双膦酸盐对破骨细胞分化及抗酒石酸酸性磷酸酶的影响

背景:抗酒石酸酸性磷酸酶是破骨细胞分化及骨吸收功能的特异性标志酶,是破骨细胞分化成熟的标志。目的:观察双膦酸盐对破骨细胞分化及骨吸收功能相关因子抗酒石酸酸性磷酸酶的影响。方法:小鼠单核巨噬细胞RAW264.7诱导培养破骨细胞。实验分2组:对照组开始时加入质量浓度100μg/L核因子kB受体活化因子配体进行诱导至收获细胞,双膦酸盐组在对照组的基础上加入10-7 mol/L阿仑膦酸盐处理至收获细胞。培养第7天检测各组破骨细胞生成和骨吸收功能,免疫荧光检测两组抗酒石酸酸性磷酸酶表达的差异,Western blot检测抗酒石酸酸性磷酸酶蛋白表达情况。结果与结论:各组细胞均有抗酒石酸酸性磷酸酶阳性多核破骨细胞生成,并在牙本质磨片上形成吸收陷窝;但对照组抗酒石酸酸性磷酸酶阳性多核细胞数目、吸收陷窝数目及陷窝面积均大于双膦酸盐组(P0.01)。免疫荧光检测显示,对照组抗酒石酸酸性磷酸酶表达均强于双膦酸盐组(P0.01)。Western blot检测显示,双膦酸盐组抗酒石酸酸性磷酸酶蛋白的表达低于对照组(P0.01)。说明双膦酸盐通过抑制抗酒石酸酸性磷酸酶蛋白的表达,阻碍破骨细胞分化生成及骨吸收功能。     

双膦酸盐对破骨细胞分化中组织蛋白酶K及骨吸收功能的影响

背景:有研究表明双膦酸盐可抑制破骨细胞的骨吸收功能,但对其骨吸收功能关键细胞因子组织蛋白酶K是否产生作用,至今少有报道。目的:观察双膦酸盐对破骨细胞分化中组织蛋白酶K及骨吸收功能影响。方法:用小鼠单核巨噬细胞RAW264.7诱导培养破骨细胞。实验分2组:对照组加入质量浓度100μg/L核因子κB受体活化因子配体进行诱导至收获细胞,双膦酸盐组在对照组的基础上加入10-7 mol/L阿仑膦酸盐处理至收获细胞。培养第7天检测各组破骨细胞生成和骨吸收功能,培养72 h免疫荧光检测两组组织蛋白酶K表达差异,Western blot检测组织蛋白酶K蛋白表达情况。结果与结论:两组均有抗酒石酸酸性磷酸酶阳性多核破骨细胞生成,并在牙本质磨片上形成吸收陷窝;但对照组抗酒石酸酸性磷酸酶阳性多核细胞数目、吸收陷窝数目及陷窝面积均大于双膦酸盐组(P0.01)。免疫荧光检测组织蛋白酶K表达对照组强于双膦酸盐组(P0.01);Western blot检测组织蛋白酶K表达双膦酸盐组低于对照组(P0.01)。结果证实,双膦酸盐通过抑制组织蛋白酶K因子的表达,阻碍破骨细胞的骨吸收功能。     

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7 d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情况。 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。     

