周期性机械应力对髓核细胞增殖和细胞外基质表达的影响

目的：探讨周期性机械应力对髓核细胞增殖和细胞外基质表达的影响。方法：对兔髓核细胞进行体外细胞培养,对细胞施加周期性机械应力（0.25Mpa,0.1Hz）。实验分为2组,不加压组和加压组,不加压组置于单纯旋转式生物反应器内,加压组每天置于周期性机械应力场内2小时。分别于3天,7天检测细胞数目以及聚集蛋白聚糖（aggrecan）和Ⅱ型胶原的基因表达。结果：髓核细胞的增殖和聚集蛋白聚糖、Ⅱ型胶原基因的表达水平与周期性压力密切相关,在周期性机械应力刺激下髓核细胞增殖明显,细胞外基质的分泌增加,组织工程髓核细胞的活性显著提高。结论：周期性机械应力能够显著促进髓核细胞增殖,同时上调聚集蛋白聚糖、Ⅱ型胶原的基因的表达。     

大鼠髓核细胞原代培养及表型鉴定

目的:探讨Ⅱ型胶原酶联合透明质酸酶消化分离培养髓核细胞及免疫细胞化学表型鉴定的可行性。方法:无菌条件下分离SD大鼠凝胶状髓核,采用Ⅱ型胶原酶联合透明质酸酶消化分离髓核细胞并连续培养,倒置相差显微镜下观察,随后进行免疫细胞化学染色检测不同代次髓核细胞HIF-1、Ⅰ、Ⅱ型胶原、MMP2及蛋白聚糖的表达情况,并给予MTT法测定髓核细胞生长曲线。结果:Ⅱ型胶原酶联合透明质酸酶分离培养原代髓核细胞需要12 d左右贴壁,达95%融合需要34 d,而传代髓核细胞贴壁速率明显增快至10 h,且其倍增时间约为2.5 d;免疫细胞化学显示髓核细胞均表达HIF-1、Ⅰ、Ⅱ型胶原、MMP2和蛋白聚糖,且随着髓核细胞传代其HIF-1α、HIF-1β、Ⅰ型胶原及MMP2表达均增加,但Ⅱ型胶原表达降低,而蛋白聚糖表达无明显差异;MTT法显示随着髓核细胞传代其增殖有所减缓。结论:Ⅱ型胶原酶联合透明质酸酶可成功分离髓核细胞,提高培养效率,且HIF-1α、HIF-1β、Ⅰ、Ⅱ型胶原及MMP2可作为髓核细胞表型分子用于髓核细胞的鉴定。     

hBMP-7基因转染对原代培养兔髓核细胞生物学活性的影响*

摘要目的：探讨原代培养的兔髓核细胞转染腺病毒载体介导的人骨形态发生蛋白-7(hBMP-7)基因后对其生物学活性的影响。方 法：根据兔髓核细胞转染方式的不同,分为hBMP7 组、LacZ组、未转染组三组,hBMP7 组采用腺病毒载体介导的hBMP7 进行转 染,LacZ组转染LacZ基因,未转染组不转染任何基因。比较三组细胞增殖、硫酸糖胺多糖（GAG）产量、Ⅱ型胶原产量有无差异。 结果：处理方式和转染后时间对细胞增殖、GAG产量、Ⅱ型胶原产量有交互作用（P＜0.05）,hBMP7 组细胞增殖、GAG 产量、Ⅱ型 胶原产量高于LacZ 组、未转染组,差异有统计学意义（P＜0.05）,LacZ组和未转染组细胞增殖、GAG 产量、Ⅱ型胶原产量差异无 统计学意义（P＞0.05）。结论：hBMP-7 基因转染可提高髓核细胞增殖能力,促进其产生细胞外基质。     

