小鼠单核巨噬细胞白血病细胞（RAW264.7）的培养及其在诱导破骨细胞中的应用

小鼠单核巨噬细胞白血病细胞(RAW264.7)是通过Abelson鼠白血病病毒诱导BALB/c小鼠产生肿瘤后得到的细胞株。RAW264.7细胞在医学研究中应用十分普遍:它是许多白血病相关研究模型的常用细胞株;在微生物学、免疫学等研究中也十分常用;同时也是小鼠源性破骨前体细胞,可通过特定细胞因子的诱导在体外获得成熟破骨细胞,因此也成为许多骨骼疾病研究的体外模型。但RAW264.7细胞形态和分化状态多变,在实际培养中较难把握,给科研工作带来了一定困难。科研工作者在RAW264.7细胞的培养方法、细胞的形态及分化状态等方面始终观点不一,对于用RAW264.7细胞在体外诱导获得破骨细胞的方法也有许多差别。本文结合文献资料及实践,探索了RAW264.7细胞的培养条件,冻存、复苏、传代方法,以及用核因子κB受体活化因子配基(receptor activator for nuclear factor-κB ligand,RANKL)诱导其成为成熟破骨细胞的技术关键;旨在总结RAW264.7细胞的培养及诱导其分化为破骨细胞的经验教训,探讨RAW264.7细胞的培养和在体外用RANKL诱导RAW264.7细胞分化为破骨细胞的方法、技巧,供广大科研工作者借鉴。     

RANKL诱导小鼠单核细胞RAW264.7分化成成熟破骨细胞

目的观察小鼠的单核／巨噬细胞RAW264．7的一般生物学特征及在RANKL诱导下形成成熟破骨细胞的特征。方法RANKI，诱导RAW264．7细胞6d后，用抗酒石酸酸性磷酸酶(TRAP)染色法观察TRAP阳性多核细胞，吖啶橙染色激光共聚焦显微镜(LCSM)观察多核细胞形态；诱导RAW264．7细胞9d后，RT、PCR检测RAW264．7细胞的破骨细胞表型和功能基因表达及其RANKL诱导后变化；诱导RAW264．7细胞12d后，钙磷覆盖的破骨细胞活性分析板观察破骨细胞的骨吸收功能。结果RAW264．7细胞TRAP染色阴性，单核或2个核，能表达破骨细胞表型和功能基因，无骨吸收功能。RANKL可诱导RAW264．7细胞形成TRAP阳性成熟的多核破骨细胞，上调CathepsinK、CAⅡ、integrinβ3等基因mRNA的表达。结论RAW264．7具有破骨细胞特征性基因表达谱，是一种较好的破骨前体细胞模型。RANKL可诱导RAW264．7细胞形成成熟破骨细胞。     

唑来膦酸抑制RAW264.7细胞系分化的最佳浓度体外实验

目的观察唑来膦酸盐对RAW264.7细胞系毒性作用的浓度范围和抑制RAW264.7分化为破骨细胞的最佳实验浓度。 方法以小鼠前破骨细胞系RAW264.7为研究对象,应用MTT法检测唑来膦酸盐对小鼠前破骨细胞系RAW264.7的毒性作用范围。使用TARP染色法观察不同浓度的唑来膦酸盐作用下破骨细胞的生成数目。 结果体外培养24 h后,酶联免疫反应吸光度结果显示,10^-3 mol/L（0.511±0.920）,10^-4 mol/L（0.615±0.577）唑来膦酸对小鼠前破骨细胞系RAW264.7增殖有毒性作用,与空白对照组（0.789±0.061）相比,差异有统计学意义（F=5.880,P<0.01）。TRAP染色破骨细胞计数结果显示：10^-5 mol/L（8.333±0.817）、10^-6 mol/L（10.400±1.817）、10^-7 mol/L（11.250±2.750）及10^-8 mol/L（11.143±1.864）唑来膦酸盐实验组破骨细胞数与空白对照组破骨细胞数（13.833±2.483）相比,差异具有统计学意义（F=27.972,P<0.05）,且呈浓度依赖性,当唑来膦酸盐浓度为10^-5 mol/L时,抑制效果最明显（P<0.01）。 结论唑来膦酸盐抑制RAW264.7细胞系分化为破骨细胞的最佳体外实验浓度为10^-5 mol/L。     

