流体剪切力对破骨细胞的影响

骨组织受到成骨细胞成骨作用和破骨细胞溶骨作用共同影响。与成骨细胞和骨细胞不同,破骨细胞起源于造血干细胞,由单核巨噬细胞发育而来,具有吞噬功能,能对多种刺激因素产生效应,其中机械刺激是始终存在的影响方式。机械刺激诱导的成骨细胞的正性调节对于骨生成、骨修复有至关重要的作用,而破骨细胞在这些方面的效应也十分关键。流体剪切力作为骨组织内机械刺激的一种常见形式,作用于成骨细胞和骨细胞的时候,通过对Ca2+、前列腺素、NO、RANKL和OPG等信号因子的影响,表现出介导破骨细胞迁移、分化、吸收和生存维持等现象的功能,这承载了骨代谢必不可少的一部分。同时这些因子相互交错,表现出复杂信息网络及阶段特异性。但总的来说,人们对流体剪切力调节破骨细胞生理及病理功能具体信号传导的了解还不是很深入,需要用更多的研究来阐明流体剪切力和破骨细胞之间的关系。本文就流体剪切力对破骨细胞相关分子信号影响做一综述,简要展示流体剪切力影响破骨细胞的相关机理。     

流体剪切力对成骨细胞影响的研究进展

骨是一个富含多孔的组织,被组织间液持续灌流,由于受血压和活体外机械装载的驱使,组织间液经过骨组织中的腔隙、小管网和骨内膜表面的骨内层产生明显的流体剪切力（fluid shear stress,FSS）。大量研究表明,成骨细胞是其中重要的感受与效应细胞,可通过力敏感离子通道、G蛋白与酪氨酸激酶、整合素受体与细胞骨架等多种途径感受体内外力学刺激,并将力学刺激信号转化为细胞生物化学信号,介导力相关敏感基因表达,合成各种酶类等活性物质,激活信号网络级联反应,     

一氧化氮与骨代谢

一氧化氮与骨代谢王立平党耕町近几年来，一氧化氮（ｎｉｔｒｉｃｏｘｉｄｅ，ＮＯ）倍受医学界的重视，被视为心血管、神经及免疫系统中重要的信号传导递质［１，２］。多种细胞具有生成ＮＯ的能力。随着对ＮＯ研究的深入和推广，现发现ＮＯ同骨细胞的功能似乎很密切，内...     

锂对骨免疫调控作用的研究进展

随着对骨骼系统研究的深入,骨骼系统和免疫系统之间相互作用的复杂性已得到学者广泛认可。免疫系统可调控骨组织微环境稳态,维持骨改建的动态平衡,而骨改建过程中的细胞也可调控免疫细胞的极化和功能。锂不仅是一种公认的治疗双向情感障碍等精神类疾病的常用药物,还可通过多种途径参与机体免疫调节,实现骨组织再生。该文拟就锂在骨免疫中的作用及在骨免疫中的调控机制进行综述。     

骨改建的分子生物学进展

骨改建是成骨细胞和破骨细胞相互作用的过程，但关于骨改建的启动、骨改建过程中各种生长和调节因子和何影响成骨细胞和破骨细胞的化和功能一直不清楚。近１０年来细胞培养和基因敲除实验发现和证实了一些对骨改建起关键作用的分子和分子机制。     

Cbfa1基因调节骨形成与骨吸收的研究进展

骨的形成与吸收是一个涉及众多的基因和生长因子的复杂过程,凡可使骨形成下降和骨吸收增加的因素都会促进骨质疏松的发生.Cbfa1是成骨细胞分化和成熟的特异性转录因子,研究发现Cbfa1可通过促进骨形成和抑制骨吸收,对骨质疏松的发生、发展起到抑制作用,因此,我们期望随着Cbfa1基因研究的深入将为防治骨质疏松提供新思路.     

骨保护蛋白配体与骨吸收

骨终生都在进行改建 (Ｒｅｍｏｄｅｌｉｎｇ) ,通过持续不断的骨形成和骨吸收来维持其形态与功能。这一生理过程涉及到成骨细胞 (ＯＢ)和破骨细胞 (ＯＣ)。ＯＣ来自于造血的祖细胞(ｐｒｏｇｅｎｉｔｏｒ)或造血性单核 /巨噬细胞前体 (ｐｒｅｃｕｒｓｏｒ)。这种前体细胞在骨髓微环境和成骨细胞系分泌的细胞因子的作用下 ,在骨吸收的位点分化为成熟的ＯＣ[1～ 3] 。然而从ＯＣ前体分化为成熟的ＯＣ的确切机制目前还不清楚 ,直至最近骨保护蛋白配件 (Ｏｓｔｅｏｐｒｏｔｅｇｅｒｉｎｌｉｇａｎｄ ,ＯＰＧＬ)的发现 ,才使人们对这一问题的认识…     