hBMP-7基因转染对原代培养兔髓核细胞生物学活性的影响

目的：探讨原代培养的兔髓核细胞转染腺病毒载体介导的人骨形态发生蛋白-7（hBMP-7）基因后对其生物学活性的影响。方法：根据兔髓核细胞转染方式的不同,分为hBMP7组、Lacz组、未转染组三组,hBMP7组采用腺病毒载体介导的hBMP7进行转染,LacZ组转染LacZ基因,未转染组不转染任何基因。比较三组细胞增殖、硫酸糖胺多糖（GAG）产量、Ⅱ型胶原产量有无差异。结果：处理方式和转染后时间对细胞增殖、GAG产量、Ⅱ型胶原产量有交互作用（P〈0．05）,hBMP7组细胞增殖、GAG产量、Ⅱ型胶原产量高于LacZ组、未转染组,差异有统计学意义（P〈0．05）,LacZ组和未转染组细胞增殖、GAG产量、Ⅱ型胶原产量差异无统计学意义（P〉0．05）。结论：hBMP．7基因转染可提高髓核细胞增殖能力,促进其产生细胞外基质。     

周期性张应力对大鼠髁突软骨细胞Ⅱ型胶原表达的影响

目的:在成功构建髁突软骨细胞体外培养-力学刺激模型的基础上,探讨周期性张应力对髁突软骨细胞主要细胞外基质(Ⅱ型胶原)合成的影响.方法:本研究采用FX-5000T应力加载系统对体外培养的第3代大鼠髁突软骨细胞分别施加1h、6h、12h和24 h的周期性张应力,应力刺激强度为10％1 HZ.加力完成后即刻收集加力细胞,提取细胞总RNA反转录成cDNA,应用RT-PCR技术检测髁突软骨细胞主要细胞外基质Ⅱ型胶原(type-Ⅱ collagen,Col-Ⅱ)mRNA的表达变化情况.结果:与对照组(0h组)相比,加力1 h时Col-Ⅱ的表达增加,但无统计学意义;加力6h时Col-Ⅱ表达显著增加(P＜0.05);加力12h时Col-Ⅱ表达开始下降;当加力至24h时表达量显著降低(P＜0.05).结论:周期性张应力可以影响髁突软骨细胞主要细胞外基质的合成,在一定范围内随加力时间的延长基质合成逐渐增强;进一步延长加力时间,基质的合成受到明显抑制.     

白细胞介素-17对体外培养髓核细胞增殖和代谢的影响

目的:探究白细胞介素-17(interleukin-17,IL-17)对体外培养髓核细胞增殖和细胞代谢的影响。方法:髓核细胞取自经核磁共振影像确认需手术的退变椎间盘组织,建立体外培养体系。用2、5、10、15、20 ng/mL IL-17刺激髓核细胞72 h后,MTS法检测细胞增殖情况。用适当浓度IL-17刺激细胞48 h或96 h后,采用实时定量-PCR和免疫印迹方法检测基质和组织代谢相关基因的mRNA和蛋白表达。结果:IL-17刺激可以抑制体外培养髓核细胞的增殖,且15 ng/mL浓度的抑制作用最强。15 ng/mL IL-17刺激髓核细胞后,聚集蛋白聚糖(aggrecan,ACAN)和I型胶原(type I collagen,COL1A1)mRNA表达水平显著下降(P0.05),基质金属蛋白酶(matrix metalloproteinase-3,MMP3)、金属蛋白酶3组织抑制剂(tissue inhibitor of metalloproteinase-3,TIMP3)的mRNA表达水平显著上升(P0.05)。COL2A1 mRNA的表达下降,MMP13、含Ⅰ型血小板结合蛋白基序的结聚蛋白样金属蛋白酶(a disintegrin like and metalloproteinase with thrombospondin typeⅠ motifs-4,ADAMTS4)、ADAMTS5、TIMP1 mRNA的表达上升,但差异均不显著(P0.05)。IL-17刺激48 h时,COL1A1的蛋白水平明显下降(P=0.010),而ADAMTS5的蛋白水平显著上升(P=0.005)。但刺激96h时,COL1A1的蛋白表达下降,ADAMTS5的蛋白表达上升,但无显著差异(P0.05);COL2A1的蛋白表达水平显著下降(P=0.037)。结论:IL-17可抑制体外培养髓核细胞的增殖及代谢,在椎间盘的退变过程中可能发挥了重要的促进作用。     