白细胞介素-21对RAW264.7细胞向破骨细胞分化的影响

目的 了解白细胞介素-21 (IL-21)诱导小鼠巨噬细胞系RAW264.7细胞向破骨细胞分化的作用,并探讨其可能的机制。方法1、以不同浓度IL-21(0,1,10,20,40 ng/ml)处理RAW264. 7细胞,培养5天后进行抗酒石酸酸性磷酸酶(TRAP)染色,Western Blot和免疫组化法检测降钙素受体（CTR)表达,采用Real time PCR法检测CTR和组织蛋白酶（Cathepsin)-K的 mRNA表达水平。2、以信号通路抑制剂AG490、LY294002和PD98059作用30min后再加人IL-21,培养5天后观察破骨细胞形成情况,以Western Blot检测IL-21作用不同时间点时信号通路分子总蛋白和磷酸化蛋白水平,探讨IL-21直接诱导破骨细胞分化的作用机制。结果1、在无RANKL作用的情况下,随着IL-21浓度增加TRAP阳性细胞数逐渐增多,20 ng/ml作用最强,40ng/ml时减弱。IL-21能够诱导破骨标志分子CTR和Cathepsin-K mRNA水平表达上调。Western Blot和免疫细胞化学证实,与阴性组比较,IL-21能促进CTR蛋白水平表达增高。2、PI3K-AKT通路抑制剂（LY294002)可以显著抑制IL-21诱导的 RAW264. 7细胞向破骨细胞分化,IL-21刺激5 ~ 15 min时p-AKT表达增强。结论 IL-21可不依赖RANKL直接诱导小鼠巨噬细胞系RAW264. 7细胞向破骨细胞分化,该作用可能由PI3K-AKT通路介导。     

铁调素对小鼠单核细胞RAW264.7膜铁转运蛋白1（FPN1）表达的影响

目的：观察铁调素对小鼠单核细胞RAW264．7膜铁转运蛋白1（ FPN1）的表达,探讨铁调素对RAW264．7细胞作用的可能通路和机制。方法将不同浓度的铁调素加入含有核因子κB受体活化因子配体（ RANKL）的RAW264．7细胞培养基,24 h后用免疫荧光和Western－blot方法测定FPN1的表达,共聚焦显微镜（ CLSM ）测定细胞内铁离子的浓度。结果 RAW264．7细胞膜上存在FPN1受体的阳性表达;在本实验铁调素浓度干预范围内,FPN1的表达随着铁调素浓度的增加呈浓度依赖性降低（P＜0．05）,同时细胞内铁离子的含量随着铁调素浓度的增加呈浓度依赖性增加（P＜0．05）。结论小鼠单核细胞RAW264．7是铁调素作用的靶细胞,铁调素可通过降解其细胞膜上的FPN1增加细胞内的铁离子。     

