BACKGROUND Intervertebral disc(IVD) degeneration is a condition characterized by a reduction in the water and extracellular matrix content of the nucleus pulposus(NP) and is considered as one of the dominating contrib...BACKGROUND Intervertebral disc(IVD) degeneration is a condition characterized by a reduction in the water and extracellular matrix content of the nucleus pulposus(NP) and is considered as one of the dominating contributing factors to low back pain. Recent evidence suggests that stromal cell-derived factor 1α(SDF-1α) and its receptor CX-C chemokine receptor type 4(CXCR4) direct the migration of stem cells associated with injury repair in different musculoskeletal tissues.AIM To investigate the effects of SDF-1α on recruitment and chondrogenic differentiation of nucleus pulposus-derived stem cells(NPSCs).METHODS We performed real-time RT-PCR and enzyme-linked immunosorbent assay to examine the expression of SDF-1α in nucleus pulposus cells after treatment with pro-inflammatory cytokines in vitro. An animal model of IVD degeneration was established using annular fibrosus puncture in rat coccygeal discs. Tissue samples were collected from normal control and degeneration groups.Differences in the expression of SDF-1α between the normal and degenerative IVDs were analyzed by immunohistochemistry. The migration capacity of NPSCs induced by SDF-1α was evaluated using wound healing and transwell migration assays. To determine the effect of SDF-1α on chondrogenic differentiation of NPSCs, we conducted cell micromass culture and examined the expression levels of Sox-9, aggrecan, and collagen II. Moreover, the roles of SDF-1/CXCR4 axis in the migration and chondrogenesis differentiation of NPSCs were analyzed by immunofluorescence, immunoblotting, and real-time RT-PCR.RESULTS SDF-1α was significantly upregulated in the native IVD cells cultured in vitro with pro-inflammatory cytokines, such as interleukin-1β and tumor necrosis factor-α, mimicking the degenerative settings. Immunohistochemical staining showed that the level of SDF-1α was also significantly higher in the degenerative group than in the normal group. SDF-1α enhanced the migration capacity of NPSCs in a dose-dependent manner. In addition, SDF-1α induced chondrogenic differentiation of NPSCs, as evidenced by the increased expression of chondrogenic markers using histological and immunoblotting analyses. Realtime RT-PCR, immunoblotting, and immunofluorescence showed that SDF-1αnot only increased CXCR4 expression but also stimulated translocation of CXCR4 from the cytoplasm to membrane, accompanied by cytoskeletal rearrangement.Furthermore, blocking CXCR4 with AMD3100 effectively suppressed the SDF-1α-induced migration and differentiation capacities of NPSCs.CONCLUSION These findings demonstrate that SDF-1α has the potential to enhance recruitment and chondrogenic differentiation of NPSCs via SDF-1/CXCR4 chemotaxis signals that contribute to IVD regeneration.展开更多
Objective:Fragment injury is a type of blast injury that is becoming more and more common in military campaigns and terrorist attacks.Numerical simulation methods investigating the formation of natural fragments and i...Objective:Fragment injury is a type of blast injury that is becoming more and more common in military campaigns and terrorist attacks.Numerical simulation methods investigating the formation of natural fragments and injuries to biological targets are expected to be developed.Methods:A cylindrical warhead model was established and the formation process of natural fragments was simulated using the approach of tied nodes with failure through the explicit finite element(FE)software of LS-DYNA.The interaction between the detonation product and the warhead shell was simulated using the fluidestructure interaction algorithm.A method to simulate the injury of natural fragments to a biological target was presented by transforming Lagrange elements into smooth particle hydrodynamics(SPH)particles after the natural fragments were successfully formed.A computational model of the human thorax was established to simulate the injury induced by natural fragments by the node-to-surface contact algorithm with erosion.Results:The discontinuous velocities of the warhead shell at different locations resulted in the formation of natural fragments with different sizes.The velocities of natural fragments increased rapidly at the initial stage and slowly after the warhead shell fractured.The initial velocities of natural fragments at the central part of the warhead shell were the largest,whereas those at both ends of the warhead shell were the smallest.The natural fragments resulted in bullet holes that were of the same shape as that of the fragments but slightly larger in size than the fragments in the human thorax after they penetrated through.Stress waves propagated in the ribs and enhanced the injury to soft tissues;additionally,ballistic pressure waves ahead of the natural fragments were also an injury factor to the soft tissues.Conclusion:The proposed method is effective in simulating the formation of natural fragments and their injury to biological targets.Moreover,this method will be beneficial for simulating the combined injuries of natural fragments and shock waves to biological targets.展开更多
