RÉSUMÉ
BACKGROUND:Endothelin has been found to be involved in the breakdown of the blood-spinal cord barrier after spinal cord injury,and stem cell-derived exosomes can reduce the permeability of the blood-spinal cord barrier and repair spinal cord injury. OBJECTIVE:To investigate whether exosomes produced by human umbilical cord mesenchymal stem cells can reduce the permeability of the blood-spinal cord barrier by inhibiting endothelin-1 expression,thus repairing spinal cord injury. METHODS:Exosomes were extracted from the cultured supernatant by the hyperspeed centrifugation method.The morphology of exosomes was observed by transmission electron microscope.The expression levels of tsg101 and CD63 were detected by western blot assay.Eighty SD rats were randomly divided into sham operation group,model group,exosome group,and endothelin-1 group(n=20).The modified Allen's method was used to create the rat model of spinal cord injury.In the endothelin-1 group,10 μL(1 μg/mL)endothelin-1 was injected directly into the injured area with a microsyringe.Immediately,1 day,2 days after operation,sham operation group and model group were injected with 200 μL PBS solution through the tail vein;the exosome group and endothelin-1 group were injected with 200 μL exosome(200 μg/mL)solution through the tail vein,respectively.Hind limb motor function scores were performed on days 1,3,7,14 and 21 after spinal cord injury.The blood-spinal cord barrier permeability was observed by Evans blue staining on day 7 after injury.The expression levels of tight junction proteins β-Catenin,ZO-1,Occludin and endothelin-1 in the spinal cord were detected by western blot assay. RESULTS AND CONCLUSION:(1)Basso-Beattie-Bresnahan score in the exosome group was significantly higher than that in the model group at 3-21 days after injury(P<0.05).Hematoxylin-eosin staining showed that spinal cord injury was greatly reduced in the exosome group compared with the model group.Basso-Beattie-Bresnahan score in the endothelin-1 group was significantly decreased compared with the exosome group(P<0.05).Spinal cord injury was more severe in the endothelin-1 group than that in the exosome group.(2)The expression of endothelin-1 in the model group was significantly increased compared with the sham operation group(P<0.05),and the expression of endothelin-1 in the exosome group was significantly decreased compared with the model group(P<0.05).(3)The blood-spinal cord barrier Evans blue exudate in the exosome group was significantly decreased compared with the model group(P<0.05).The expression levels of the tight junction proteins β-Catenin,Occludin and ZO-1 in the exosome group were increased(P<0.05);the Evans blue exudate in the endothelin-1 group was significantly increased compared with the exosome group(P<0.05).The expression level of tight junction protein was significantly decreased compared with the exosome group(P<0.05).(4)The results show that human umbilical cord mesenchymal cell-derived exosomes protect the permeability of the blood-spinal cord barrier by down-regulating the expression of endothelin-1 and play a role in the repair of spinal cord injury.
RÉSUMÉ
Objective To investigate the selection of surgery and clinical outcomes of upper cervical injuries.Methods 25 upper cervical injury patients were involved in this retrospective study from November 2011 to June 2014.Including 20 males and 5 females with mean age of 37.1 years old (range,14-55 years old).Individual operation methods were based on the comprehensive evaluation of specific situations including the clinical manifestation,the type of the injuries and the imaging data.HaloVest distraction was applicated before operation.The surgery by anterior approach were performed for 7 patients and posterior approach were performed for 18 patients.Preoperative and postoperative American Spinal Injury Association (ASIA) grade and Functional Independence Measurement (FIM) score were studied to evaluate the nerve functional restoration.Imaging data before and after the operation were contrasted to evaluate the reduction of the fracture,the bone union,the fusion of the bone graft and the condition of the internal fixation.Wilcoxon Singed Rank Test was applied to compare the FIM score between pre-operation and last follow-up.Results 15 patients presented neurological function deficit because of cervical spinal cord compromise.All cases were followed up for 6-35 months (mean 18.2 months),showing good clinical and radiological effects.Solid fusion was obtained in all patients among 3-12 months.The ASIA grade improved by an average of 1.1 (6 months after operation) and 1.2 (12 months after operation).There was significant difference in FIM score between pre-operation and last follow-up.One patient got cerebrospinal fluid leakage.Conservative treatment was implemented with the Trendelenburg position,rehydration fluids and so on.Removal of drainage tube 8 days later when the drainage was less than 30 ml/24 h.No incision infection,cerebrospinal fluid leakage,migration or breakage of internal fixation was observed at the last follow-up.Conclusion The type of upper cervical injuries are complicated,the characteristics of fracture,dislocation and nerve injury in different patients are different.The specific situation should be evaluated comprehensively to make individual operation methods.The success of the operation requires the proficiency of the anatomic basis,the biomechanical characteristics,precise entrance point and direction in operation,appropriate diameter of the screw and suitable depth of the screw road.
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BACKGROUND:A large number of studies have shown that adult stem cels derived from multiple tissues are available to differentiate towards nucleus pulposus-like celsin vitro. It is unclear whether mesenchymal stem cels derived from nucleus pulposus tissues have the ability to differentiate towards nucleus pulposus-like phenotypes induced by transforming growth factor-beta 1. Up to now, there are few reports on the difference between the differentiation ability of mesenchymal stem cels derived from nucleus pulposus tissues and adipose-derived mesenchymal stem cels. OBJECTIVE:To compare the ability of mesenchymal stem cels derived from nucleus pulposus tissues and adipose-derived mesenchymal stem cels differentiating into nucleus pulposus-like cels under induction of transforming growth factor-beta 1. METHODS:The groin fat tissue and the coccygeal spine of rats were taken respectively to isolate and culture mesenchymal stem cels derived from nucleus pulposus tissues and adipose-derived mesenchymal stem cels by mechanical enzyme digestion method. Flow cytometry was employed to detect the expression of CD105, CD90, CD29, CD45, CD44, CD34, and CD24 of both two kinds of stem cels. Mesenchymal stem cels derived from nucleus pulposus tissues and adipose-derived mesenchymal stem cels were divided into complete induction group (complete induction medium with transforming growth factor-beta 1), incomplete induction group (complete induction medium without transforming growth factor-beta 1) and control group(DMEM/F12 containing 10% fetal bovine serum and 100 mg/L penicilin/streptomycin), respectively. After 14 days of culture, real-time PCR was used to detect the expression of colagen type II, Aggrecan and SOX-9 in each group. RESULTS AND CONCLUSION:CD105, CD90, CD29 expressed positively and CD45, CD44, CD34, CD24 negatively in both two kinds of stem cels. After 14 days of induced differentiation, the expressions of colagen type II, Aggrecan and SOX-9 in the two kinds of cels were significantly higher in the complete induction groups than in the control groups (P < 0.05). Under the induction of transforming growth factor-beta 1, the expression of colagen type II, Aggrecan and SOX-9 in mesenchymal stem cels derived from nucleus pulposus tissues was significantly higher than that in adipose-derived mesenchymal stem cels (P < 0.05). These findings suggest that both two kinds of mesenchymal stem cels have the ability to differentiate towards nucleus pulposus-like cels induced by transforming growth factor-beta, and mesenchymal stem cels derived from nucleus pulposus tissues may be more suitable as seed cels for nucleus pulposus tissue engineering research.