成骨细胞相关因子在骨代谢中的作用

成骨细胞是骨形成的主要功能细胞,负责骨基质的合成、分泌和矿化。骨组织始终在不断地进行着重建,骨重建过程包括破骨细胞贴附在旧骨区域,分泌酸性物质溶解矿物质,分泌蛋白酶消化骨基质,形成骨吸收陷窝,而后成骨细胞移行至被吸收部位,分泌骨基质,骨基质矿化而形成新骨。破骨与成骨过程的平衡维持着人体正常骨量的代谢。     

成骨细胞和破骨细胞衰老改变及其在增龄性骨丢失中的作用

背景：认识增龄过程中成骨细胞和破骨细胞变化规律，特别是高龄人群成骨细胞和破骨细胞的生物学特点，对骨质疏松有效合理的防治具有十分重要的意义。目的：回顾关于成骨细胞和破骨细胞数量和活性增龄变化的实验及临床研究结果，明确增龄过程中成骨细胞和破骨细胞的变化规律和衰老特点。数据来源：1995／2003 PubMed，2002／2004年万方数据库，本实验室研究结果。数据提取：PubMed 16篇，万方数据库1篇，本实验室数据。主要观察指标：细胞数量、酶活性、基因表达水平。结果：高龄人群成骨细胞骨形成作用和破骨细胞骨吸收作用对骨骼的影响都逐渐下降，但表现出不同的特点。①骨形成功能持续降低，主要表现为：成骨细胞分裂增生能力降低、基质合成减少、对钙调激素的敏感性降低。这些变化与骨髓中前体细胞的快速减少有关，使高龄人群骨骼中成骨细胞群由于缺乏新生细胞的不断补充而功能退化。②骨吸收功能短暂激活，主要表现为：破骨细胞数量一度增加，而其泌酸和蛋白酶功能基本得以保持。③成骨细胞调节能力降低，主要表现为成骨细胞中RANKL和OPG表达失偶联。结论：破骨细胞激活的机制和破骨细胞二次活跃产生不同骨平衡的意义值得探讨。作为建议，作提倡在基础领域重视骨髓微环境中前体细胞分化增殖的研究。     

骨重建与能量代谢共调节机制的研究进展

骨骼是一个动态活性组织,它通过持续性重塑来维持其矿化平衡及自身的结构完整.在骨重塑的过程中,骨骼能协调成骨细胞、骨细胞和破骨细胞之间的活性,保持着骨重塑过程的动态耦联平衡,其中成骨细胞（骨形成功能）和破骨细胞（骨吸收功能）在骨重塑过程中起关键作用.由于骨组织破坏以及随后骨形成均需要能量消耗,故已有学者提出骨重建与能量代谢共调节假说[1,2],然而其具体的机制目前尚未阐明.本综述旨在从骨骼内分泌角度,分析骨重建与能量代谢共调节机制的研究进展.     

成骨细胞和破骨细胞衰老改变及其在增龄性骨丢失中的作用

背景认识增龄过程中成骨细胞和破骨细胞变化规律,特别是高龄人群成骨细胞和破骨细胞的生物学特点,对骨质疏松有效合理的防治具有十分重要的意义.目的回顾关于成骨细胞和破骨细胞数量和活性增龄变化的实验及临床研究结果,明确增龄过程中成骨细胞和破骨细胞的变化规律和衰老特点.数据来源1995/2003 PubMed,2002/2004年万方数据库,本实验室研究结果.数据提取PubMed 16篇,万方数据库1篇,本实验室数据.主要观察指标细胞数量、酶活性、基因表达水平.结果高龄人群成骨细胞骨形成作用和破骨细胞骨吸收作用对骨骼的影响都逐渐下降,但表现出不同的特点.①骨形成功能持续降低,主要表现为成骨细胞分裂增生能力降低、基质合成减少、对钙凋激素的敏感性降低.这些变化与骨髓中前体细胞的快速减少有关,使高龄人群骨骼中成骨细胞群由于缺乏新生细胞的不断补充而功能退化.②骨吸收功能短暂激活,主要表现为破骨细胞数量一度增加,而其泌酸和蛋白酶功能基本得以保持.③成骨细胞调节能力降低,主要表现为成骨细胞中RANKL和OPG表达失偶联.结论破骨细胞激活的机制和破骨细胞二次活跃产生不同骨平衡的意义值得探讨.作为建议,作者提倡在基础领域重视骨髓微环境中前体细胞分化增殖的研究.     