IL-6对RAW264. 7细胞成熟分化的体外实验研究

目的探讨研究白介素-6(Interleukin-6,IL-6)对核因子NF-κB受体活化因子配体(Receptor activator of nuclear kappa B ligand,RANKL)及对破骨前体细胞的成熟分化和溶骨效应。方法破骨前体细胞RAW264.7细胞经50ng/mL RANKL诱导1 d后将其分为:1、空白对照组(RANKL+PBS)2、低浓度IL-6组(RANKL+50ng/mL IL-6)3、中浓度IL-6组(RANKL+100ng/mL IL-6)4、高浓度IL-6组(RANKL+150ng/mL IL-6)。连续培养9 d后,进行HE染色检测成熟破骨细胞生成量;通过抗酒石酸酸性磷酸酶(Tartrate resistant acid phosphatase, TRAP)染色法观察TRAP阳性多核细胞的情况;运用扫描电镜检测破骨细胞在骨片上的骨吸收陷窝形成情况。结果 HE染色中,成熟破骨细胞生成量中、高浓度IL-6组明显少于低浓度IL-6组(P0.05),低浓度IL-6组和空白对照组间无明显差别(P0.05)。②通过TRAP染色后,经染色阳性区域面积与视野面积的百分比计算,中、高浓度IL-6组与明显少于低浓度和空白对照组(P0.05)。③扫描电镜观察发现骨吸收陷窝面积与视野面积的百分比随着IL-6浓度的增高,相比空白对照组有显著减少,且高浓度IL-6组中陷窝形成最少(P0.05)。结论 IL-6能直接作用于经RANKL诱导的RAW264.7细胞,能明显抑制破骨细胞激活分化,并降低破骨细胞所致的骨吸收效应。当IL-6浓度超过50ng/mL时,其抑制破骨细胞的骨吸收效应更加明显。     

二甲双胍对破骨细胞体外分化的影响

目的 探讨二甲双胍对破骨细胞体外分化的影响及其可能机制.方法 采用RANKL诱导鼠巨噬细胞系Raw264.7细胞破骨分化模型,给予不同浓度的二甲双胍(400 μmol/L、800 μmol/L和1000μmol/L)和雷帕霉素(100 hmol/L)处理后,通过抗酒石酸酸性磷酸酶(tartrate-resistant Acid Phosphatase,TRAP)染色和破骨细胞骨架结构荧光染色观察破骨细胞数量,骨吸收培养板观察骨陷窝面积,RT-PCR技术检测破骨细胞特异性基因TRAP、组织蛋白酶K、降钙素受体和金属基质蛋白酶-9的表达,ELISA法检测肿瘤坏死因子-α(tumor necrosis factor,TNF-α)表达水平,Western-b1ot检测c-Fos蛋白以及哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin complex l,mTORC1)信号通路下游底物S6K1 Thr389、S6 Ser235/236、4EBP1 Thr37/46的表达及磷酸化水平.结果 二甲双胍和雷帕霉素均可使RANKL诱导的破骨细胞数量减少,抑制破骨细胞特异性基因的表达、抑制TNF-α、c-Fos蛋白以及mTORC1信号通路下游底物S6K1 Thr389、S6 Ser235/236、4E-BP1 Thr37/46的磷酸化,且二甲双胍的抑制作用具有浓度依赖性.结论 二甲双胍可抑制RANKL诱导的破骨前体细胞分化,其机制可能与抑制TNF-α和c-Fos蛋白的生成,以及抑制mTORC1信号通路激活有关.

Abstract：

Objective To investigate the effects of mefformin on the differentiation of osteoclastas well as relative mechanism.Methods Raw264.7 cells from the murine macrophage cell line was used.Receptor activator of NF-κB ligand (RANKL) was used to stimulate osteoclast differentiation from Raw264.7 cells.Osteoclast differentiation was assessed by tartrate-resistant acid phosphatase (TRAP) and actin fluorescence staining and counting the TRAP-positive cells after exposure to different concentrations of mefformin (0 μmol/L,400 μmol/L,800 μmol/L and 1000 μmol/L) or rapamicin (100 nmol/L) in the presence of 50 ng/ml RANKL for 5 days.Bone-resorbing activity was evaluated by BD BioCoatTM OsteologicTM Bone Cell Culture System.The expression of osteoclast-specific genes like TRAP,capthesin K,calcitonin receptor (CTR) and matrix metalloproteinase (MMP-9) was evaluated by RT-PCR.The expression of tumor necrosis factor-α(TNF-ct) S6K1Thr389,S6 Ser235/236,4E-BP1Thr37/46 and c-Fos protein was evaluated by ELISA kit and Western blot analysis,respectively.Results Mefformin dose-dependently inhibited RANKL-stimulated osteoclasts differentiation in Raw264.7 cell culture,as manifested by decrease of TRAP-positive multinucleated cells and pit erosion area,down-regulation of TRAP,cathepsin K,CTR and MMP-9 mRNA and reduction of TNF-α and c-Fos protein expression.Further study revealed that RANKL activated mTOR complex 1(mTORC1) signaling,while mefformin impaired RANKL-stimulated mTORC1 signaling.Rapamycin,an mTORCl-specific inhibitor and immunosuppressive macrolides could also prevent RANKL-induced osteoclast differentiation and bone resorption in vitro.Conclusion Mefformin inhibits osteoclastogenesis in vitro,which may due to reduction of TNF-α and c-Fos protein expression,and mTORC1 signaling is involved in this process.     

