福莫特罗和ICI118551对大鼠成熟破骨细胞骨吸收功能的影响

目的研究选择性β2肾上腺素能激动剂福莫特罗(Formoterol)和阻滞剂ICI118551对体外培养大鼠成熟破骨细胞(osteoclast,OC)功能的影响,探讨β2肾上腺素能受体信号对骨代谢的影响。方法取清洁级出生24h内的SD乳大鼠,长骨干骨髓腔内壁机械分离成熟OC后分别加入不同浓度(10-5mol/L～10-9mol/L)的Formoterol和ICI118551,以抗酒石酸酸性磷酸酶(TRAP)染色观察破骨细胞形态,甲苯胺蓝染色计数骨片上的骨吸收陷窝数目,Image-ProPlus6.0图像软件分析骨片上骨吸收陷窝面积。结果破骨细胞与骨片共培养6天,不同浓度的Formoterol与对照组相比均可增加骨片上OC的骨吸收陷窝数目和面积;随着ICI118551浓度的提高骨片上骨吸收陷窝的数目和面积逐渐减少。结论β2肾上腺素能受体激动剂可促进体外培养OC的骨吸收功能,阻滞剂对OC的骨吸收功能有抑制作用,且呈剂量依赖性。     

重组人骨保护素对体外培养兔破骨细胞的影响

目的观察重组人骨保护素(recombinanthumanosteoprotegerin,rhOPG)对体外培养兔破骨细胞(osteoclast,OC)生存和功能的影响。方法将rhOPG用于干预从新生兔分离出的OC,于干预后1、3、7d取细胞玻片、皮质骨片进行HE、Giemsa、甲苯胺蓝染色,并观察抗酒石酸酸性磷酸酶(TRAP)染色阳性细胞和骨片吸收陷窝,扫描电镜进一步观察吸收陷窝形态。结果分离培养的兔OC多核形态明显;rhOPG对TRAP阳性OC生存的影响,1、3d结果差别不明显,7d的结果差异有显著性(P<0.05);rhOPG能够明显地抑制OC在骨片上形成吸收陷窝,三个时点计数结果差异均有显著性(P<0.01)。结论rhOPG可明显地抑制体外培养兔OC的骨吸收功能。     

阿司匹林对大鼠破骨细胞分化成熟和骨吸收活性的影响

目的 研究不同浓度阿司匹林对体外培养大鼠破骨细胞(Osteoclast,OC)分化成熟及骨吸收活性的影响.方法 建立由核激活因子受体配体(receptor activator of NF-κB ligand,RANKL)和巨噬细胞集落刺激因子(Macrophage colony stimulating factor,M-CSF)共同作用的大鼠破骨细胞骨髓诱导体系,将雌激素(10-6 mmol/L)和不同浓度的阿司匹林(0.25 mmol/L、0.5 mmol/L、1.0 mmol/L、1.5 mmol/L)分别作用于破骨细胞.诱导培养后分别对破骨细胞进行抗酒石酸酸性磷酸酶(The tartrate-resistant acid phosphatase,TRAP)染色,观察细胞形态,并计数破骨样细胞数量;将各组破骨细胞接种于骨磨片上,建立破骨细胞-骨磨片活性分析模型,于不同时间点对骨磨片进行光镜和扫描电镜观察,分析计算骨吸收陷窝面积.结果 与正常对照组相比,雌激素组破骨细胞数量和骨吸收陷窝面积低于正常对照组,差异有统计学意义(P＜0.05);且随着阿司匹林浓度的增加,阿司匹林组TRAP阳性多核破骨细胞数量、骨吸收陷窝面积逐渐减少直至消失,差异有统计学意义(P＜0.05).与雌激素组相比,低浓度阿司匹林组(0.25mmol/L)没有明显差异;但中、高浓度阿司匹林实验组(0.5mmol/L、1.0mmol/L、1.5mmol/L)破骨细胞数量和骨吸收陷窝面积减少,差异有统计学意义(P＜0.05).结论 阿司匹林对破骨细胞的分化成熟及骨吸收功能有抑制作用,且呈剂量依赖性,从而具有抗骨质疏松的作用.     