胆固醇对骨代谢影响的研究进展

正常骨代谢是动态调节的周期过程,破骨细胞负责的骨吸收与成骨细胞负责的骨形成相互偶联维持动态平衡.当骨形成和骨吸收的动态平衡被破坏时,就会引起骨量丢失及相关骨病.流行病学证据表明,胆固醇会抑制或促进骨代谢,这取决于胆固醇的种类.胆固醇及其代谢产物通过调节成骨细胞和破骨细胞的分化及活化来影响骨代谢的动态平衡.本文就胆固醇对...     

microRNA在骨发育和形成过程中作用的研究进展

microRNA是一类通过抑制翻译和降解mRNA来调控基因表达的非编码的单链RNA,参与细胞增殖、分化、凋亡等过程。其中一些microRNA作用于特定靶目标,调节成骨细胞、破骨细胞和软骨细胞的增殖分化,进而影响骨的新陈代谢,参与骨的发育和形成。     

间隙液流体剪切力在骨细胞机械力传导过程中的作用

机械负荷是骨结构和骨量重要调节因素，已经证明增加外源性负荷能促进骨形成而移去负荷能使骨量减少。近年来，对骨细胞感知其周围机械环境变化的分子机制理解有了很大进步，其中细胞间隙液流体剪切力在机械力信号传导中发挥了重要的作用。现将骨细胞感知间隙液流体剪切力可能的分子机制及这种生物物理信号在组织工程中的应用综述如下。     

流体剪切应力促进成骨细胞增殖的机制

成骨细胞是骨组织中重要的的刺激感受细胞和效应细胞,参与多种力学刺激下骨的修复及重建。流体剪切应力是人体内骨组织受到的最直接的力学刺激,已有大量研究证明流体剪切应力可以通过激活Wnt信号通路、BMP-Smad依赖性信号通路或BMP-非Smad依赖性信号通路促进成骨细胞增殖分化。近年来,越来越多的研究发现流体剪切应力还可以通过激活ERK5信号通路、PI3K/AKT激酶信号通路等途径抑制成骨细胞凋亡,这为流体剪切应力促进成骨细胞增殖提供了一个新的研究方向。本文就近年来流体剪切应力促进成骨细胞增殖的影响机制作一综述,希望能为骨科相关疾病的防治及研究提供参考。     

流体剪切应力对成骨细胞信号转导机制的影响

机械应力在骨的生长、重建过程中起着十分重要的作用.应力作用于骨组织对骨细胞、成骨细胞等应力感受细胞产生牵张应力和流体剪切应力(FSS),进而影响细胞内相关基因的表达,其中FSS占主导作用.FSS引起骨细胞分子活动的具体机制尚不明确,细胞膜上的应力敏感离子通道、整合素-细胞骨架复合体、G蛋白、蛋白激酶介导通路、RhoA/Rho激酶(ROCK)通路,以及间隙连接/间隙连接蛋白Cx43半通道结构,可能在力学信号转导过程中起重要作用.     

适宜组织工程化骨构建的流体剪切力和物质转运速度的研究

目的 探讨适宜组织工程化骨构建的流体剪切力和物质转运速度.方法 对接种人骨髓间质干细胞的多孔β-磷酸三钙支架进行灌注培养.灌流量相同时,对支架上的细胞分别施加1×、2×及3×的流体剪切力;流体剪切力相同时,分别给予3ml/min、6 ml/min和9 ml/min的灌注.细胞增殖采用MTT法,通过检测碱性磷酸酶(alkalilinphosphatase,AKP)活性、骨桥蛋白(osteopontin,OP)、骨钙素(osteocalcin,OC)分泌及细胞外基质的矿化评价组织工程化骨的构建.通过计算流体动力学得出流体剪切力和物质转运速度.结果 灌流量相同时,剪切力2×组细胞增殖活性最高;2×和3×组AKP活性及OC分泌高于1×组;第28天时,3×组矿化基质最多.流体剪切力相同时,6 ml/min组AKP活性最高;第28天时,3 ml/min组OC分泌最高,矿化基质最多.灌流量相同时,流体剪切力分别为0.004～0.007 Pa、0.009～0.013 Pa和0.013～0.018 Pa;流体剪切力相同时,物质转运速度分别为0.267～0.384 mm/s、0.521～0.765mm/s和0.765～1.177 mm/s.结论 利用接种人骨髓间质干细胞的β-磷酸三钙支架构建组织工程化骨时,0.013～0.018 Pa的流体剪切力及0.267～0.384 mm/s的物质转运速度是适宜的.