人破骨细胞分化中重组结核杆菌热休克蛋白10的影响

背景:体外小鼠颅盖骨实验已证实了其结核杆菌热休克蛋白10的破骨效应。目的:在诱导破骨细胞分化的体外细胞培养系统中,研究重组结核杆菌热休克蛋白10对破骨细胞分化的影响及相关机制。方法:选用人巨噬细胞集落刺激因子依赖性附着性血液单个核细胞,实验分为:核因子κB受体活化因子配体+重组结核杆菌热休克蛋白10组、核因子κB受体活化因子配体组、重组结核杆菌热休克蛋白10组(1 mg/L)、阴性对照组(完全培养基),核因子κB受体活化因子配体+重组结核杆菌热休克蛋白10组、重组结核杆菌热休克蛋白10组中重组结核杆菌热休克蛋白10质量浓度为1 mg/L,在含有巨噬细胞集落刺激因子的a-MEM培养液重悬单核细胞,各组培养7,14,21 d后,观察所形成的抗酒石酸酸性磷酸酶阳性染色多核细胞的形态、数目、骨吸收面积;各组NFATc1、c-Fos基因及蛋白表达情况。结果与结论:阴性对照组无抗酒石酸酸性磷酸酶阳性多核破骨细胞分化生成,其余各组均有抗酒石酸酸性磷酸酶阳性多核破骨细胞分化生成,并在小牛骨磨片上形成吸收陷窝;重组结核杆菌热休克蛋白10组形成的破骨细胞分化细胞数目、吸收陷窝数目及陷窝面积显著低于核因子κB受体活化因子配体+重组结核杆菌热休克蛋白10组;阴性对照组NFATc1、c-Fos基因表达水平显著低于核因子κB受体活化因子配体+重组结核杆菌热休克蛋白10组和重组结核杆菌热休克蛋白10组,而重组结核杆菌热休克蛋白10组表达NFATc1、c-Fos蛋白,显著低于核因子κB受体活化因子配体+重组结核杆菌热休克蛋白10组。提示结核杆菌热休克蛋白10参与破骨细胞分化的形成,可能与诱导相关基因NFATc1、c-Fos表达上调有关。     

大鼠破骨细胞体外分离培养和鉴定

采用机械分离方法，从新生大骨长管骨分离破骨细胞获得成功。分离的破骨细胞具有如下特性：１．在体外迅速贴附于盖玻片或骨片；２．多核（一般为３￣１０个细胞核）；３．伪足运动活跃，降钙素或降钙素基因相关肽可以抑制其伪足运动；４．酸性磷酸酶染色强阳性，酸性醋酸酯酶弱阳性，ＰＡＳ中等阳性；５．细胞悬液与骨磨片共同培养，可以形成骨吸收陷窝。由此可见，本研究分离的细胞，符合破骨细胞的公认特性，故本法分离培养破骨细     

抗骨松丹杞颗粒含药血清对成骨-破骨细胞共培养体系中破骨细胞功能的影响

目的:观察补肾方抗骨松丹杞颗粒含药血清在成骨-破骨细胞共同培养体系中对大鼠破骨细胞(OC)骨吸收功能的影响。方法:取1 d龄SD大鼠的胎鼠颅骨与四肢骨分别分离、培养成骨细胞和破骨细胞,建立细胞上清相通但细胞间不相互混杂的平面式成骨-破骨细胞共育体系,实验分为不同浓度(低、中、高)的补肾方含药血清组和对照组进行比较,用重氮盐法检测抗酒石酸酸性磷酸酶(TRAP)和光镜观察骨陷窝数。结果:25%的补肾方含药血清组在48 h、72 h、96 h成骨-破骨细胞共育体系中OC分泌TRAP的活性明显降低于对照组;25%的补肾方含药血清组在48 h、72 h、120 h所形成骨吸收陷窝的数目明显低于对照组(P0.01)。结论:补肾方抗骨松丹杞颗粒含药血清在共育体系中能够抑制OC活性。     

CaMKIIδ在破骨细胞分化不同阶段表达规律的研究

目的:研究钙离子/钙调蛋白依赖性蛋白激酶II(Ca MKII)δ在破骨细胞分化不同阶段的表达规律,以揭示其在破骨细胞分化中的作用。方法:应用50μg/L核因子κB受体激活因子配体(RANKL)诱导小鼠RAW264.7细胞向破骨细胞分化;通过抗酒石酸酸性磷酸酶(TRAP)染色及骨磨片吸收陷窝检测评价破骨细胞生成情况;同时于诱导第0、1、3、5天末通过免疫荧光细胞化学、RT-q PCR和Western blot法检测Ca MKIIδ的mRNA及蛋白表达水平。结果:TRAP染色及骨吸收陷窝检测显示于诱导第5天有多核破骨细胞生成。第0、1、3、5天Ca MKIIδ的mRNA表达水平分别为1.028±0.041、2.478±0.087、10.524±1.284和42.914±2.667,蛋白相对水平分别为0.762、0.963、1.802和3.136,免疫荧光细胞化学检测显示Ca MKIIδ的荧光6强度呈时间依赖性递增。结论:Ca MKIIδ的表达随破骨细胞分化逐步增高,提示Ca MKIIδ在破骨细胞分化中可能起着关键调控作用。     