波尔定对破骨细胞分化及骨吸收功能的影响

目的研究波尔定对NF-κB受体活化因子配体(RANKL)诱导的小鼠单核细胞(RAW264.7)向破骨细胞(OC)分化及骨吸收功能的影响。方法采用RANKL(50 ng/ml)诱导RAW264.7细胞向OC分化,不同浓度波尔定(1、10、20、40、80μmol/L)联合分化培养。培养第4d采用抗酒石酸酸性磷酸酶(TRAP)染色,计算OC样细胞数量;比色法测定TRAP活性;Real-time PCR法检测各组OC标志性基因核因子κB受体活化因子(RANK)、活化T细胞核因子1(NFATc1)和c-fos基因的表达;CCK-8法检测波尔定对OC的毒性。培养至第9d,采用甲苯胺蓝染色并用Leica Qwin图像分析系统计算骨吸收陷窝面积。结果与对照组比较,TRAP阳性OC数量、TRAP活性、OC标志性基因RANK、NFATc1和c-fos的表达量及骨陷窝面积,随着波尔定浓度增加而减少,与对照组比较,20μmol/L、40μmol/L、80μmol/L波尔定可明显减少OC数量和TRAP活性(P0.05,P0.01),下调OC标志性基因RANK、NFATc1和c-fos的表达量及骨陷窝面积(P0.05),但以上浓度波尔定对OC均未产生毒性。结论波尔定对RANKL诱导的RAW264.7细胞向OC的分化及骨吸收功能具有抑制作用。     

淫羊藿苷对破骨细胞活性的影响

目的:观察淫羊藿苷对破骨细胞骨吸收及凋亡的影响,探讨淫羊藿苷的抗骨质疏松作用机制。方法:体外分离、培养兔破骨细胞,与玻片及骨磨片共同培养,用10-7、10-6、5×10-6、10-5mol/L浓度的淫羊藿苷刺激破骨细胞,倒置相差显微镜下观察活体细胞、HE染色、TRAP染色及骨吸收陷窝甲苯胺蓝染色,鉴定破骨细胞,并进行骨吸收陷窝计数和面积测量,吖啶橙染色观察凋亡破骨细胞所占的比例。结果:与空白对照组比较,10-6、5×10-6、10-5mol/L浓度的淫羊藿苷组破骨细胞凋亡率均明显增高,骨吸收陷窝数目、面积明显减少,随浓度增加抑制作用增强,差异有显著性意义(P<0.05)。结论:淫羊藿苷可诱导破骨细胞凋亡,抑制骨吸收,并随浓度增加抑制作用增强。     

血小板衍生生长因子－BB对破骨细胞功能影响的实验研究

目的探讨血小板衍生生长因子 -BB(platelet-derivedgrowthfactor-BB,PDGF -BB)对破骨细胞生物学功能的影响。方法 (1)利用酶消化法分离培养成人破骨细胞 ;(2)应用透射电子显微镜方法观察破骨细胞对PDGF -β 受体的表达 ;(3)在经过纯化的破骨细胞上清液中施加重组人基因PDGF -BB ,利用酶动力学方法测定培养上清液中的酸性磷酸酶 (ACP)和抗酒石酸酸性磷酸酶(TRAP)的活性 ;(4)通过Leica图像分析仪观察在PDGF -BB作用下 ,破骨细胞所形成骨吸收陷窝的数目与面积。结果 (1)破骨细胞膜上有胶体金颗粒沉着 ;(2)破骨细胞培养上清液中的ACP和TRAP活性随着PDGF -BB浓度的升高而增加 ,分别从(1.85±0.13)u/L和(1.73±0.15)u/L(对照组 )增加至(2.86±0.15)u/L和(2.75±0.24)u/L(40μg/L组 ,P<0.01) ;(3)在PDGF -BB的作用下 ,破骨细胞所形成的骨吸收陷窝的面积从(435.08±237.50)μm2(对照组 )增高至(630.26±240.64)μm2 (40μg/L组 ,P<0.01) ,每个骨片上骨吸收陷窝的数目亦从14.00±1.41增加为26.00±2.00(P<0.05或P<0.01)。结论PDGF -BB通过与PDGF -β受体结合 ,可直接促进破骨细胞的骨吸收功能     