基金the National Natural Science Foundation of China,No.81772399
文摘BACKGROUND Intervertebral disc(IVD) degeneration is a condition characterized by a reduction in the water and extracellular matrix content of the nucleus pulposus(NP) and is considered as one of the dominating contributing factors to low back pain. Recent evidence suggests that stromal cell-derived factor 1α(SDF-1α) and its receptor CX-C chemokine receptor type 4(CXCR4) direct the migration of stem cells associated with injury repair in different musculoskeletal tissues.AIM To investigate the effects of SDF-1α on recruitment and chondrogenic differentiation of nucleus pulposus-derived stem cells(NPSCs).METHODS We performed real-time RT-PCR and enzyme-linked immunosorbent assay to examine the expression of SDF-1α in nucleus pulposus cells after treatment with pro-inflammatory cytokines in vitro. An animal model of IVD degeneration was established using annular fibrosus puncture in rat coccygeal discs. Tissue samples were collected from normal control and degeneration groups.Differences in the expression of SDF-1α between the normal and degenerative IVDs were analyzed by immunohistochemistry. The migration capacity of NPSCs induced by SDF-1α was evaluated using wound healing and transwell migration assays. To determine the effect of SDF-1α on chondrogenic differentiation of NPSCs, we conducted cell micromass culture and examined the expression levels of Sox-9, aggrecan, and collagen II. Moreover, the roles of SDF-1/CXCR4 axis in the migration and chondrogenesis differentiation of NPSCs were analyzed by immunofluorescence, immunoblotting, and real-time RT-PCR.RESULTS SDF-1α was significantly upregulated in the native IVD cells cultured in vitro with pro-inflammatory cytokines, such as interleukin-1β and tumor necrosis factor-α, mimicking the degenerative settings. Immunohistochemical staining showed that the level of SDF-1α was also significantly higher in the degenerative group than in the normal group. SDF-1α enhanced the migration capacity of NPSCs in a dose-dependent manner. In addition, SDF-1α induced chondrogenic differentiation of NPSCs, as evidenced by the increased expression of chondrogenic markers using histological and immunoblotting analyses. Realtime RT-PCR, immunoblotting, and immunofluorescence showed that SDF-1αnot only increased CXCR4 expression but also stimulated translocation of CXCR4 from the cytoplasm to membrane, accompanied by cytoskeletal rearrangement.Furthermore, blocking CXCR4 with AMD3100 effectively suppressed the SDF-1α-induced migration and differentiation capacities of NPSCs.CONCLUSION These findings demonstrate that SDF-1α has the potential to enhance recruitment and chondrogenic differentiation of NPSCs via SDF-1/CXCR4 chemotaxis signals that contribute to IVD regeneration.
基金The work was funded by the National Science Foundation for Young Scientists of China(11902356)China Postdoctoral Science Foundation(2018M633715)+1 种基金Innovation and Cultivation Fund of the Sixth Medical Center of PLA General Hospital(No.CXPY201825)the Army Scientific Research(LB20182D040012).
文摘Objective:Fragment injury is a type of blast injury that is becoming more and more common in military campaigns and terrorist attacks.Numerical simulation methods investigating the formation of natural fragments and injuries to biological targets are expected to be developed.Methods:A cylindrical warhead model was established and the formation process of natural fragments was simulated using the approach of tied nodes with failure through the explicit finite element(FE)software of LS-DYNA.The interaction between the detonation product and the warhead shell was simulated using the fluidestructure interaction algorithm.A method to simulate the injury of natural fragments to a biological target was presented by transforming Lagrange elements into smooth particle hydrodynamics(SPH)particles after the natural fragments were successfully formed.A computational model of the human thorax was established to simulate the injury induced by natural fragments by the node-to-surface contact algorithm with erosion.Results:The discontinuous velocities of the warhead shell at different locations resulted in the formation of natural fragments with different sizes.The velocities of natural fragments increased rapidly at the initial stage and slowly after the warhead shell fractured.The initial velocities of natural fragments at the central part of the warhead shell were the largest,whereas those at both ends of the warhead shell were the smallest.The natural fragments resulted in bullet holes that were of the same shape as that of the fragments but slightly larger in size than the fragments in the human thorax after they penetrated through.Stress waves propagated in the ribs and enhanced the injury to soft tissues;additionally,ballistic pressure waves ahead of the natural fragments were also an injury factor to the soft tissues.Conclusion:The proposed method is effective in simulating the formation of natural fragments and their injury to biological targets.Moreover,this method will be beneficial for simulating the combined injuries of natural fragments and shock waves to biological targets.