Lipopolysaccharide-mediated enhancement of zymosan phagocytosis by RAW 264.7 macrophages is independent of opsonins,laminarin, mannan,and complement receptor 3

Background

Fungal and bacterial coinfections are common in surgical settings; however, little is known about the effects of polymicrobial interactions on the cellular mechanisms involved in innate immune recognition and phagocytosis.

Materials and methods

Zymosan particles, cell wall derivatives of the yeast Saccharomyces cerevisiae, are used to model fungal interactions with host immune cells since they display carbohydrates, including beta-glucan, that are characteristic of fungal pathogens. Using in vitro cell culture, RAW 264.7 macrophages were challenged with zymosan, and phagocytosis determined via light microscopy. The effects of different concentrations of lipopolysaccharide (LPS) on zymosan phagocytosis were assessed. In addition, the transfer of supernatant from LPS-treated cells to naïve cells, the effects of soluble carbohydrates laminarin, mannan, or galactomannan, and the impact of complement receptor 3 (CR3) inhibition on phagocytosis were also determined.

Results

LPS enhanced phagocytosis of zymosan in a dose-dependent manner. Transfer of supernatants from LPS-primed cells to naïve cells had no effect on phagocytosis. Laminarin inhibited zymosan phagocytosis in naïve cells but not in LPS-primed cells. Neither mannan, galactomannan, nor CR3 inhibition had a significant effect on ingestion of unopsonized zymosan in naïve or LPS-treated cells.

Conclusions

Zymosan recognition by naïve cells is inhibited by laminarin, but not mannan, galactomannan, or CR3 inhibition. LPS enhancement of phagocytosis is laminarin insensitive and not mediated by supernatant factors or zymosan engagement by the mannose or CR3 receptors. Our data suggest alternative mechanisms of zymosan recognition in the presence and absence of LPS.     

骨保护素体外抑制小鼠单核巨噬细胞 成熟分化的实验研究

目的研究骨保护素（Osteoprotegerin, 0PG)抑制核因子NF-KB受体活化因子配体（Receptor activator of nuclear kappa B ligand,RANKL)诱导小鼠单核细胞RAW264. 7成熟分化而导致的溶骨效 应。方法50 ng/mL RANKL诱导RAW264. 7细胞1 d后,加人100 ng/mL 0PG(实验组,即0PG + RANKL组）或不加人0PG(对照组,即RANKL组）分别培养7 d和9 d,经细胞形态学观察其变化,抗 酒石酸酸性碟酸酶（Tartrate resistant acid phosphatase, TRAP)染色法观察TRAP阳性多核细胞,扫描 电镜下观察在骨片上的破骨细胞所致的骨吸收陷窝形成情况。结果对照组培养7 d时,在倒置相 差显微镜、透射电镜、光镜下可见细胞形状为椭圆形或不规则形,胞体明显较KAW264.7细胞增大, 胞核多为6 ~ 10个,扫描电镜下还可见大量伪足形成,而实验组培养7 d后,细胞形状多为圆形,且扫 描电镜下未见明显伪足形成;对照组9 d时可见大量TRAP染色阳性的多核巨细胞（含3个或3个以 上的细胞核）,而实验组中TRAP染色阳性的多核破骨细胞偶见多核巨细胞,培养9 d时很难找到多 核巨细胞;仅用RANKL诱导RAW264.7细胞分化7 d时,对照组中破骨细胞表面可见大量伪足伸出, 并形成明显的骨吸收陷窝,实验组中破骨细胞见少许伪足突出,不能看到明显的骨陷窝形成。结论 单用50 ng/mL RANKL体外连续诱导RAWM4.7细胞7 d时,可以促进成熟的破骨细胞显著分化。 100 ng/mL 0PG培养9 d能有效地抑制破骨细胞的分化,减少破骨细胞的骨吸收效应。     