人骨形态蛋白-2对椎间盘细胞蛋白多糖和Ⅱ型胶原的影响

目的研究人骨形态蛋白(human bone morphogenetic protein-2,hBMP-2)对体外培养人腰椎间盘髓核细胞Ⅱ型胶原和aggrecan的影响。方法人退变髓核细胞体外分离培养,通过免疫组织化学鉴定椎间盘细胞。利用ELISA法检测对照组和不同剂量hBMP-2(10ng/ml和100ng/ml)组Ⅱ型胶原和aggrecan的表达水平。用RT-PCR检测细胞Ⅱ型胶原和aggrecan的mRNA表达水平。结果加入hBMP-2后Ⅱ型胶原和aggrecan表达增加,并存在剂量依赖关系(P<0.01)。在第6天RT-PCR结果显示hBMP-2组aggrecan和Ⅱ型胶原mRNA的表达高于对照组,并且随剂量增高aggrecan和Ⅱ型胶原mRNA的表达量逐渐增加。结论hBMP-2可促进体外培养人腰椎间盘细胞合成代谢,Ⅱ型胶原和aggrecan表达量增加,并存在剂量依赖关系,提示hBMP-2可能对退变椎间盘具有修复功能。     

异位（过）表达PGRN抑制IL-1β引起的髓核细胞损伤

炎症因子IL-1β是引起髓核细胞功能异常的关键因素之一。颗粒体蛋白原（progranulin,PGRN）是一种多功能生长因子,在组织修复、炎症反应等过程中发挥重要作用,但其在髓核细胞中的作用尚不清楚。本研究以IL-1β诱导的髓核细胞炎性损伤模型为研究对象,探讨PGRN对IL 1β诱导的髓核细胞损伤的保护作用及其机制。基因转染结合MTT方法证明,与IL-1β处理的细胞比较,过表达PGRN可逆转IL-1β引起的原代培养的髓核细胞生长抑制,促进细胞增殖。TUNEL技术和流式细胞分析显示,PGRN抑制IL-1β诱导的髓核细胞凋亡。Western印迹和RT-qPCR方法揭示,与IL-1β处理的细胞相比,过表达PGRN显著上调聚蛋白聚糖（aggrecan）和II型胶原（collagen type II）的蛋白质表达,但下调基质金属蛋白酶-13（MMP-13）、分解素-金属蛋白酶ADAMTS-5的表达,同时抑制IL-1β诱导的炎性因子IL-6、IL-8和TNF-α的表达,说明PGRN可缓解IL-1β引起的炎性反应,并减少细胞外基质（ECM）相关蛋白质的降解。此外,过表达PGRN还可降低p65、p-IkB a和β-catenin的蛋白质表达水平,提示PGRN可抑制IL-1β下游TNF-α介导的NF-κB信号途径及β-catenin途径。总之,上述结果提示,过表达PGRN可通过抑制IL-1β诱导的炎性反应、髓核细胞凋亡及基质代谢紊乱,缓解IL-1β诱导的髓核细胞损伤;PGRN的这种抗炎、抗基质降解作用可能与PGRN参与调控NF-κB和β-catenin信号途径有关。     

MMP-2、MMP-3、MMP-9、TIMP-3及Col-Ⅱ因子在兔软骨细胞损伤后的表达变化

检测MMP-2、MMP-3、MMP-9、TIMP-3及Ⅱ型胶原细胞外基质因子在正常兔关节软骨细胞和划伤后不同时间点的表达变化。在无菌条件下获取兔膝关节软骨细胞,原代体外培养软骨细胞,六孔板内制备细胞损伤模型。用显微镜观察正常细胞和损伤后1 d、3 d和7 d 3个时间点的软骨细胞增殖情况。采用实时PCR检测正常软骨细胞和损伤后1 d、3 d和7 d 3个时间点的基质金属蛋白酶-2、3和9,基质金属蛋白酶抑制物-3及Ⅱ型胶原的m RNA的表达水平。成功分离软骨,经原代培养后成功建立损伤细胞模型。MMP-2损伤后第1天与正常组相比升高,第3天时下降,第7天明显水平最高。与正常组相比,MMP-3在细胞损伤后第1天表达明显下降,随后第3天逐渐下降,第7天与第3天未见明显变化。MMP-9划伤后第1天比正常组升高,第3天上升至最高水平,第7天下降。TIMP-3基因在损伤后第1天与正常组相比明显下降,随后第3天稍有升高,第7天水平最低。Ⅱ型胶原划伤后第1天与正常组相比明显升高,随后第3天呈下降趋势接近于正常组,第7天又呈上升趋势。MMP-2、MMP-3、MMP-9、TIMP-3因子和Ⅱ型胶原在细胞损伤后的不同时间点有不同的表达行为,这可为调节细胞外基质基因治疗关节软骨损伤选择合适的靶基因和时间窗提供实验依据。     