Wnt/β-catenin信号通路在骨重建中的作用研究进展

<正>骨重建包括骨吸收及其耦联的骨形成两方面,在正常情况下,成骨细胞介导的骨形成和破骨细胞介导的骨吸收维持动态平衡。Wnt/β-catenin信号通路在骨重建过程中起到重要的作用,与成骨细胞分化、增殖和骨形成密切相关,并通过不同途径影响破骨细胞及骨细胞的功能,现就Wnt/β-catenin信号通路在骨重建过程中的作用作一综述。Wnt/β-catenin信号通路,进化保守,在胚胎发育、器官形     

骨代谢过程中雌激素的影响与作用

背景:绝经后女性出现的骨质疏松是一种全身性的骨代谢障碍疾病,与雌激素水平的下降密切相关。目的:分别从雌激素对破骨细胞和成骨细胞的作用综述了雌激素对骨代谢的影响。方法:由第一作者使用计算机检索Medline数据库,全国期刊全文数据库(CNKI),检索词为"estrogen,osteoporosis,bone metabolism,osteoblasts,osteoclasts,osteogenesis,bone resorption"和"雌激素,骨质疏松症,骨代谢,成骨细胞,破骨细胞,骨生成,骨吸收"。从雌激素对破骨细胞、成骨细胞影响两个方面进行总结。共检索到216篇文章,按纳入和排除标准对文献进行筛选,共纳入48篇文章。结果与结论:雌激素水平下降破坏了体内成骨与破骨之间的动态平衡,从而导致骨质的吸收,骨量的减少、脆性增加、增加了骨折的风险。雌激素对成骨细胞、破骨细胞均产生调节作用,进而促进骨形成、抑制骨吸收,维持骨代谢平衡。     

多发性骨髓瘤溶骨性病变机制的研究进展

溶骨性病变是多发性骨髓瘤常见临床表现之一。本文近几年关于其发病机制的研究和一综述，从中可以看出，骨形成与骨吸收比例的失衡是其直接原因，破骨细胞、成骨细胞及有关细胞因子在这一过程中扮演重要角色。     

护骨素及相关因子与多发性骨髓瘤骨病的关系

骨质重建是骨吸收和骨形成耦联的动态平衡过程，破骨细胞是骨吸收的效应细胞。多发性骨髓瘤表现特征性溶骨病变，其机制与骨髓微环境中调节破骨细胞功能的细胞因子生理平衡破坏有关，护骨素、核因子κB受体活化因子及其配体是对破骨细胞生成起决定作用的关键因素，也是治疗多发性骨髓瘤骨病潜在的靶目标。     

多发性骨髓瘤溶骨性病变机制的研究进展

溶骨性病变是多发性骨髓瘤常见临床表现之一。本文就近几年关于其发病机制的研究作一综述,从中可以看出,骨形成与骨吸收比例的失衡是其直接原因:破骨细胞、成骨细胞及有关的细胞因子在这一过程中扮演重要角色。     

小鼠骨髓内破骨细胞诱导形成的实验观察

目的:建立骨髓间充质干细胞诱导培养成为破骨细胞的培养方法并进行初步的形态观察,为破骨细胞学及与其相关疾病的发病机制的研究提供更有意义的手段。方法:采用小鼠骨髓间充质干细胞通过1,25-(OH)2D诱导分化为破骨3细胞的培养方法,并观察原代成骨细胞对该方法破骨细胞形成及其功能的影响。根据是否加原代成骨细胞,分成未加成骨细胞、加成骨细胞二组,未加成骨细胞组是骨髓间充质干细胞直接诱导培养,加成骨细胞组是骨髓间充质干细胞与原代成骨细胞共同培养。分别培养6,9,12及15d,各组细胞到培养时间后取出进行TRAP染色阳性的多核细胞计数、骨片甲苯胺蓝染色及扫描电镜观察。结果:未加成骨细胞、加成骨细胞两组的骨髓间充质干细胞经培养后均出现破骨细胞,而且随着培养时间的延长,破骨细胞及骨片吸收陷窝的数目增多。培养相同时间的未加成骨细胞、加成骨细胞两组之间的破骨细胞及骨片吸收陷窝的数目差异无显著性意义。结论:通过1,25-(OH)2D诱导骨髓中的间充质干细胞培养破骨细胞的3方法是可行的,而且骨髓间充质干细胞诱导培养成破骨细胞时加入原代成骨细胞共同培养对破骨细胞的形成和骨吸收功能并无明显促进作用。     