Abstract：

Objective To explore the optimum flow shear stress and mass transport for the construction of tissue-engineered bone.Methods The β-tricalcium phosphate (β-TCP) scaffolds seeded with human bone marrow-derived mesenchymal stem cells (HBMMSCs) were cultured in perfusion bioreactor.When the same flow rate was applied,the flow shear stress was separately 1×,2× and 3×.When the same flow shear stress was applied,the flow rates were separately 3 ml/min,6 ml/min and 9 ml/min.Cell proliferation was measured by MTT method.The construction of tissue-engineered bone was evaluated by measuring alkaline phosphatase (AKP) activity,secretion of osteopontin (OP) and osteocalcin (OC),and the mineralization of extracellular matrix (ECM).The flow shear stress and the mass transport were obtained using computational fluid dynamics.Results When the flow rate was same,the most cell proliferation was found in 2× group.The AKP activity and secretion of OC was higher in 2× and 3× groups than in those in 1× group.After 28days,the highest amount of mineralization of ECM was found in 3× group.When the flow shear stress was same,the AKP activity was highest in 6 ml/min group.After 28 days,secretion of OC and formation of mineralized ECM was highest in 3 ml/min group.When the flow rate was same,the flow shear stress was separately 0.004-0.007 Pa,0.009-0.013 Pa and 0.013-0.018 Pa.When the flow shear stress was same,the flow rate was separately 0.267-0.384 mm/s,0.521-0.765 mm/s and 0.765-1.177 mm/s.Conclusion When the tissue-engineered bone was constructed,0.013-0.018 Pa flow shear stress and 0.267-0.384 mm/s mass transport velocity could improve the construction of the tissue-engineered bone in vitro.     

Effect of human amniotic fluid on bone healing

BACKGROUND: Bone healing continues to pose challenges for researchers and clinicians working in the field of plastic surgery. Complete bone regeneration cannot be obtained in critical size osseous defects without the application of osteogenic or osteoinductive bone material. In this study, we hypothesized that because extracellular matrix components are known to play a major role in the first steps of healing during bone or injury healing and because hyaluronic acid as chondroitin sulfate is recognized as an osteogenic compound without osteoinductive activity, human amniotic fluid, which contains high concentrations of hyaluronic acid, gyaluronic acid -stimulating activator, and other factors, might accelerate bone healing when applied subperiosteally to rabbit calvarial defects. MATERIALS AND METHODS: We created 20 calvarial defects in 10 12-week-old New Zealand white rabbits who were divided into 2 groups. Group 1 defects were instilled with human amniotic fluid, whereas the group with contralateral defects, i.e., group 2, were given with same amount of normal saline solution. We then measured the density of the bone that formed over the defects using computed tomography at the third, fourth, fifth, and sixth weeks postoperatively. After this period, the defects were harvested for histopathologic evaluation. RESULTS: The defects from group 1, which were treated with human amniotic fluid, showed significantly higher ossification than the group 2 defects, which were instilled with saline solution. Histological examination at 6 weeks postoperatively revealed that the defects treated with human amniotic fluid (group 1) had superior ossification compared with the control group defects (group 2). CONCLUSION: Because of its positive effects on bone healing and also because of its ability to be stored in deep freeze if made cell-free, human amniotic fluid would appear to be a useful adjunct in the treatment of bone healing.     

周期性流体剪切力对成骨细胞增殖影响机制的实验研究

[目的]体外观察周期性流体剪切力(cFSS)作用下成骨细胞增殖情况的变化及细胞外信号调节激酶5( ERK5)在这一过程中的作用,探讨周期性流体剪切力对成骨细胞增殖的影响及其机制.[方法]体外运用5-溴-2'-脱氧尿苷( BrdU)标记成骨细胞(MC3T3 - E1)核,随机分为A、B、C、D共4组,A组为空白对照组,B和C组MC3T3- E1细胞通过流体剪切力加载装置施加周期性剪切力,C、D组MC3T3- E1细胞加入ERK5特异性阻断剂BIX02189,运用免疫荧光化学技术及IPP图像分析软件对各组成骨细胞增殖情况进行分析.[结果]A组细胞处于正常增殖状态,B组细胞增殖的阳性率与A组比较提高了200％ (P ＜0.05),ERK5活化量(累积光密度值)增加了30％ (P ＜0.05);C组细胞增殖情况比A组提高了40％ (P ＜0.05),而ERK5的活化量却无显著差异(P＞0.05);D组阳性率与A组比较降低了70％ (P ＜0.05),而ERK5的活化量降低了30％ (P ＜0.05).[结论]周期性流体剪切力促进成骨细胞增殖;ERK5在介导周期性流体剪切力促进成骨细胞增殖方面起着重要的作用.     