低强度周期性静水压力对人膝关节软骨细胞的影响

目的:探讨低强度周期性静水压力对体外培养的人膝关节软骨细胞增殖、凋亡,以及细胞Ⅱ型胶原分泌表达的影响。方法:体外酶消化法分离培养成人膝关节正常软骨细胞,将培养的第3代软骨细胞分为两组:正常对照组、3.0MPa组压力实验组,应用多功能恒温体外细胞培养中高压静水压力加载装置加载低强度周期性压力,共5d,每天2h。Ⅱ型胶原免疫组织化学染色法和甲苯胺蓝染色法鉴定软骨细胞,流式细胞术检测细胞凋亡,四甲基偶氮唑蓝(MTT)法绘制细胞生长曲线,qRT-PCR、Western-Blot检测Ⅱ型胶原的分泌和表达。结果:软骨细胞Ⅱ型胶原免疫组织化学染色和甲苯胺蓝染色均显示为阳性。与正常对照组相比,3.0MPa组表现出促进软骨细胞增殖,抑制细胞凋亡,且Ⅱ型胶原的合成分泌明显升高(P0.05)。结论:通过体外模拟人生理情况下较低强度(3.0MPa)的周期性静水压力对人软骨细胞增殖、凋亡水平及周围基质分泌合成功能的影响,初步证实了较低强度压力有助于软骨自我修复和自身保护作用的发挥。     

High osmolality activates the G1 and G2 cell cycle checkpoints and affects the DNA integrity of nucleus pulposus intervertebral disc cells triggering an enhanced DNA repair response

Nucleus pulposus intervertebral disc cells experience a broad range of physicochemical stimuli in their native environment including osmotic fluctuations. Here we show that hyperosmotic treatment reduced nucleus pulposus cells’ proliferation by activating the G2 and G1 cell cycle checkpoints. p38 MAPK was found to participate in the manifestation of the G2 arrest under conditions of increased osmolality, since inhibition of its activity by SB203580 released the cells from G2 phase into mitosis. High osmolality resulted in the ATM-mediated phosphorylation of p53 on Ser15, the up-regulation of p21^WAF1 and the hypophosphorylation of the retinoblastoma protein in accordance to the observed G1 arrest. siRNA knocking down of p53 inhibited the expression of p21^WAF1 while maintaining the hyperphosphorylated form of the retinoblastoma protein and thus abrogated the G1 arrest observed under hyperosmotic conditions. Comet assay revealed that high osmolality provoked DNA damage to nucleus pulposus cells. Several previous reports have shown that renal cells become unable to sense and repair DNA damage under conditions of increased osmolality. On the contrary, nucleus pulposus cells residing within a hyperosmotic environment clearly preserved their ability to sense newly introduced DNA damage, as confirmed by the reactivation of p53 by ionizing radiation, retained the MRN complex in the nucleus and phosphorylated H2A.X on Ser139. H2A.X phosphorylation was attenuated in cells persistently experiencing hyperosmotic stress which, combined with the concurrent reduction in comet tails’ length, indicated an active DNA repair machinery. Even more, when the DNA repair efficiency of nucleus pulposus cells was directly measured by a host cell reactivation of luciferase activity assay, it was found to be significantly increased under hyperosmotic pressure. Finally, p53 depletion of nucleus pulposus cells by siRNA enhanced and prolonged H2A.X phosphorylation, attributing to p53 a regulatory role in the DNA repair pathway induced by increased osmolality.     

