p38MAPK在17β-雌二醇和雷洛昔芬促成骨细胞増殖和分化中的作用

目的:观察p38MAPK信号转导通路在17β-雌二醇和雷洛昔芬促成骨细胞增殖和分化过程中的作用。方法:取第一继代BALB/c小鼠头盖骨成骨细胞,药物刺激组分别加入不同浓度17β-雌二醇或雷洛昔芬;含阻断剂组预先添加不同浓度的SB202190(p38MAPK的阻断剂)阻断信号转导通路,再加17β-雌二醇或雷洛昔芬,作用72h后用MTT法与PNPP法测定细胞的增殖能力和碱性磷酸酶活性。结果:加入雌激素或雷洛昔芬后,成骨细胞的增殖和分化明显增强,与空白对照组比较差异具有显著性意义(P<0·05);阻断p38MAPK信号转导通路后,细胞增殖分化受到明显抑制,与未阻断组比较差异具有非常显著性意义(P<0.01)。结论:p38MAPK在17β-雌二醇和雷洛昔芬诱导的小鼠成骨细胞的増殖和分化过程中发挥重要作用。     

Temporal Pattern of Stimulation of Osteoblast-Associated Genes During Mechanically-Induced Osteogenesis In Vivo: Early Responses of Osteocalcin and Type I Collagen

Mechanical loading is an essential environmental factor in skeletal homeostasis, but the response of osteoblast-associated genes to mechanical osteogenic signal is largely unknown. This study uses our recently characterized in vivo osteoinductive model to analyze the sequence of stimulation and the time course of expression of osteoblast-associated genes in mechanically loaded mouse periodontium. Temporal pattern of regulation of osteocalcin (OC), alkaline phosphatase (ALP), and type I collagen (collagen I) was determined during mechanically-induced osteoblast differentiation in vivo, using a mouse tooth movement model earlier shown to induce bone formation and cell-specific regulation of genes in osteoblasts. The expression of target genes was determined after 1, 2, 3, 4, and 6 days of orthodontic movement of the mouse first molar. mRNA levels were measured in the layer of osteoblasts adjacent to the alveolar bone surface, using in situ hybridization and a relative quantitative video image analysis of cell-specific hybridization intensity, with non-osseous mesenchymal periodontal cells as an internal standard. After 24 hours of loading, the level of OC in osteoblasts slightly decreased, followed by a remarkable 4.6-fold cell-specific stimulation between 1 and 2 days of treatment. The high level expression of OC was maintained throughout the treatment with a peak 7-fold stimulation at day 4. The expression of collagen I gene was not significantly affected after 1 day, but it was stimulated 3-fold at day 2, and maintained at a similar level through day 6. The ALP gene, which we previously found to be mechanically stimulated during the first 24 hours, remained enhanced from 1.8- to 2.2-fold throughout the 6 days of treatment. Thus, in an intact alveolar bone compartment, mechanical loading resulted in a defined temporal sequence of induction of osteoblast-associated genes. Stimulation of OC 48 h after the onset of loading (and 24 h prior to deposition of osteoid) temporally coincided with that of collagen I, and was preceded for 24 h by an enhancement of ALP. Identification of OC as a mechanically responsive gene induced in functionally active osteoblasts in this study is consistent with its potential role in limiting the rate of mechanically-induced bone modeling. Furthermore, these results show that temporal progression of mechanically-induced osteoblast phenotype in this in vivo model occurs very rapidly. This suggests that physiologically relevant mechanical osteoinductive signal in vivo is targeting a population of committed osteoblast precursor cells that are capable of rapidly responding by entering a differentiation pathway and initiating an anabolic skeletal adaptation process.     

动态轴向压应变促进丝素蛋白支架内MC3T3-E1细胞成骨分化

目的 观察动态轴向压应变对三维丝素蛋白支架内成骨细胞成骨相关基因表达的影响。方法 应用动态力学加载仪对实验组小鼠胚胎成骨细胞MC3T3-E1加载动态轴向压应变（5%应变幅度,1 Hz,30 min/d,共21 d）,对照组细胞常规静置培养,不施加力学刺激。应用定量PCR检测细胞成骨基因碱性磷酸酶（ALP）、I型胶原（COLⅠ）、骨特异性转录因子（Runx2）、成骨相关转录因子（Osx）、骨钙蛋白（OCN） mRNA表达量。结果 成骨细胞在周期性轴向压应力刺激下,Runx2、Osx及COLⅠ表达分别增加280%、68.9%和79.6%,ALP及OCN表达也分别增加10.7%和26.9%。实验组成骨相关基因mRNA表达与对照组比较,差异具有统计学意义（P<0.05）。结论 成骨细胞复合丝素蛋白生物支架材料在周期性轴向压应力刺激下,成骨基因COLⅠ、Runx2、Osx及OCN表达明显上调,可能是生理状态下压应力刺激促进骨折愈合的重要机制之一。研究结果对于以力学信号为基础的细胞疗法修复骨缺损等疾病具有重要临床价值。     