3种不同矫治器正畸作用下牙周骨组织重塑:压力侧破骨细胞分化因子的表达

背景:国内外研究表明破骨细胞分化因子在正畸牙移动骨改建骨重塑过程中与破骨细胞的分化和功能密切相关。目的:分析3种不同矫治器正畸治疗对大鼠牙周组织重塑过程中压力侧破骨细胞分化因子表达的影响,显示矫治器正畸过程与宿主组织重建的生物相容性。方法:选取80只健康Wistar大鼠,建立正畸牙移位的大鼠模型,随机数字表法分为4组。对照组、DamonⅢ矫治器组、Begg矫治器组、MBT矫治器组。于各组矫治器正畸后3,7,14,21 d各处死4只动物。通过破骨细胞抗酒石酸酸性磷酸酶染色法检测大鼠压力侧牙槽骨组织的破骨细胞数;通过RT-PCR法检测大鼠压力侧的牙周骨组织中破骨细胞分化因子基因的表达变化及时间分布特点。结果与结论:与对照组相比,不同矫治器组压力侧的牙槽骨组织中的抗酒石酸酸性磷酸酶染色阳性破骨细胞计数和破骨细胞分化因子基因的表达水平随正畸时间的增加而升高,第7天时最高,而后逐渐降低。第7天时DamonⅢ矫治器组抗酒石酸酸性磷酸酶染色阳性破骨细胞计数和破骨细胞分化因子基因表达水平高于MBT矫治器组、Begg矫治器组及对照组(P0.05)。结果表明在大鼠骨改建过程中破骨细胞分化因子基因表达的变化与破骨细胞抗酒石酸酸性磷酸酶染色阳性破骨细胞数的变化规律一致,第7天时,DamonⅢ矫治器组破骨细胞分化因子mR NA表达及破骨细胞数高于其他组。     

破骨细胞分化过程中丙酮酸的作用

背景：糖酵解在破骨细胞分化过程中起关键作用,成熟破骨细胞骨吸收主要依赖于糖酵解。丙酮酸作为糖酵解的终末产物,在三大营养物质的代谢中起重要的枢纽作用。目的：探讨丙酮酸对破骨细胞分化的影响。方法：采用CCK-8法检测不同浓度(0.1,1,10,20,30,50 mmol/L)丙酮酸对RAW264.7细胞活性的影响,筛选出安全浓度丙酮酸。将RAW264.7细胞分组干预：空白对照组加入完全培养基(含体积分数10%胎牛血清、1%双抗的α-MEM培养基),对照组加入含核因子κB受体活化因子配体的完全培养基,实验组加入核因子κB受体活化因子配体与不同浓度丙酮酸的完全培养基,分别进行抗酒石酸酸性磷酸酶染色、细胞骨架纤维性肌动蛋白染色、RT-qPCR检测、Western blot检测与骨吸收陷窝实验。结果与结论：(1)CCK-8检测显示,丙酮酸对RAW264.7细胞的最大半数抑制浓度为8.923 mmol/L,后续实验选择0.1,1,5 mmol/L为安全浓度;(2)抗酒石酸酸性磷酸酶染色显示,1 mmol/L丙酮酸促进RAW264.7细胞向破骨细胞分化;(3)细胞骨架纤维性肌动蛋白染色显示,1mmol...     