Phenotypic characteristics of the nucleus pulposus: expression of hypoxia inducing factor-1, glucose transporter-1 and MMP-2

Attempts to study the biology of the nucleus pulposus have been limited in scope due to the low rates of cell proliferation, difficulties in maintaining viable disc cells in culture and the absence of a clearly defined phenotype. The major objective of this communication is to construct a phenotypic signature for cells of the nucleus pulposus that is based on the hypothesis that in response to restriction on oxygen and nutrient flux, there is expression of HIF-1, GLUT-1 and MMP-2. Nucleus pulposus, as well as annulus fibrosus and cartilage of the vertebral end plates, was collected from rat spinal units. Western blot analysis and immunohistochemistry clearly showed that there was a significant level of expression of the HIF-1 beta isoform in the nucleus pulposus; HIF-1 beta was present at lower levels in cells of the annulus and the end plate. In contrast to HIF-1 beta, HIF-1 alpha was expressed only in the nucleus pulposus. This isoform was absent from both the cartilage end plate and annulus. We detected HIF-1 alpha immunohistochemically in the nucleus pulposus; however, the staining was light and diffuse. Cells of the nucleus pulposus expressed GLUT-1; in contrast, when probed by Western blot analysis the annulus and cartilage were negative for this protein. Western blot analysis also showed that in the nucleus pulposus the level of MMP-2 was high when compared to the adjacent tissues. We suggest that the differential expression of the two HIF isoforms, and GLUT-1 and MMP-2, provides a phenotypic signature that permits cells of the nucleus pulposus to be distinguished from neighboring tissues. Moreover, the presence of these isoforms provides evidence that cells of the disc respond to hypoxia and nutrient stress by upregulating stress-responsive genes.     

Disc mechanics with trans-endplate partial nucleotomy are not fully restored following cyclic compressive loading and unloaded recovery

Mechanical function of the intervertebral disc is maintained through the interaction between the hydrated nucleus pulposus, the surrounding annulus fibrosus, and the superior and inferior endplates. In disc degeneration the normal transfer of load between disc substructures is compromised. The objective of this study was to explore the mechanical role of the nucleus pulposus in support of axial compressive loads over time. This was achieved by measuring the elastic slow ramp and viscoelastic stress-relaxation mechanical behaviors of cadaveric sheep motion segments before and after partial nucleotomy through the endplate (keeping the annulus fibrosus intact). Mechanics were evaluated at five conditions: Intact, intact after 10,000 cycles of compression, acutely after nucleotomy, following nucleotomy and 10,000 cycles of compression, and following unloaded recovery. Radiographs and magnetic resonance images were obtained to examine structure. Only the short time constant of the stress relaxation was altered due to nucleotomy. In contrast, cyclic loading resulted in significant and large changes to both the stiffness and stress relaxation behaviors. Moreover, the nucleotomy had little to no effect on the disc mechanics after cyclic loading, as there were no significant differences comparing mechanics after cyclic loading with or without the nucleotomy. Following unloaded recovery the mechanical changes that had occurred as a consequence of cyclic loading were restored, leaving only a sustained change in the short time constant due to the trans-endplate nucleotomy. Thus the swelling and redistribution of the remaining nucleus pulposus was not able to fully restore mechanical behaviors. This study reveals insights into the role of the nucleus pulposus in disc function, and provides new information toward the potential role of altered nucleus pulpous function in the degenerative cascade.     

NF-κB信号通路参与高糖在椎间盘退行性变中影响及其作用的研究

目的:近来研究发现,椎间盘退变与代谢性疾病,尤其是与糖尿病具有明显的相关性,但具体机制尚未有深入研究。本实验拟探究高糖微环境诱导椎间盘退行性变及其对NF-κB信号通路的影响,为进一步揭示高糖诱导椎间盘髓核细胞退变的机制提供研究基础,为延缓、阻止糖尿病椎间盘退变和治疗糖尿病相关腰痛疾病带来新的策略和方法。方法:1、高糖微环境与IVDD的关系:使用5.5 mmol/L、15 mmol/L、30 mmol/L、100 mmol/L不同浓度葡萄糖培养基培养髓核细胞,RT-PCR检测髓核细胞MMP-3、MMP-13、Aggrecan、CollagenII的表达;2、NF-κB信号通路参与高糖微环境调控IVDD进展:Bay11-7082抑制NF-κB信号通路激活,再使用RT-PCR、Western Blot检测髓核细胞MMP-3、MMP-13、Aggrecan、CollagenII和NF-κB的表达。结果:RT-PCR检测显示,在不同葡萄糖浓度下,Aggrecan、CollagenII随浓度升高表达减少,MMP-3、MMP-13随浓度升高表达增加。RT-PCR、Western Blot检测显示,使用Bay11-7082可使高糖组中Aggrecan、CollagenII表达增加,MMP-3、MMP-13表达减少。结论:高糖微环境诱导椎间盘退行性变发病,且NF-κB信号通路参与高糖微环境诱导椎间盘退行性变发病。     