TNF-α及TNF-α抗体对破骨细胞V-ATP酶的影响

目的研究不同浓度的TNF-α及TNF-α抗体对破骨细胞上V-ATP酶表达量的影响。方法体外诱导小鼠RAW264.7细胞分化为破骨细胞,通过抗酒石酸酸性磷酸酶染色检测破骨细胞生成情况。然后将破骨细胞分为对照组、TNF-α干预组及TNF-α抗体干预组,TNF-α干预组、TNF-α抗体干预组分别用低、中、高三种浓度的TNF-α、TNF-α抗体干预48 h。用实时荧光定量聚合酶链反应(real-time PCR)、Western blot检测破骨细胞V-ATP酶的mRNA和蛋白表达水平。结果 TRAP染色检测提示有多核破骨细胞生成。TNF-α处理组V-ATP酶mRNA表达水平显著高于对照组(P0.001);TNF-α抗体处理组V-ATP酶mRNA表达水平显著低于对照组(P0.001)。同时,TNF-α处理组V-ATP酶蛋白表达水平显著高于对照组(P0.05);TNF-α抗体处理组V-ATP酶蛋白表达水平显著低于对照组(P0.05)。结论 TNF-α可提高破骨细胞V-ATP酶的表达;TNF-α抗体可抑制破骨细胞V-ATP酶的表达。上述提示TNF-α可能通过提高破骨细胞V-ATP酶的表达从而增加破骨细胞的骨吸收作用。     

The number of tartrate-resistant acid phosphatase-positive osteoclasts on neonatal mouse parietal bones is decreased when prostaglandin synthesis is inhibited and increased in response to prostaglandin E2, parathyroid hormone,and 1,25 dihydroxyvitamin D3

The culture of parietal bones from 4-day old mice in indomethacin (Ind) for 1 day caused a large reduction in the number of tartrate-resistant acid phosphatase positive osteoclasts (TRAP+OC) relative to both control bones and to freshly isolated bones. This reduction did not occur if prostaglandin E₂ (PGE₂) was present. When 5-bromo-2-deoxyuridine (BDU) was injected into 4-day old mice, newly formed TRAP+OC nuclei became labeled 1 day later; these bones were then cultured with Ind for 1 day. TRAP+OC and newly labeled TRAP+OC nuclei were commensurately decreased in number. This suggests an active down-regulation rather than merely the inhibition of new TRAP+OC formation. Incubation of bones with Ind and either PGE₂, parathyroid hormone, or 1,25 dihydroxyvitamin D₃ for 6 hours following a 1-day preincubation in Ind, resulted in an increase in TRAP+OC compared with Ind alone. Using BDU labeling in vitro and in vivo, we show that this increase in number of TRAP+OC is not the result of cell proliferation, but rather differentiation of postmitotic precursors.This work has been presented in part as an abstract to the Bone and Tooth Society Summer meeting, July 1993     

The origin of osteoclasts: An immunohistochemical study on macrophages and osteoclasts in embryonic rat bone