用含药血清方法观察补肾益精方对破骨细胞功能的影响

目的探讨补肾益精方含药血清的制备条件及其对体外培养破骨细胞骨吸收功能的影响。方法取体重270±20g的SD大鼠,雌雄各半,每组10只,同等条件下制备补肾益精方含药血清和对照血清,分别观察不同采血时间、不同喂药时间、不同灌胃剂量和血清添加量对骨吸收陷窝数量的影响。结果末次灌胃后1h采血组的骨吸收陷窝数明显少于其他各组(P<0.05);灌胃1d和3d、7d组比较其含药血清的药效无差异,而与对照血清差异显著;随着灌胃剂量和含药血清添加量的提高,其骨吸收陷窝数明显减少。结论补肾益精方含药血清对破骨细胞骨吸收功能具有明显的抑制作用;补肾益精方用于破骨细胞药效观察的大鼠含药血清制备条件为等效剂量连续两次(间隔2h)灌胃,末次灌胃后1h采血,其血清添加浓度为30%。     

骨水泥颗粒促进肿瘤坏死因子α诱导的破骨细胞形成及其骨吸收作用

目的:验证骨水泥颗粒对肿瘤坏死因子α(TNFα)诱导的破骨细胞形成及其生物学活性的影响。方法:体外培养外周血单核细胞,对照组加入TNFα和白细胞介素-1α(IL-1α)及巨噬细胞克隆集落刺激因子(M-CSF),实验组并分别加入含有或不含有硫酸钙的骨水泥(PMMA±BaSO4)颗粒。对培养终末细胞作组织化学染色检测破骨细胞标志物抗酒石酸酸性磷酸酶(TRAP)的表达,并以象牙磨片上虫蚀样骨吸收陷窝的形成为指标检测破骨细胞的生物学活性;并比较各实验组中TRAP阳性多核细胞(multinucleatedcells,MNCs)及虫蚀样骨吸收陷窝形成时间的早晚。结果:各组TRAP阳性MNCs的数量无明显差异;PMMA±BaSO4组象牙磨片上骨吸收陷窝的面积均较对照组大,差异具有显著性(P<0.01);并且PMMA±BaSO4组TRAP阳性的MNCs及虫蚀样骨吸收陷窝的形成均较对照组早。结论:PMMA±BaSO4颗粒能够促进TNFα诱导的破骨细胞分化提早发生并促进其骨吸收活性。     

不同剂量激素对股骨近端的影响

目的 观察不同剂量地塞米松对大鼠股骨近端组织学、骨形态发生蛋白-2(BMP-2)及其受体表达、细胞凋亡的影响.方法 将96只雄性Wister大鼠随机分为对照组(C组)、地塞米松剂量5 mg/kg组(L组)、10 ms/ks组(M组)、15 ms/kg组(H组).各组分别于用药后2、4、6、8周对股骨近端1/3骨质进行组织学、BMP-2及其受体表达和细胞凋亡检测.结果 实验组骨小梁/髓腔面积比、皮质/髓腔面积比、骨形态发生蛋白Ⅰ型受体(BMP-R T)的含量均随用药时间的增加以及剂量的增加而降低,均低于C组.空骨陷窝计数和凋亡细胞计数则有随用药剂量及时间的增加而增加的趋势.L组的BMP-2平均染色面积百分比和BMP-2染色的平均吸光度在2周时明显高于对照组,而后降低,至8周时已明显低于对照组;M组和H组2周时接近正常水平,4、6、8周逐渐降低至较低水平.结论 大剂量地塞米松可以显著降低股骨近端的骨质质量;激素对股骨近端的影响具有剂量依赖性.     

