RÉSUMÉ
BACKGROUND:Mechanical stimulation has been confirmed to promote osteogenic differentiation of bone marrow stromal stem cells,but the mechanism is unknown.Primary cilia are important mechanoreceptors and regulate various signaling pathways such as TGF-β1/BMP-2/SMAD.They are likely to be important targets for mechanical regulation of bone marrow stromal stem cells. OBJECTIVE:To investigate the effect and mechanism of fluid shear stress on osteogenic differentiation of bone marrow stromal stem cells. METHODS:Rat bone marrow stromal stem cells were divided into control group,mechanical stimulation group(fluid shear mechanics intervention by shaking table),mechanical stimulation + IFT88 silencing group(mechanical stimulation + silencing IFT88 expression with siRNA).After 24 hours of intervention,qRT-PCR was utilized to determine the expression of transforming growth factor β1 and bone morphogenetic protein 2.Western blot assay was used to detect the expression of phosphorylated SMAD2/3 protein.Immunofluorescent staining of primary cilia was conducted and morphology was analyzed. RESULTS AND CONCLUSION:Shear stress stimulation could promote the transcriptional activity of transforming growth factor β1 and bone morphogenetic protein 2 genes,and increase the expression of phosphorylated SMAD2/3 protein.After siRNA interfered with primary cilia,this mechanical response effect was significantly reduced.There was a Spearman correlation between the change ratio of the primary cilium area of bone marrow stromal stem cells and the increased ratio of transforming growth factor β1 and bone morphogenetic protein 2 gene transcription.These findings indicate that primary cilia/intraflagellar transport mediates the activation of fluid shear stress-responsive transforming growth factor β1/bone morphogenetic protein 2/SMAD signaling pathway and promotes osteogenic differentiation of bone marrow stromal stem cells.
RÉSUMÉ
BACKGROUND:Cervical neutral position magnetic resonance imaging is widely used for the diagnosis and treatment of cervical spondylotic myelopathy.However,it is not possible for patients to maintain the exact same position of the head and neck during repeated cervical magnetic resonance imaging examinations.The cervical spine undergoes minor flexion and extension movements in the sagittal plane,and the head may have a certain degree of variation in flexion and extension.Whether these changes in the neutral position of the cervical spine affect the volume of cervical discs herniation and cervical curvature is unclear. OBJECTIVE:Using artificial intelligence-assisted measurement,this study aimed to analyze the accuracy and reliability of magnetic resonance imaging examinations for measuring the volume of cervical discs herniation and cervical curvature in patients with cervical spondylotic myelopathy undergoing two consecutive cervical neutral positions in the short term. METHODS:A retrospective study was conducted on patients with cervical spondylotic myelopathy who underwent conservative treatment and underwent two consecutive cervical magnetic resonance imaging examinations within three months between June 2012 and June 2023.We proposed the use of occipital-thoracic distance and occipital-thoracic angle to evaluate the variation in flexion and extension of the head in the neutral position of the cervical spine.Based on the changes in occipital-thoracic angle,patients were divided into occipital-thoracic angle increase group and occipital-thoracic angle decrease group.Cervical discs herniation volume,C2-6 Cobb angle,and cervical(C3-C7)curvature were measured using artificial intelligence-assisted measurement software.Normal distribution data were represented by mean±SD,while non-normal distribution data were represented by the median(interquartile range).Spearman's rank correlation coefficient was used to analyze the correlation between changes in Cobb angle,cervical(C3-C7)curvature,and cervical discs herniation volume. RESULTS AND CONCLUSION:(1)A total of 104 patients and 326 cervical discs herniation were included in the study.There were 47 patients in the occipital-thoracic angle increase group and 57 patients in the occipital-thoracic angle decrease group.(2)Extension and flexion index of the head:There were no significant differences in occipital-thoracic distance and occipital-thoracic angle during the initial diagnosis and follow-up examination.The variation of occipital-thoracic distance was 0.035(3.23)mm,and the variation of occipital-thoracic angle was-0.31(3.28)°.The deviation range of occipital-thoracic distance and occipital-thoracic angle was small,and there was no significant correlation.(3)Cervical curvature index:There were no significant differences in C2-6 Cobb angle and C3-C7 curvature during the initial diagnosis and follow-up examination.There were no significant differences in C2-6 Cobb angle and C3-C7 curvature between the occipital-thoracic angle increase group and occipital-thoracic angle decrease group.(4)There was no significant difference in volume of cervical discs herniation during the initial diagnosis and follow-up examination.There was no significant difference in volume of cervical discs herniation between the occipital-thoracic angle increase group and occipital-thoracic angle decrease group.There was no significant correlation between the change of cervical discs herniation volume and the change of C2-6 Cobb angle and the cervical(C3-C7)curvature.(5)These results indicate that in the neutral position of the cervical spine,there were negligible minor flexion and extension movements in the sagittal plane,and the head was limited to a specific position.Although the head has a certain range of flexion and extension variation,it does not affect the accuracy and reliability of parameters including cervical discs herniation volume,C2-6 Cobb angle,and cervical(C3-C7)curvature.