Summary The origin of osteoclasts was studied in embryonic rat bone primordia using a set of monoclonal antibodies (ED1, ED2, and ED3) that exclusively recognize monocytes and macrophages. ED1 recognizes monocytes and macrophages. Mononuclear phagocytes which were ED1 positive were found in the perichondrium/periosteum of developing bone. These cells started to infiltrate the primordia when the cartilage became hypertrophic. During bone formation, multinucleated ED1-positive cells with the morphological characteristics of osteoclasts were found in the developing bone marrow cavity and against the bone collar. The present findings support the notion that osteoclasts arise by fusion of mononuclear phagocytes derived from blood monocytes.     

Inhibition of prostaglandin synthesis leads to a change in adherence of mouse osteoclasts from bone to periosteum

When mouse parietal bones were incubated for 1 day in medium containing indomethacin (Ind), the number of tartrate-resistant acid phosphatase-positive osteoclasts (TRAP+OC) counted on the bone surface was drastically reduced. This reduction did not occur with calcitonin or if the endocranial membrane (periosteum) was removed prior to incubation with Ind. The aim of this work was to determine the mechanism involved. TRAP+OC were found to be increased on the endocranial membrane adjacent to the resorbing surface after Ind treatment, compared with cultures supplemented with parathyroid hormone (PTH) or prostaglandin E2 (PGE2). However, this increase accounted for only half of those lost from the bone surface. TRAP negative osteoclasts were also seen on the membrane and, to a lesser extent, on the bone. Increased TRAP specific activity could be extracted from the endocranial membranes of bones incubated with Ind compared with PGE2 controls. When bones that had been exposed to Ind were then cultured for 1 day in PGE2, an increase in TRAP+OC occurred. This increase was blocked by the removal of the endocranial membrane prior to incubation with PGE2. We conclude that when prostaglandin production ceases, TRAP+OC become less adherent to bone and more adherent to the endocranial membrane. Stimulators of bone resorption appear to reverse this process. Received: 1 September 1995 / Accepted: 12 February 1996     

阿仑膦酸盐诱导破骨细胞调亡FAS基因的表达

本研究采用１０－８Ｍ１，２５（ＯＨ）２Ｄ３诱导ＳＤ鼠骨髓细胞形成破骨细胞，通过检测细胞上ＦＡＳ基因的表达，探讨骨吸收因子阿仑膦酸盐的作用机制。骨髓细胞培养６天即有多核巨细胞形成，加入阿仑膦酸盐致终浓度为１００μＭ，继续培养４８小时后，发现用药组破骨样细胞及圆形单核细胞的前体细胞呈现凋亡的形态学特征：胞浆收缩，核固缩等。ＦＡＳ抗原是与细胞凋亡密切相关的细胞表面蛋白，用抗ＦＡＳ抗体免疫组化方法，检测凋亡的破骨细胞及其前体细胞上ＦＡＳ基因的表达，结果呈阳性，而未凋亡细胞呈阴性，提示阿仑膦酸盐导致的破骨细胞及其前体细胞的凋亡，可能与细胞表面的ＦＡＳ基因表达相关     

Production of IL-7 is increased in ovariectomized mice,but not RANKL mRNA expression by osteoblasts/stromal cells in bone,and IL-7 enhances generation of osteoclast precursors in vitro