密骨打老儿丸含药血清对共育体系中成骨细胞和破骨细胞功能的影响

 目的： 观察密骨打老儿丸（Migu-Dalaoer pill,MDP）含药血清在成骨-破骨细胞共同培养体系中对成骨细胞（osteoblasts,OB）增殖和破骨细胞（osteoclasts,OC）骨吸收功能的影响。方法： 利用分段酶消化法从胎鼠颅骨中分离出OB,取1日龄SD大鼠四肢股骨和胫骨分离培养OC,建立培养上清相通但2种细胞间互不接触的成骨-破骨细胞共育模型。实验分为不同浓度（低、中、高）的MDP含药血清组和对照组进行比较,以细胞增殖（MTT 法）和碱性磷酸酶（alkaline phosphatase,ALP）活性代表OB的成骨活性,以抗酒石酸酸性磷酸酶（tartrate-resistant acid phosphatase,TRAP）活性和骨吸收陷窝数目代表OC的破骨能力进行测定。结果： 与对照组相比,中、高浓度MDP含药血清在成骨-破骨细胞共同培养体系中6和7 d 能显著提高OB数目和 ALP 活性（P<0.01）。与对照组相比,中、高浓度MDP含药血清在成骨-破骨细胞共同培养体系中6和7 d 能显著降低OC骨吸收陷窝的数目和分泌 TRAP 的活性（P<0.01）。结论： 密骨打老儿丸含药血清在共育体系中能够促进OB增殖和骨形成,同时抑制OC骨吸收功能。     

Ischemic stroke in rats enhances bone resorption in vitro

We hypothesized that the formation and differentialtion of osteoclasts are accelerated and the potential of bone resorption is increased in the hemiplegic bone marrow in the early stage of stroke. We randomly divided white female Sprague-Dawley (SD) rats (n = 30) into two groups, stroke (n = 15) and sham group (n = 15). On the 7th day after stroke, after cutting away the epiphyses of the femurs and tibias, diaphyseal channels were flushed using α-minimum essential medium (α-MEM) and bone marrow cells were collected. Bone marrow stem cells, which were extracted from the femur and tibia, were cultured on the 7th day after middle cerebral artery occlusion. We then estimated the ratio of non-adherent cells to total bone marrow cells that included osteoclast precursor cells. After culturing these cells separately, cells that tested positive on the tartrate resistant acid phosphatase (TRAP) were counted and bone resorption was evaluated by using the OAAS™ plate. In comparison to the control group, the stroke group showed a higher increase of non-adherent cells in the hemiplegic side bone marrow. In addition, after the primary culture, the stroke group showed an increased number of TRAP positive cells and a higher degree of bone resorption estimated by OAAS™ plate. As a result, osteoclastogenesis and osteoclast differentiation are accelerated and the potential of bone resorption is increased in the hemiplegic bone marrow and these changes are detected as early as within the first week after middle cerebral artery occlusion in SD rats.     

CD14- mononuclear stromal cells support (CD14+) monocyte-osteoclast differentiation in aneurysmal bone cyst

Aneurysmal bone cyst (ABC) is a benign osteolytic bone lesion in which there are blood-filled spaces separated by fibrous septa containing giant cells. The nature of the giant cells in this lesion and the mechanism of bone destruction in ABC is not certain. In this study, we have analysed several characteristics of mononuclear and multinucleated cells in the ABC and examined the cellular and molecular mechanisms of ABC osteolysis. The antigenic and functional phenotype of giant cells in ABC was determined by histochemistry/immunohistochemistry using antibodies to macrophage and osteoclast markers. Giant cells and CD14+ and CD14- mononuclear cells were isolated from ABC specimens and cultured on dentine slices and coverslips with receptor activator of nuclear factor κB ligand (RANKL)+/- macrophage-colony stimulating factor (M-CSF) and functional and cytochemical evidence of osteoclast differentiation sought. Giant cells in ABC expressed an osteoclast-like phenotype (CD51+, CD14-, cathepsin K+, TRAP+) and were capable of lacunar resorption, which was inhibited by zoledronate, calcitonin and osteoprotegerin (OPG). When cultured with RANKL±M-CSF, CD14+, but not CD14-, mononuclear cells differentiated into TRAP+ multinucleated cells that were capable of lacunar resorption. M-CSF was not necessary for osteoclast formation from CD14+ cell cultures. CD14- cells variably expressed RANKL, OPG and M-CSF but supported osteoclast differentiation. Our findings show that the giant cells in ABC express an osteoclast-like phenotype and are formed from CD14+ macrophage precursors. CD14- mononuclear stromal cells express osteoclastogenic factors and most likely interact with CD14+ cells to form osteoclast-like giant cells by a RANKL-dependent mechanism.     

Identification of cell types responsible for bone resorption in rheumatoid arthritis and juvenile rheumatoid arthritis.