17β-雌二醇对体外培养破骨细胞凋亡及其骨吸收调节作用

目的 观察17β-雌二醇对体外培养破骨细胞凋亡率的影响及其与骨吸收功能的关系。方法 在培养液中加入17β-雌二醇，透射电镜（transmission electron microscopy，TEM）观察破骨细胞内超微结构的改变，流式细胞仪（flow cytometry，FCM）观察不同浓度的17β-雌二醇在不同时间段对破骨细胞凋亡率的影响，同时用扫描电镜（scanning electron microscopy，SEM）观察破骨细胞在骨片上形成骨吸收陷窝数目及面积的变化。结果 17β-雌二醇可增加破骨细胞的凋亡率，这种作用具有剂量、时间依赖效应，同时，破骨细胞在骨片上形成的骨吸收陷窝的数目和面积减少。结论 17β-雌二醇可促进破骨细胞凋亡，从而抑制破骨细胞的骨吸收功能。     

Human breast cancer induces osteoclast activation and increases the number of osteoclasts at sites of tumor osteolysis

The cellular mechanism through which osseous breast cancer metastases induce the focal destruction of bone (tumor osteolysis) is unknown. An athymic mouse model designed for the study of tumor osteolysis was developed and the influence of two human breast cancer tumors on bone was studied. Tumor-induced osteolysis occurred between 7 and 10 weeks after inoculation of mouse femora with MDA-MB-231 or MDA-MB-435s breast cancer cells. An increase in osteoclast number and an increase in osteoclast size (area) were detected when tumor-bearing and sham-injected limbs were compared. In vitro analysis of the influence of the tumor-conditioned medium on osteoclast-mediated bone resorption revealed that this conditioned medium stimulated the resorption by increasing both the number of osteoclasts bound to bone and the number of bone resorption pits formed per osteoclast. In addition, in vitro analysis of the influence of breast cancer tumor cells on osteoclast formation or survival, or both, demonstrated that breast cancer cells induced a dramatic increase in the number of osteoclasts detected in culture. Taken in total, these findings suggest that human breast cancer tumors induce osteolysis by enhancing osteoclast adherence to bone, stimulating osteoclast-mediated bone resorption, and either prolonging the survival of osteoclasts or increasing osteoclast formation.     

重组人骨保护素对聚乙烯颗粒刺激破骨细胞功能的影响

目的通过观察重组人骨保护素（recombinant humanoste oprotegerin，rhOPG）对聚乙烯颗粒刺激破骨细胞功能的影响，探讨rhOPG防治人工关节无菌性松动的可行性。方法取出生24h内新西兰白兔5只，体重80～100g，雌雄不限。分离培养四肢长骨破骨细胞，以1&#215;10^5／mL密度均匀接种于大小为10mm&#215;10mm玻片和8mm&#215;8mm&#215;50μm骨片的24孔板内。根据加入rhOPG及聚乙烯颗粒浓度和密度的不同，玻片培养板和骨片培养板再分别分为1&#215;10^9／mL聚乙烯颗粒培养组（聚乙烯组）、1&#215;10^9／mL聚乙烯颗粒和100ng／mL rhOPG共培养组（聚乙烯／rhOPG组）及空白对照组。于培养1、3、5、7d取细胞玻片行HE、甲苯胺蓝染色，抗酒石酸酸性磷酸酶（trafrate resistant acid phosphatase，TRAP）染色计数阳性细胞数：皮质骨片行甲苯胺蓝染色并用扫描电镜观察骨片吸收陷窝形态。结果TRAP染色后破骨细胞呈玫瑰红色：培养后5、7d，聚乙烯组阳性染色的破骨细胞与对照组、聚乙烯／rhOPG组比较明显增多，差异均有统计学意义（P〈0．05）；对照组与聚乙烯／rhOPG组比较，差异无统计学意义（P〉0．05）。骨片吸收陷窝甲苯胺蓝染色呈蓝紫色：培养5、7d后，聚乙烯组骨片上的吸收陷窝计数与对照组比较明显增多（P〈0．05）；培养后1、3、5、7d，聚乙烯／rhOPG组骨片上的吸收陷窝计数与聚乙烯组比较，差异均有统计学意义（P〈0．05）。结论rhOPG可抑制聚乙烯颗粒对破骨细胞的刺激作用，可用于防治人工关节置换术后的无菌性关节松动。     