Mechanism of Bone Turnover

Bone remodelling is a cellular mechanism behind the bone turnover. It renews the old bone piece by piece and thus ensures the correction of possible microdamage and enables the regulation of mineral homeostasis. The basic mechanism of bone remodelling is similar in all types of bone and includes the resorption of old bone and the formation of equal amount of new bone at the same place. Histomorphometric studies have revealed the cellular details of remodelling and have shown that it is composed by the temporally and spatially regulated action of different bone cells and their precursors. Recent in vitro studies with osteoclasts and osteoblasts have increased our knowledge of the molecular mechanisms of bone remodelling. Molecular characterization of bone matrix proteins have suggested new functions to many of them and thereby increased our possibilities of understanding the local regulation mechanisms of remodelling. Bone matrix has been shown to contain several biologically active compounds which have effects on bone forming and resorbing cells and their precursors. Details of the functional mechanism of osteoclasts are also in the process of being discovered. However, several questions concerning bone remodelling still remain open: the molecular explanation for selection of the remodelling site; the coupling of bone resorption to formation, and the interactions between different cell types during the remodelling cycle.     

The role of osteoclasts in bone tissue engineering

The success of scaffold‐based bone regeneration approaches strongly depends on the performance of the biomaterial utilized. Within the efforts of regenerative medicine towards a restitutio ad integrum (i.e. complete reconstruction of a diseased tissue), scaffolds should be completely degraded within an adequate period of time. The degradation of synthetic bone substitute materials involves both chemical dissolution (physicochemical degradation) and resorption (cellular degradation by osteoclasts). Responsible for bone resorption are osteoclasts, cells of haematopoietic origin. Osteoclasts play also a crucial role in bone remodelling, which is essential for the regeneration of bone defects. There is, however, surprisingly limited knowledge about the detailed effects of osteoclasts on biomaterials degradation behaviour. This review covers the relevant fundamental knowledge and progress made in the field of osteoclast activity related to biomaterials used for bone regeneration. In vitro studies with osteoclastic precursor cells on synthetic bone substitute materials show that there are specific parameters that inhibit or enhance resorption. Moreover, analyses of the bone–material interface reveal that biomaterials composition has a significant influence on their degradation in contact with osteoclasts. Crystallinity, grain size, surface bioactivity and density of the surface seem to have a less significant effect on osteoclastic activity. In addition, the topography of the scaffold surface can be tailored to affect the development and spreading of osteoclast cells. The present review also highlights possible areas on which future research is needed and which are relevant to enhance our understanding of the complex role of osteoclasts in bone tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd.     

补肾中药对破骨细胞骨吸收功能的影响

目的:探讨补肾中药对破骨细胞(osteoclast,OC)骨吸收功能的影响。方法:取新生(出生24h内)SD乳鼠四肢骨髓分离培养OC,实验组加入不同(高、中、低)剂量的补肾中药血清,对照组采用无中药血清,采用酶动力学法测定培养上清中抗酒石酸酸性磷酸酶(tartrate resistant acid phosphatase,TRACP)的活性;利用甲苯胺蓝对骨吸收陷窝染色并在图像分析仪下测定骨吸收陷窝的面积和数目。结果:补肾中药高、中剂量组均降低TRACP活性,减少骨片上骨吸收陷窝的面积及数目,与空白对照组比较差异有显著性意义(P<0.01),高、中剂量组间比较差异有显著性意义(P<0.05),以中剂量组作用为明显。结论:补肾中药可降低破骨细胞培养上清中的TR ACP活性,减少骨吸收陷窝面积及数目,达到抑制破骨细胞的骨吸收功能目的。     

TRANCE Is Necessary and Sufficient for Osteoblast-mediated Activation of Bone Resorption in Osteoclasts

TRANCE (tumor necrosis factor–related activation-induced cytokine) is a recently described member of the tumor necrosis factor superfamily that stimulates dendritic cell survival and has also been found to induce osteoclastic differentiation from hemopoietic precursors. However, its effects on mature osteoclasts have not been defined. It has long been recognized that stimulation of osteoclasts by agents such as parathyroid hormone (PTH) occurs through a hormonal interaction with osteoblastic cells, which are thereby induced to activate osteoclasts. To determine whether TRANCE accounts for this activity, we tested its effects on mature osteoclasts. TRANCE rapidly induced a dramatic change in osteoclast motility and spreading and inhibited apoptosis. In populations of osteoclasts that were unresponsive to PTH, TRANCE caused activation of bone resorption equivalent to that induced by PTH in the presence of osteoblastic cells. Moreover, osteoblast-mediated stimulation of bone resorption was abrogated by soluble TRANCE receptor and by the soluble decoy receptor osteoprotegerin (OPG), and stimulation of isolated osteoclasts by TRANCE was neutralized by OPG. Thus, TRANCE expression by osteoblasts appears to be both necessary and sufficient for hormone-mediated activation of mature osteoclasts, and TRANCE-R is likely to be a receptor for signal transduction for activation of the osteoclast and its survival.     