Focal resorption of bone at the bone-pannus interface is common in rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) and can result in significant morbidity. However, the specific cellular and hormonal mechanisms involved in this process are not well established. We examined tissue sections from areas of bone erosion in patients with RA and JRA. Multinucleated cells (MNCs) were present in resorption lacunae in areas of calcified cartilage and in subchondral bone immediately adjacent to calcified cartilage, as previously described. mRNA for the calcitonin receptor (CTR) was localized to these MNCs in bone resorption lacunae, a finding that definitively identifies these cells as osteoclasts. These MNCs were also positive for tartrate-resistant acid phosphatase (TRAP) mRNA and TRAP enzymatic activity. Occasional mononuclear cells on the bone surface were also CTR positive. Mononuclear cells and MNCs not on bone surfaces were CTR negative. The restriction of CTR-positive cells to the surface of mineralized tissues suggests that bone and/or calcified cartilage provide signals that are critical for the differentiation of hematopoietic osteoclast precursors to fully differentiated osteoclasts. Some MNCs and mononuclear cells off bone and within invading tissues were TRAP positive. These cells likely represent the precursors of the CTR-TRAP-positive cells on bone. Parathyroid hormone receptor mRNA was present in cells with the phenotypic appearance of osteoblasts, in close proximity to MNCs, and in occasional cells within pannus tissue, but not in the MNCs in bone resorption lacunae. These findings demonstrate that osteoclasts within the rheumatoid lesion do not express parathyroid hormone receptor. In conclusion, the resorbing cells in RA exhibit a definitive osteoclastic phenotype, suggesting that pharmacological agents that inhibit osteoclast recruitment or activity are rational targets for blocking focal bone erosion in patients with RA and JRA.     

Giant cells in pigmented villo nodular synovitis express an osteoclast phenotype.

AIM: To determine the cytochemical and functional phenotype of multinucleated giant cells in pigmented villo nodular synovitis (PVNS). METHODS: Giant cells isolated from a patient with PVNS of the knee were assessed for a number of markers used to distinguish osteoclasts from macrophages/ macrophage polykaryons: evidence of tartrate resistant acid phosphatase (TRAP) activity; expression of CD11b, CD14, CD51, and calcitonin receptors; and the ability of the giant cells to carry out lacunar resorption. RESULTS: Isolated giant cells expressed an osteoclast antigenic phenotype (positive for CD51, negative for CD11b and CD14) and were TRAP and calcitonin receptor positive. They also showed functional evidence of osteoclast differentiation, producing numerous lacunar bone resorption pits on bone slices in short term culture. CONCLUSIONS: The giant cells in this case of PVNS express all the phenotypical features of osteoclasts including the ability to carry out lacunar resorption. This may account for the bone destruction associated with this aggressive synovial lesion.     

Multinucleated cells formed on calcified dentine from mouse bone marrow cells treated with 1 alpha,25-dihydroxyvitamin D3 have ruffled borders and resorb dentine

Osteoclast-like multinucleated cells were formed from mouse bone marrow mononuclear cells, and their morphology on coverslips and on calcified dentine slices was compared by means of transmission electron microscopy. Addition of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] to bone marrow cells cultured on coverslips greatly stimulated the formation of multinucleated cells within 8 days. These multinucleated cells had the cytological features of osteoclasts (abundant pleomorphic mitochondria, a large number of vacuoles and lysosomes, many stacks of Golgi membranes, and an extensive canalicular system), but they developed neither ruffled borders nor clear zones. The multinucleated cells appeared to result from direct fusion of mononuclear progenitor cells, whose structural features were similar to those of multinucleated cells. Like isolated osteoclasts, both multinucleated cells and their precursors exhibited an intense reaction for tartrate-resistant acid phosphatase (TRACP) in the cisterns of endoplasmic reticulum and lysosomes. Multinucleated cells formed from alveolar macrophages in the presence of 1 alpha,25(OH)2D3 were totally negative for TRACP reaction. When marrow cells were cultured on dentine slices in the presence of 1 alpha,25(OH)2D3, some of the multinucleated cells were located in the shallow resorption lacunae of dentine surfaces, and they developed the characteristic ruffled borders and clear zones. The narrow extracellular spaces of the ruffled borders, the adjacent pale endocytotic vacuoles, and the dark lysosomes located in the perinuclear cytoplasm of the multinucleated cells contained numerous apatite crystals delete in resorption lacunae. These results indicate that 1) the multinucleated cells formed on coverslips from mouse marrow cells treated with 1 alpha,25(OH)2D3 exhibit non-functional basic features of osteoclast morphology, and 2) differentiation of the multinucleated cells into functional osteoclasts requires some components of calcified dentine.     

