and regrown axons were immunoreactive for MBP. No regrown axons were found in the control group. At 12 weeks after transplantation, 2 rats (2/7) had lower extremities muscle contraction, 2 rats (2/7) had hip and/or knee active movement, and MEP of 5 rats (5/7) could be recorded in the calf in the transplantation group. None of the rats (7/7) in the control group had functional improvement, and none had MEPs recorded. In the transplanted group, histological and immunohistochemical methods showed the number of transplanted OECs reduced and some regrown axons had reached the end of transected spinal cord. However, no regrown axons could be seen except scar formation in the control group. CONCLUSIONS: Cryopreserved OECs could integrated with the host and promote regrowing axons across the transected spinal cord ends.

[Treatment of fracture involved articular surface with absorbable screws and rods].

OBJECTIVE: To investigate the treatment results of fracture involved articular surface with absorbable screws and rods. METHODS: From October 1995 to May 2002, 32 patients with fracture involved articular surface were treated with absorbable screws and rods with the materials of SR-PGA and SR-PLLA. Bone traction or plaster external fixation were carried out postoperatively. RESULTS: The followed-up period varied from 3 months to 78 months, with an average of 18.5 months. According to the articular function evaluation criteria, the results were excellent in 24 patients, good in 6 patients and fair in 2 patients. The excellent and good rate was 93.7%. The fractures healed, without dislocation, infection and local effusion. CONCLUSION: Internal fixation of absorbable screws and rods is a perfect procedure for treating fracture involved articular surface, which avoided the pain of taking out internal fixation materials of the second operation.