1,25-Dihydroxyvitamin D3 stimulates rat osteoblastic cells to release a soluble factor that increases osteoclastic bone resorption.

Although 1,25-dihydroxyvitamin D3 stimulates osteoclastic bone resorption in vivo and in organ culture, the mechanism by which it effects this stimulation is unknown. We have recently found that the agent does not stimulate resorption by osteoclasts mechanically disaggregated from bone and incubated on slices of cortical bone. This suggests that the osteoclasts were removed by disaggregation from the influence of some cell type, present in intact bone, that mediates hormone responsiveness. We therefore tested the ability of osteoblastic cells derived from neonatal rat calvariae and of cloned, hormone-responsive osteosarcoma cells (UMR106) to restore hormone responsiveness to unresponsive populations of osteoclasts. We found that osteoblastic cells from both sources induced a two- to fourfold stimulation of osteoclastic bone resorption in the presence of 1,25-dihydroxyvitamin D3. Stimulation was observed at concentrations of 10(-10) M and above. Actinomycin D and cycloheximide did not affect bone resorption by osteoclasts incubated alone, but abolished the capacity of osteoblastic cells to stimulate osteoclastic resorption in the presence of 1,25-dihydroxyvitamin D3. When calvarial cells or osteoblastlike UMR cells were incubated with the hormone, they produced a factor in cell-free supernatants that stimulated bone resorption by disaggregated osteoclasts. These experiments suggest that 1,25-dihydroxyvitamin D3 stimulates bone resorption through a primary action on osteoblastic cells, that are induced by the hormone to produce a factor that stimulates osteoclastic bone resorption.     

核因子κB受体活化因子配体诱导形成的成熟破骨细胞

背景：破骨细胞作为一种终末细胞,获取困难,而且没有成熟破骨细胞株等因素限制了其应用。先前国内外对破骨细胞的获取一般采用基质细胞诱导培养或共培养,或运用核因子κB受体活化因子配体和巨噬细胞集落刺激因子共同作用诱导形成成熟的破骨细胞。目的：观察小鼠单核巨噬细胞RAW264．7的一般生物学特征,分析其在核因子κB受体活化因子配体诱导下形成成熟破骨细胞的可行性。方法：培养RAW264．7后,用核因子κB受体活化因子配体诱导RAW264．7细胞7d后观察抗酒石酸酸性磷酸酶染色结果,以抗酒石酸酸性磷酸酶染色阳性,细胞核≥3个为破骨细胞。以鬼笔环肽荧光染色观察纤维性肌动蛋白环,甲苯胺蓝染色观察牛骨片表面的吸收陷窝隋况。结果与结论：核因子κB受体活化因子配体可诱导RAW264．7细胞形成抗酒石酸酸性磷酸酶染色阳性的多核细胞,形成纤维性肌动蛋白环,电镜下可见骨片上圆形或椭圆形的吸收陷窝。提示RAW264．7是一种较好的破骨前体细胞模型,可用于破骨细胞分化研究。单用核因子κB受体活化因子配体诱导RAW264．7细胞分化成熟,减少了巨噬细胞集落刺激因子的应用,使培养体系更加简单,易于操作,诱导出的细胞纯度高,适合于破骨细胞的生物学和生化研究。     

Regulation of sodium-dependent phosphate transport in osteoclasts.

Osteoclasts are the primary cells responsible for bone resorption. They are exposed to high ambient concentrations of inorganic phosphate (Pi) during the process of bone resorption and they possess specific Pi-transport system(s) capable of taking up Pi released by bone resorption. By immunochemical studies and PCR, we confirmed previous studies suggesting the presence of an Na-dependent Pi transporter related to the renal tubular "NaPi" proteins in the osteoclast. Using polyclonal antibodies to NaPi-2 (the rat variant), an approximately 95-kD protein was detected, localized in discrete vesicles in unpolarized osteoclasts cultured on glass coverslips. However, in polarized osteoclasts cultured on bone, immunofluorescence studies demonstrated the protein to be localized exclusively on the basolateral membrane, where it colocalizes with an Na-H exchanger but opposite to localization of the vacuolar H-ATPase. An inhibitor of phosphatidylinositol 3-kinase, wortmannin, and an inhibitor of actin cytoskeletal organization, cytochalasin D, blocked the bone-stimulated increase in Pi uptake. Phosphonoformic acid (PFA), an inhibitor of the renal NaPi-cotransporter, reduced NaPi uptake in the osteoclast. PFA also elicited a dose-dependent inhibition of bone resorption. PFA limited ATP production in osteoclasts attached to bone particles. Our results suggest that Pi transport in the osteoclast is a process critical to the resorption of bone through provision of necessary energy substrates.     