Inhibitory effect of CGRP on osteoclast formation by mouse bone marrow cells treated with isoproterenol

The present study was designed to elucidate the mode of action of isoproterenol (Isp; adrenergic beta-agonist) and to characterize the effect of the calcitonin gene-related peptide (CGRP; sensory neuropeptide) on osteoclast formation induced by Isp in a mouse bone marrow culture system. Treatment of mouse bone marrow cells with Isp generated tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells (MNCs) capable of excavating resorptive pits on dentine slices, and caused an increase in receptor activator of NF-kappaB ligand (RANKL) and a decrease in osteoprotegerin (OPG) production by the marrow cells. The osteoclast formation was significantly inhibited by OPG, suggesting the involvement of the RANKL-RANK system. CGRP inhibited the osteoclast formation caused by Isp or soluble RANKL (s-RANKL) but had no influence on RANKL or OPG production by the bone marrow cells treated with Isp, suggesting that CGRP inhibited the osteoclast formation by interfering with the action of RANKL produced by the Isp-treated bone marrow cells without affecting RANKL or OPG production. This in vitro data suggest the physiological interaction of sympathetic and sensory nerves in osteoclastogenesis in vivo.     

Inhibition of leukotriene function can modulate particulate-induced changes in bone cell differentiation and activity.

Aseptic loosening remains the major problem facing arthroplasty longevity with particulates from component materials touted as the cause of periprosthetic osteolysis. Proposed mechanisms in aseptic bone loss include: increased resorption, increased differentiation of osteoclasts (and/or macrophages locally), and decreased osteoblastic bone formation. Leukotrienes participate in osteoclastic bone resorption. We investigated inhibiting leukotrienes synthesis, using ICI 230487, to ameliorate the effects of particulates on osteoclast pit formation and also assessed the effects of alendronate, a bisphosphonate, on pit formation. Three particulates were used: ultra high molecular weight polyethylene (UHMWPE), polymethylmethacrylate (PMMA) and hydroxyapatite (HA). Osteoclast resorption was increased with UHMWPE, PMMA, and HA particles. Interventions with alendronate and ICI 230487 reduced particulate-induced osteoclast resorption. Both ICI 230487 and alendronate reduced osteoclast numbers at higher doses. To assess the effect of particulates on osteoclast and macrophage differentiation, mouse bone marrow was cultured and stained for tartrate resistant acid phosphatase colonies (TRAP+, osteoclasts) and nonspecific esterase positive colonies (NSE+, macrophage precursors). Particulates increased both TRAP+ and NSE+ colony formation. These increases were inhibited by ICI 230487. Particulates also inhibited osteoblast function assessed by the development of mineralized nodules and alkaline phosphatase positive (AP+) colony area. ICI 230487 partly protected osteoblast function from this particulate effect. Blockade of leukotriene production may prove a useful therapeutic intervention for particulate-induced aseptic loosening by inhibiting resorptive activity, reducing the pro-inflammatory cell populations induced and recruited by these particulates, as well as ameliorating the negative effects of inflammatory mediators on osteoblast function.Copyright 2001 John Wiley & Sons, Inc.     