Macrophage colony stimulating factor increases bone resorption in dispersed osteoclast cultures by increasing osteoclast size.

Several reports indicate that macrophage colony stimulating factor (MCSF) is one of the major factors required for osteoclast proliferation and differentiation. Paradoxically, it has also been reported that MCSF inhibits osteoclastic activity. We therefore decided to investigate in detail the effects of MCSF on resorption and osteoclast formation to try and clarify this issue. Osteoclast-containing cultures were obtained from rabbit long bones and cultured on plastic culture dishes or devitalized bovine bone slices. MCSF (4-400 ng/ml) stimulated osteoclastic bone resorption in a time-dependent manner and at all doses examined. After 48 h of culture in the presence of MCSF, we observed a 2-fold increase in the total area of bone resorbed, as well as a significant increase in the area of bone resorbed per osteoclast and the number of resorption pits per osteoclast. This effect was paralleled by an increase in the number of larger osteoclasts (as determined by the number of nuclei per cell) and an increase in the size and depth of the resorption pits. Since the total number of osteoclasts remained the same, the MCSF-induced increase in resorptive activity appeared to be related to an increase in the average size of the osteoclasts. When resorption was expressed as the amount of bone resorbed per osteoclast nucleus, larger osteoclasts resorbed more per nucleus, suggesting that large osteoclasts, as a population, are more effective resorbers than small osteoclasts. Interestingly, when osteoclasts were plated at one-fifth the standard density, the amount of bone resorbed per osteoclast decreased considerably, indicating that resorptive activity is also affected by cell density of osteoclasts and/or of other cells present. However, at this lower density MCSF still increased osteoclast size and resorption by the same fold increase over control, suggesting that the effect of MCSF was independent of factors related to cell density.     

The effect of 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD) on the resorptive function of osteoclasts of known nuclear number

Bisphosphonates (BP) are known to suppress osteoclastic resorption in vivo and in vitro, but doubt persists as to how, and the effect of BP on the resorptive capability of osteoclasts of known nuclear number is unknown. We aimed to find whether the addition of 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD) changed the nuclear profile of an osteoclast population in vitro, and to measure the resorptive efficiency of individually characterized osteoclasts in the presence and absence of the BP. Prehatch chick bone cells were cultured for 24 hours on slices of dentine in medium with or without added APD at 10^-6 M or 10^-8 M, or in control medium on dentine presoaked with 10^-6 M APD for 48 hours. Total pit counts, and pit depths, areas and volumes for pits made by osteoclasts of known nuclear number, were found using confocal video-rate laser reflection microscopy and 3-D image analysis software. APD in the medium inhibited resorption and reduced the volume, area, and depth resorbed per nucleus per chick osteoclast. The nuclear number distribution did not shift significantly, suggesting that no preferential effect arose from the APD affecting one size of cell more than another. The large reduction found in pit numbers, depths, areas, and volumes in the APD dentine-pretreated group supports previous views that BP released during resorption act as metabolic inhibitors, altering protein synthesis by the cell. Larger cells made larger pits, but resorptive efficiency was similar for different cell sizes within the control or APD-treated groups. There was a strong negative correlation between the maximum depth resorbed per nucleus and the number of nuclei in the osteoclast in all groups.     