Osteoclastogenic cytokines produced by T and B lineage cells and interleukin (IL)-7-induced expansion of the pool size of osteoclast precursors have been suggested to play an important role in acceleration of osteoclastogenesis induced by estrogen deficiency. However, the contribution of increased RANKL produced by osteoblasts/stromal cells to increase osteoclastogenesis in a mouse model of estrogen-deficient osteoporosis and in vitro effects of IL-7 on osteoclast precursor generation remain controversial. Thus, we investigated the effect of ovariectomy (OVX) of mice on production of RANKL, osteoprotegerin (OPG), and IL-7 in bone and the effect of IL-7 on osteoclast precursor generation in vitro. OVX did not significantly stimulate mRNA expressions of RANKL and OPG in whole femurs. Because the epiphysis, but not the femoral shaft (diaphysis) or bone marrow, is the main site of osteoclastogenesis, it is important to specifically analyze mRNA expression by osteoblasts/stromal cells at these parts of the femur. Therefore, we isolated RNA from bone marrow cell-free epiphysis, diaphysis, and flushed-out bone marrow and examined mRNA expression. The results showed no significant changes of RANKL and OPG mRNA expression in any part of the femur. In addition, OVX did not significantly affect RANKL and OPG mRNA expression by the adherent stromal cells isolated from flushed-out bone marrow cells but did stimulate RANKL mRNA expression by B220⁺ cells in the nonadherent cell fraction. On the other hand, OVX increased IL-7 mRNA expression in the femur as well as IL-7 concentrations in bone fluid. In cultures of unfractionated bone cells isolated by vigorous agitation of minced whole long bones to release the cells tightly attached to the bone surfaces, but not in cocultures of clonal osteoblasts/stromal cells and flushed-out bone marrow cells, IL-7 stimulated generations of osteoclasts as well as osteoclast precursors. These data suggest that increased RANKL production by osteoblasts/stromal cells is unlikely to play a central role in acceleration of osteoclastogenesis in estrogen deficiency of mice and that IL-7 stimulates osteoclast precursor generation, presumably through an action of IL-7 on the cells attached to bone rather than on cells contained in the bone marrow cell population.     

Cytological and functional studies of preosteoclasts and osteoclasts in the alveolar bones from neonatal rats using microperoxidase as a tracer

Summary Microperoxidase (MP) was used to investigate the cytological and functional features of preosteoclasts and osteoclasts during rat alveolar bone development. We observed mononuclear cells as preosteoclasts and multinuclear cells with and without ruffled borders (RB). In the bone facing multinuclear cells with RB as active osteoclasts, MP was extensively deposited along the external bone matrix undergoing resorption, and was phagocytosed with bone components into the vacuoles of osteoclasts. Neither preosteoclasts nor multinuclear cells without RB took up MP and bone components. Only multinuclear cells with RB seemed to resorb bone. Monocytes/macrophages (MMP) phagocytosed MP through all regions of the plasma membrane, whereas osteoclasts took up MP only through the RB which was a part of the plasma membrane. Endogenous peroxidase was detected in the MMP but not in preosteoclasts and osteoclasts. Thus, osteoclasts were considerably different from the MMP. The numbers of MMP were extremely few close to the osteoclasts, whereas moderate numbers of preosteoclasts were located close to the osteoclasts. Except for the nucleus and RB, there were many morphological similarities between preosteoclasts and osteoclasts. We therefore suggest that preosteoclasts, rather than MMP, are the precursors of osteoclasts during alveolar bone development of neonatal rats.     

The type II collagen N-propeptide, PIIBNP, inhibits cell survival and bone resorption of osteoclasts via integrin-mediated signaling

Objective

Type IIB procollagen is characteristic of cartilage, comprising 50% of the extracellular matrix. The NH₂-propeptide of type IIB collagen, PIIBNP, can kill tumor cells via binding to integrins α_Vβ₃ and α_Vβ₅. As osteoclasts rely on α_Vβ₃ integrins for function in bone erosion, we sought to determine whether PIIBNP could inhibit osteoclast function.

Methods

We undertook in vitro and in vivo experiments to evaluate both osteoblast and osteoclast functions in the presence of recombinant PIIBNP. Adhesion of osteoclasts to PIIBNP was analyzed by staining of attached cells with crystal violet. PIIBNP-induced cell death was evaluated by counting Trypan Blue stained cells. The mechanism of cell death was evaluated by DNA fragmentation, TUNEL staining and western blotting to detect cleaved caspases. To determine the role of α_Vβ₃ integrin, osteoclasts were pretreated with α_V or β₃ integrin specific siRNA before the treatment with PIIBNP. To explore PIIBNP function in vivo, a lipopolysaccharide-induced mouse calvaria lysis model was employed.