Modulation of ovariectomy-related bone loss by parathyroid hormone in rats

Studies were carried out to examine whether parathyroid hormone (PTH) will prevent the age-related bone loss that results from ovarian hormone deficiency and to explore the mechanism of its action. Ovariectomy caused a significant decrease in bone density in the distal metaphysis and mid-diaphysis, but not in the vertebra and proximal metaphysis. The decrease was prevented by PTH injection and in all the bones examined PTH administration increased bone density and bone calcium content above the levels in sham-operated controls. Similar findings were made in bone hydroxyproline levels. PTH treated ovariectomized animals had lower serum 25(OH)vitamin D and higher 1,25(OH)2 vitamin D levels than ovariectomized and sham operated animals that received solvent vehicle. Compared to the sham operated controls, ovariectomy caused a 4.5-fold increase in the number of tartrate resistant acid phosphatase (TRAP) positive multinuclear cells. This increase did not occur in PTH-treated animals. We conclude that PTH is effective in preventing ovarian hormone deficiency bone loss in rats. PTH may mediate this effect partly by stimulating osteoblastic bone formation and partly by increasing 1,25(OH)2 vitamin D-mediated calcium absorption. The data from TRAP positive multinuclear cells indicate that an etiologic component of ovarian hormone deficiency bone loss is the expansion of a pool of osteoclast progenitors and that the bone anabolic action of PTH involves, in part, a decrease in bone resorption as a result of the suppression of the proliferation of osteoclast progenitors.     

Human tumour-associated macrophages differentiate into osteoclastic bone-resorbing cells

Macrophages are commonly found within osteolytic secondary carcinomas in bone, but the manner in which these cells contribute to malignant bone resorption is uncertain. Macrophages isolated from primary breast carcinomas were co-cultured for up to 21 days with UMR 106 rat osteoblast-like cells on bone slices and glass coverslips in the presence and absence of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] and human macrophage colony stimulating factor (M-CSF). Cell cultures were then assessed for the presence of phenotypic markers of macrophage and osteoclast differentiation. Isolated cells were negative for osteoclast markers including tartrate-resistant acid phosphatase (TRAP), vitronectin receptor (VNR), and the ability to carry our lacunar bone resorption, but were positive for CD11b and CD14, macrophage markers which are not present on osteoclasts. In 21-day co-cultures of breast carcinoma tumour-associated macrophages (TAMs) and UMR 106 cells, incubated in the presence of 1,25(OH)₂D₃ and M-CSF, numerous TRAP- and VNR-positive multinucleated cells capable of extensive lacunar resorption were formed. Contact with UMR 106 cells and the presence of 1,25(OH)₂D₃ and M-CSF were absolute requirements for differentiation of human breast carcinoma TAMs into mature functional osteoclasts. TAM–osteoclast differentiation may represent an important cellular mechanism of osteolysis in metastatic skeletal carcinomas. © 1998 John Wiley & Sons, Ltd.     

Multinucleated cells formed on calcified dentine from mouse bone marrow cells treated with 1α,25-dihydroxyvitamin D3 have ruffled borders and resorb dentine

Osteoclast-like multinucleated cells were formed from mouse bone marrow mononuclear cells, and their morphology on coverslips and on calcified dentine slices was compared by means of transmission electron microscopy. Addition of 1α,25-dihydroxyvitamin D₃ [1α,25(OH)₂D₃] to bone marrow cells cultured on coverslips greatly stimulated the formation of multinucleated cells within 8 days. These multinucleated cells had the cytological features of osteoclasts (abundant pleomorphic mitochondria, a large number of vacuoles and lysosomes, many stacks of Golgi membranes, and an extensive canalicular system), but they developed neither ruffled borders nor clear zones. The multinucleated cells appeared to result from direct fusion of mononuclear progenitor cells, whose structural features were similar to those of multinucleated cells. Like isolated osteoclasts, both multinucleated cells and their precursors exhibited an intense reaction for tartrate-resistant acid phosphatase (TRACP) in the cisterns of endoplasmic reticulum and lysosomes. Multinucleated cells formed from alveolar macrophages in the presence of 1α,25(OH)₂D₃ were totally negative for TRACP reaction. When marrow cells were cultured on dentine slices in the presence of 1α,25(OH)₂D₃, some of the multinucleated cells were located in the shallow resorption lacunae of dentine surfaces, and they developed the characteristic ruffled borders and clear zones. The narrow extracellular spaces of the ruffled borders, the adjacent pale endocytotic vacuoles, and the dark lysosomes located in the perinuclear cytoplasm of the multinucleated cells contained numerous apatite crystals delete in resorption lacunae. These results indicate that (1) the multinucleated cells formed on coverslips from mouse marrow cells treated with 1α,25(OH)₂D₃ exhibit non-functional basic features of osteoclast morphology, and (2) differentiation of the multinucleated cells into functional osteoclasts requires some components of calcified dentine.