Inhibition of the classical NF-κB pathway prevents osteoclast bone-resorbing activity

The classical NF-κB pathway plays an important role in osteoclast formation and differentiation; however, the role of NF-κB in osteoclast bone-resorbing activity is not well understood. To elucidate whether NF-κB is important for osteoclast bone-resorbing activity, we used a selective peptide inhibitor of the classical NF-κB pathway named the NBD peptide. Osteoclasts were generated using bone marrow macrophages in the presence of M-CSF and RANKL. The NBD peptide dose-dependently blocked the bone-resorbing activity of osteoclasts by reducing area, volume (p < 0.001) and depths (p < 0.05) of pits. The reduced resorption by the peptide was due to reduced osteoclast bone-resorbing activity, but not reduced differentiation as the number of osteoclasts was similar in all groups. The peptide inhibited bone resorption by reducing TRAP activity, disrupting actin rings and preventing osteoclast migration. Gene expressions of a panel of bone resorption markers were significantly reduced. The NBD peptide dose-dependently reduced the RANKL-induced c-Src kinase activity, which is important for actin ring formation and osteoclast bone resorption. Therefore, these data suggest that the classical NF-κB pathway plays a pivotal role in osteoclast bone-resorbing activity.     

An assay system utilizing devitalized bone for assessment of differentiation of osteoclast progenitors.

The present study provides a novel assay system to examine the differentiation of osteoclast progenitors on devitalized bone slices. We used the population of bone cells liberated enzymatically from 14-day-old mouse embryonal calvariae as a source of osteoclast progenitors. The analysis of differentiation of osteoclast progenitors into preosteoclasts and mature osteoclasts was assessed in terms of the formation of TRAP-positive cells and pits or resorption lacunae, respectively, on devitalized bone slices. Osteoclasts having bone-resorbing activity appeared when the calvarial cell population was cultured in the presence of 1 alpha,25-(OH)2D3 on devitalized bone slices. The resorbing activity increased in a 1 alpha,25-(OH)2D3 dose-related manner. However, calcitonin, a potent inhibitor of differentiation and activation of osteoclast lineage cells, reduced the area of the resorption lacunae in a dose-dependent fashion. The bone-resorbing cells on the bone slices expressed an obvious ruffled border and clear zone, structures specific to mature osteoclasts. These results suggest that osteoclast progenitors in the mouse calvarial population examined differentiated into mature osteoclasts in the presence of 1 alpha,25-(OH)2D3 on devitalized bone slices. Further, using this assay system we assessed the effect of some other osteotropic factors on the differentiation of osteoclast progenitors to mature osteoclasts. IL-1, IL-6, and PTH increased the formation of TRAP-positive cells and pits and the area of resorption lacunae in a dose-dependent fashion. However, prostaglandin E2 was unable to induce the formation of resorption lacunae, although a significant appearance of TRAP-positive cells was observed at a concentration of 200 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ibuprofen inhibits localized bone resorption in the middle ear

Summary Localized osteoclastic bone resorption plays a significant role in the pathogenesis of several diseases of the middle ear as well as orthodontic tooth movement and long bone remodeling. The mechanisms of control of localized bone loss and systemic bone resorption may be different but both may be mediated by a final common pathway which includes prostaglandins. Prostaglandins seem to have a predominantly stimulatory effect on bone resorption, although the exact mechanism is poorly understood. Ibuprofen, a nonsteroidal antiinflammatory drug, is known to inhibit the synthesis of prostaglandins. It is likely that ibuprofen, through its inhibition of prostaglandin synthesis, would decrease the localized osteoclastic bone resorption in a previously described animal model system. Mongolian gerbils were divided into three groups: low dose ibuprofen (10 mg/kg per day), high dose ibuprofen (30 mg/kg per day), and a control group. Following surgical implantation of catheters to the right bullae of each gerbil, pressure was applied for 8 days, stimulating osteoclastic bone resorption. After killing the animals and histomorphometric analysis of the bullae from each, comparisons were made between each group using osteoclast surface (percentage of bone area covered by osteoclasts), osteoclast number (number of osteoclasts/mm bone length), and osteoclast profile area (in μm²). Significantly lower osteoclast surface (Oc. S/BS) was found in pressurized bullae from both treatment groups when compared with pressurized bullae from controls (P<0.05) and significantly lower osteoclast number (N.Oc/T.L) in pressurized bullae from both treatment groups when compared with pressurized bullae from controls (P<0.05). These differences were found to be dose-dependent. No significant differences in individual osteoclast profile area were found in either treatment group when compared with controls.     