Versican G3 domain enhances cellular adhesion and proliferation of bovine intervertebral disc cells cultured in vitro

The functional role of versican in influencing intervertebral disc cell adhesion and proliferation was analyzed in bovine intervertebral disc. We have previously demonstrated the C-terminal globular G3 (or selectin-like) domain of versican to influence mesenchymal chondrogenesis and fibroblast proliferation in vitro. For this study, a versican G3 expression construct was generated to examine the role of the G3 domain of versican. Nucleus pulposus and annulus fibrosus cells were isolated from adult bovine caudal discs using sequential enzymatic digestion and versican expression characterized by RT-PCR. In cell proliferation assays, we observed that there was greater cellular proliferation in the presence of versican G3 for both disc cell types. The higher proliferation rate of annulus fibrosus cells when compared to nucleus pulposus cells seeded in monolayer supports heterogeneity of intervertebral disc cell populations. The presence of versican G3 construct enhanced the adhesion of isolated nucleus pulposus and annulus fibrosus cells approximately 4 to 6 fold, respectively. Cellular adhesion was greater in the presence of versican G3 in a dose dependent manner. G3 product was purified using affinity columns, and the purified G3 also enhanced cell adhesion.     

Transcriptional profiling of bovine intervertebral disc cells: implications for identification of normal and degenerate human intervertebral disc cell phenotypes

Introduction  

Nucleus pulposus (NP) cells have a phenotype similar to articular cartilage (AC) cells. However, the matrix of the NP is clearly different to that of AC suggesting that specific cell phenotypes exist. The aim of this study was to identify novel genes that could be used to distinguish bovine NP cells from AC and annulus fibrosus (AF) cells, and to further determine their expression in normal and degenerate human intervertebral disc (IVD) cells.     

Hyaluronan injection in murine osteoarthritis prevents TGFbeta 1-induced synovial neovascularization and fibrosis and maintains articular cartilage integrity by a CD44-dependent mechanism

Introduction

The goals of this study were to examine the oxemic regulation of Wnt signaling to explore whether Wnt signaling accelerates the age-related degeneration of nucleus pulposus cells, and if so, to define the mechanism underlying this effect. We investigated the expression of Klotho, a newly identified antiaging gene, and whether its regulation is attributable to the suppression of Wnt signaling.

Methods

Rat nucleus pulposus cells were cultured under normoxic (21% O₂) or hypoxic (2% O₂) conditions, and the expression and promoter activity of Wnt signaling and Klotho were evaluated. The effect of Klotho protein was examined with transfection experiments, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, senescence-associated ??-galactosidase staining, and cell-cycle analysis. To determine the methylation status of the Klotho promoter region, bisulfite genomic sequencing analysis was performed. Its relation with the activation of Wnt signaling was assessed. We also examined whether the expression of Klotho could block the effects of pathological Wnt expression in nucleus pulposus cells.

Results

Nucleus pulposus cells exhibited increased ??-catenin mRNA and protein under the hypoxic condition. Klotho protein was expressed in vivo, and protein and messenger RNA expression decreased under the hypoxic condition. Klotho treatment decreased cell proliferation and induced the quiescence of nucleus pulposus cells. In addition, Klotho treatment inhibited expression of ??-catenin gene and protein compared with untreated control cells.

Conclusions

These data indicate that Wnt signaling and Klotho form a negative-feedback loop in nucleus pulposus cells. These results suggest that the expression of Klotho is regulated by the balance between upregulation and downregulation of Wnt signaling.