Results

Osteoclasts adhered to PIIBNP via an RGD-mediated mechanism. When osteoclasts were plated on extracellular matrix proteins, PIIBNP induced apoptosis of osteoclasts via caspase 3/8 activation. Osteoblasts and macrophages were not killed. Reduction of α_V or β₃ integrin levels on osteoclasts by siRNA reduced cell death in a dose-dependent manner. In vivo, PIIBNP could inhibit bone resorption.

Conclusion

We conclude that PIIBNP can inhibit osteoclast survival and bone resorption via signal transduction through the α_Vβ₃ integrins. Because of this property and the cell specificity, we propose that PIIBNP may play a role in vivo in protecting cartilage from osteoclast invasion and also could be a new therapeutic strategy for decreasing bone loss.     

无血清培养骨髓基质干细胞向神经细胞诱导分化条件的优化

目的：探索无血清培养的骨髓基质干细胞（BMSCs）向神经细胞诱导分化条件的优化方案,为BMSCs应用于脊髓损伤的临床治疗创造条件.方法：用含2% Utroser G的UltraCULTURE无血清培养体系体外扩增人BMSCs,采用流式细胞仪检测培养细胞的表面标志,再以全反式维甲酸、β-巯基乙醇和神经生长因子为主要成分组成6种诱导液诱导BMSCs向神经细胞分化,镜下观察细胞形态学变化,用抗人β微管蛋白（β-Tubulin）抗体和抗人胶质纤维酸性蛋白（GFAP）抗体进行免疫荧光染色鉴定诱导后的神经细胞,通过流式细胞仪检测诱导后细胞的凋亡率.结果：无血清培养的BMSCs在6种诱导条件下均可不同程度地分化为神经样细胞,镜下可见诱导后细胞表现为神经细胞形态特征,免疫荧光染色显示β-Tubulin和GFAP均有阳性表达,诱导后细胞发生不同程度的凋亡,其中全反式维甲酸和神经生长因子组成的复合诱导液的诱导效率较高,诱导后细胞凋亡率较低.结论：全反式维甲酸与神经生长因子联合应用可在体外高效、稳定地诱导无血清培养的BMSCs分化为神经样细胞,是较佳的诱导条件.     

rhIGF-1对成骨细胞增殖、分化及骨保护素、骨保护素配体基因mRNA表达的影响

目的 观察不同剂量rhIGF-1对成骨细胞增殖，分化及骨保护素，骨保护素配体mRNA基因表达的影响，为明确骨保护素，骨保护素配体在骨质疏松症发病的作用机理及rhIGF-1在临床中应用提供实验依据。方法 取2代培养的大鼠成骨细胞，在rhIGF-1为0ng/ml,10ng/ml,20ng/ml,50ng/ml的浓度中培养。观察细胞的生长及钙结节的形成，MTT法，碱性磷酸酶（ALP），骨钙素（OCN）测定细胞增殖和分化，RT－PCR测定rhIGF-1对成骨细胞骨保护素，骨保护素配体基因mRNA表达的影响。结果 成骨细胞在7d可铺满瓶壁，30d可形成钙结节，rhIGF-1可促进成骨细胞的增殖，ALP和OGN的分泌，促进骨保护素，骨保护素配体基因的表达，以促进骨保护素表达明显，在rhIGF-1为10ng/ml时作用明显。结论 rhIGF-1可促进大鼠成骨细胞的增殖，分化，及骨保护素，骨保护素配体基因mRNA的表达，骨保护素mRNA表达显。rhIGF-1可能通过影响骨保护素，骨保护素配体而调节成骨细胞破骨细胞的平衡，使骨重建，从而防治骨质疏松症。