Osteoblasts mediate interleukin 1 stimulation of bone resorption by rat osteoclasts

A monocyte-derived factor with IL-1-like properties has recently been shown to cause resorption of bone in organ culture. We have investigated the action of IL-1 on disaggregated populations of osteoclasts, incubated alone or in the presence of osteoblastic cells, in an attempt to identify the target cell for IL-1 in bone, and to elucidate the mechanism by which IL-1 induces osteoclastic resorption. Osteoclasts were disaggregated from neonatal rat long bones and incubated on slices of human femoral cortical bone. Under these conditions, the majority of osteoclasts form distinctive excavations in the bone surface within 24 h, the volume of which can be quantified by computer-assisted morphometric and stereophotogrammetic techniques. IL-1 had no effect on bone resorption by osteoclasts alone, but when incubated in the presence of calvarial cells or cloned osteosarcoma cells, it induced a 3.8 (+/- 0.38)-fold increase in osteoclastic bone resorption, with significant enhancement at concentrations of greater than or equal to 30 pg/ml. The osteoblastic populations themselves did not resorb bone. The mechanism by which osteoblastic cells stimulate osteoclasts did not appear to depend upon PG synthesis; nor could we detect a diffusible substance in the medium of stimulated cocultures. These results indicate that IL-1 stimulates bone resorption through a primary action on osteoblasts, which are induced by IL-1 to transmit a short-range signal that stimulates osteoclastic bone resorption.     

DNA synthesis is not necessary for osteoclastic responses to parathyroid hormone in cultured fetal rat long bones.

Osteoclasts, the principal cells mediating bone resorption, are believed to increase their size, number, and resorbing activity in response to parathyroid hormone (PTH) through mechanisms dependent upon the fusion of specific mononuclear precursor cells into either new or existing multinucleated osteoclasts. To address the question of whether these actions of PTH are dependent on the replication of osteoclast precursor cells, we examined the ability of an inhibitor of DNA synthesis, hydroxyurea (HU), to alter bone resorption, osteoclast formation, and DNA synthesis in cultured fetal rat bones treated with PTH. We found that HU significantly reduced [3H]thymidine incorporation into the bones and labeling of osteoclast nuclei by greater than 90%, but did not prevent PTH from stimulating bone resorption, measured as the release of 45Ca, or from increasing the number of osteoclasts in the bones. In bones cultured without PTH, HU decreased the rate of bone resorption, but not the number of osteoclasts per bone. We conclude that in fetal rat bone cultures, PTH can increase osteoclast number and stimulate bone resorption by affecting existing osteoclasts and osteoclast precursors, and that replication of osteoclast precursor cells is not necessary for PTH to stimulate a resorptive response. In unstimulated cultures it appears that HU inhibits bone resorption by affecting mechanisms that are independent of changes in osteoclast number and that may be influenced by cell replication or other unknown factors.     

Oxygen-derived free radicals stimulate osteoclastic bone resorption in rodent bone in vitro and in vivo.

The mechanisms by which bone resorbing osteoclasts form and are activated by hormones are poorly understood. We show here that the generation of oxygen-derived free radicals in cultured bone is associated with the formation of new osteoclasts and enhanced bone resorption, identical to the effects seen when bones are treated with hormones such as parathyroid hormone (PTH) and interleukin 1 (IL-1). When free oxygen radicals were generated adjacent to bone surfaces in vivo, osteoclasts were also formed. PTH and IL-1-stimulated bone resorption was inhibited by both natural and recombinant superoxide dismutase, an enzyme that depletes tissues of superoxide anions. We used the marker nitroblue tetrazolium (NBT) to identify the cells that were responsible for free radical production in resorbing bones. NBT staining was detected only in osteoclasts in cultures of resorbing bones. NBT staining in osteoclasts was decreased in bones coincubated with calcitonin, an inhibitor of bone resorption. We also found that isolated avian osteoclasts stained positively for NBT. NBT staining in isolated osteoclasts was increased when the cells were incubated with bone particles, to which they attach. We confirmed the formation of superoxide anion in isolated avian osteoclasts using ferricytochrome c reduction as a method of detection. The reduction of ferricytochrome c in isolated osteoclasts was inhibited by superoxide dismutase. Our results suggest that oxygen-derived free radicals, and particularly the superoxide anion, are intermediaries in the formation and activation of osteoclasts.