Oscillatory fluid flow-induced shear stress decreases osteoclastogenesis through RANKL and OPG signaling

Physical activity creates deformation in bone that leads to localized pressure gradients that drive interstitial fluid flow. Due to the cyclic nature of the applied load, this flow is oscillatory by nature. Oscillatory fluid flow (OFF) may lead to positive bone remodeling through effects on both osteoblasts and osteoclasts but its effect on osteoclastogenesis is poorly understood. In this study, the effects of OFF on expression of receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG), two important regulators of osteoclast differentiation, were investigated. In addition, its effect on osteoclast formation was quantified. ST-2 murine bone marrow stromal cells were plated on glass slides and cultured with 1,25-dihydroxyvitamin D(3) to express RANKL. Cells were exposed to various durations of OFF resulting in a peak shear stress of 1 Pa. Time course and dose-response studies were performed and real-time RT-PCR was used to quantify levels of RANKL, OPG mRNA. ST-2 cells exposed to OFF were also co-cultured with RAW 264.7 monocytes and osteoclast number quantified. Decrease in RANKL/OPG was maximal immediately after end of flow and there existed a significant increase in OPG and decrease in RANKL with increasing load duration of up to 2 h. OFF resulted in a decrease in osteoclast formation by ST-2 cells co-cultured with RAW 264.7 cells compared to co-culture of control (non-loaded) ST-2 cells with RAW 264.7 cells. These results suggest that indeed OFF is a potent regulator of bone remodeling, and that shift towards positive bone remodeling mediated by loading-induced fluid flow may occur via suppression of the formation of osteoclasts.     

血管内皮生长因子在骨折修复过程中血管生成的促进作用

目的观察血管内皮生长因子(VEGF)在骨折修复过程中对骨折端微血管密度(MVD)的影响，探讨VEGF在骨折端血管生成中的作用。方法用168只大白鼠制作股骨骨折模型，随机分为VEGF组、拮抗VEGF组、对照组，用免疫组织化学分别测定伤后不同时间骨折端MVD的变化。结果应用外源性VEGF后。骨折端MVD明显增加；拮抗VEGF组，骨折端MVD明显下降；对照组MVD低于VEGF组，但高于拮抗VEGF组。结论VEGF在骨折修复过程中，对血管生成具有重要作用，并可能作为一种重要细胞因子参与和调节了骨折修复过程。     

Osteocyte physiology and response to fluid shear stress are impaired following exposure to cobalt and chromium: Implications for bone health following joint replacement

The effects of metal ion exposure on osteocytes, the most abundant cell type in bone and responsible for coordinating bone remodeling, remain unclear. However, several studies have previously shown that exposure to cobalt (Co²⁺) and chromium (Cr³⁺), at concentrations equivalent to those found clinically, affect osteoblast and osteoclast survival and function. In this study, we tested the hypothesis that metal ions would similarly impair the normal physiology of osteocytes. The survival, dendritic morphology, and response to fluid shear stress of the mature osteocyte‐like cell‐line MLO‐Y4 following exposure to clinically relevant concentrations and combinations of Co and Cr ions were measured in 2D‐culture. Exposure of MLO‐Y4 cells to metal ions reduced cell number, increased dendrites per cell and increased dendrite length. We found that combinations of metal ions had a greater effect than the individual ions alone, and that Co²⁺ had a predominate effect on changes to cell numbers and dendrites. Combined metal ion exposure blunted the responses of the MLO‐Y4 cells to fluid shear stress, including reducing the intracellular calcium responses and modulation of genes for the osteocyte markers Cx43 and Gp38 , and the signaling molecules RANKL and Dkk‐1 . Finally, we demonstrated that in the late osteoblasts/early osteocytes cell line MLO‐A5 that Co²⁺ exposure had no effect on mineralization, but Cr³⁺ treatment inhibited mineralization in a dose‐dependent manner, without affecting cell viability. Taken together, these data indicate that metal exposure can directly affect osteocyte physiology, with potential implications for bone health including osseointegration of cementless components, and periprosthetic bone remodeling. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1716–1723, 2017.