Early Response of Bone Marrow Osteoprogenitors to Skeletal Unloading and Sclerostin Antibody

Sclerostin functions as an antagonist to Wnt signaling and inhibits bone-forming activity. We studied the effects of skeletal unloading and treatment with sclerostin antibody (Scl-Ab) on mesenchymal stem cell, osteoprogenitor and osteoclast precursor pools, and their relationship to bone formation and resorption. Male C57BL/6 mice (5-months-old) were hind limb unloaded for 1 week or allowed normal ambulation and treated with Scl-Ab (25 mg/kg, s.c. injections on days 1 and 4) or placebo. Unloading decreased the serum concentration of bone formation marker P1NP (-35 %), number of colony-forming units (CFU) (-38 %), alkaline phosphatase-positive CFUs (CFU-AP+) (-51 %), and calcified nodules (-35 %); and resulted in a fourfold increase in the number of osteoclast precursors. The effects of Scl-Ab treatment on unloaded and normally loaded mice were nearly identical; Scl-Ab increased serum P1NP and the number of CFU, CFU-AP+, and calcified nodules in ex vivo cultures; and increased osteoblast and bone mineralizing surfaces in vivo. Although the marrow-derived osteoclast precursor population increased with Scl-Ab, the bone osteoclast surface did not change, and the serum concentration of osteoclast activity marker TRACP5b decreased. Our data suggest that short-term Scl-Ab treatment can prevent the decrease in osteoprogenitor population associated with skeletal unloading and increase osteoblast surface and bone mineralizing surface in unloaded animals. The anabolic effects of Scl-Ab treatment on bone are preserved during skeletal unloading. These findings suggest that Scl-Ab treatment can both increase bone formation and decrease bone resorption, and provide a new means for prevention and treatment of disuse osteoporosis.     

Polarized osteoclasts put marks of tartrate-resistant acid phosphatase on dentin slices--a simple method for identifying polarized osteoclasts

Osteoclasts form ruffled borders and sealing zones toward bone surfaces to resorb bone. Sealing zones are defined as ringed structures of F-actin dots (actin rings). Polarized osteoclasts secrete protons to bone surfaces via vacuolar proton ATPase through ruffled borders. Catabolic enzymes such as tartrate-resistant acid phosphatase (TRAP) and cathepsin K are also secreted to bone surfaces. Here we show a simple method of identifying functional vestiges of polarized osteoclasts. Osteoclasts obtained from cocultures of mouse osteoblasts and bone marrow cells were cultured for 48 h on dentin slices. Cultures were then fixed and stained for TRAP to identify osteoclasts on the slices. Cells were removed from the slices with cotton swabs, and the slices subjected to TRAP and Mayer's hematoxylin staining. Small TRAP-positive spots (TRAP-marks) were detected in the resorption pits stained with Mayer's hematoxylin. Pitted areas were not always located in the places of osteoclasts, but osteoclasts existed on all TRAP-marks. A time course experiment showed that the number of TRAP-marks was maintained, while the number of resorption pits increased with the culture period. The position of actin rings formed in osteoclasts corresponded to that of TRAP-marks on dentin slices. Immunostaining of dentin slices showed that both cathepsin K and vacuolar proton ATPase were colocalized with the TRAP-marks. Treatment of osteoclast cultures with alendronate, a bisphosphonate, suppressed the formation of TRAP-marks and resorption pits without affecting the cell viability. Calcitonin induced the disappearance of both actin rings and TRAP-marks in osteoclast cultures. These results suggest that TRAP-marks are vestiges of proteins secreted by polarized osteoclasts.