金雀异黄酮对成骨细胞增殖的影响及其可能的分子生物学机制

目的观察金雀异黄酮（GS）对绝经期骨质疏松患者骨膜成骨细胞增殖的影响及其分子生物学机制。方法用噻唑蓝比色法和流式细胞术分别检测GS对成骨细胞增殖活力和细胞周期分布的影响；Western—blot技术分析GS对细胞周期蛋白D和E表达的影响。结果GS可显著提高成骨细胞增殖活力，与溶剂对照组比较，10^-8mol／L、10^-7mol／L和10^-6mol／L GS时，细胞增殖率分别为137％、155％和161％；提高S期和M／G2期细胞分布比例，并伴有G0／G1期细胞比例降低；它莫西芬可抑制10^-7mol／L和10^-6mol／L GS促成骨细胞增殖效应。Western—blot的检测结果显示，10^-8mol／L和10^-7mol／L GS对成骨细胞处理24h，提高细胞周期蛋白D和E蛋白质的表达（P〈0．05）。结论由于雌激素受体拮抗剂它莫西芬可抑制GS对成骨细胞的促增殖作用，表明金雀异黄酮可通过激活雌激素受体途径，表现出雌激素效应，并促进骨组织代谢中的骨形成作用。     

Establishment of a Rat Long-Term Culture Expressing the Osteogenic Phenotype: Dependence on Dexamethasone and FGF-2

Rat stromal bone-marrow cells cultured in the presence of dexamethasone, ascorbic acid, &#103 -glycerophosphate, and fibroblast growth factor-2 (FGF-2) express the osteogenic phenotype (Pitaru et al., J. Bone Miner. Res . 8:919-929, 1993). The purpose of this study was to establish a long-term homogeneous culture expressing the osteogenic phenotype. The cultures were routinely passaged every 5 days in the absence or presence of either or both dexamethasone and FGF-2, and the cumulative doubling number and the expression of the osteogenic phenotype were determined. Cultures treated with dexamethasone (10 &#109 7 M) ceased proliferation and only upon addition of FGF-2 (3 ng/ml) was a spontaneous immortalization achieved, as expressed by sustained proliferation for about 1 year, with a doubling time of 22 h and more than 300 doublings in 72 passages. Both FGF-2 and dexamethasone are required and act synergistically to maintain cell propagation, alkaline phosphatase expression, and osteocalcin secretion; however, protein content was FGF-2 dependent and the mineralization was dexamethasone dependent. Repetitive single-cell cloning tested the homogeneity and stability of the cells expressing the osteogenic phenotype in these long-term cultures. It was shown that 25% to 50% of subclones derived from clones with an osteogenic phenotype do not further express the osteogenic phenotype. In conclusion, we have established a spontaneously immortalized dexamethasone- and FGF-2-dependent rat stromal bone-marrow-derived long-term culture expressing the osteogenic phenotype. The cultures tend to lose the osteogenic phenotype, and dexamethasone supports the long-term preservation of the osteogenic phenotype.     

Placenta Hominis Protects Osteoporosis in Ovariectomized Rats

In China, Japan, and Korea, placenta hominis extracts (PHEs) are used clinically for the treatment of osteoporosis. The anti-osteoporotic effect of PHEs was studied. The trabecular bone area and thickness in OVX rats decreased by 50% from those in sham-operated rats; these decreases were completely inhibited by administration of PHEs for 7 weeks. Osteoclast numbers and the osteoblast surface were enhanced in OVX rats, but PHEs had no effect on these phenomena. Serum phosphorus and alkaline phosphatase in OVX rats increased compared to those in sham-operated rats, but the increases were not affected by the administration of PHEs. Thyroxine (T₄) level was stimulated in OVX rats. The extracts inhibited the T₄ level in the OVX rats. These results strongly suggest that PHEs be effective in preventing the development of bone loss induced by OVX in rats.     

MiR-183 regulates the differentiation of osteoblasts in the development of osteoporosis by targeting Smad4

ObjectiveTo discuss the effect of miR-183 on osteoblast differentiation in the osteoporosis progression via targeting Smad4.MethodsOsteoporosis models were constructed on ovariectomized (OVX) mice to determine the expression of miR-183 and Smad4. Then, MC3T3-E1 cells and primary osteoblasts were divided into Mock, miR-control, miR-183 mimic, miR-183 inhibitor, siSmad4 and miR-183 inhibitor + siSmad4 groups. Alkaline phosphatase (ALP) staining were performed to determine ALP activity, alizarin red staining to evaluate the calcium deposit, while qRT-PCR and Western blotting were used to determine the expression of related molecules. Besides, MC3T3-E1 cells transfected with miR-control or miR-183 mimic were cultured with or without TGF-β1 to verify whether miR-183 regulates the TGF-β signaling pathway.ResultsMiR-183 was up-regulated with decreased Smad4 in the femur of OVX mice, and dual luciferase reporter gene assay showed that Smad4 was a target of miR-183. As compared to Mock group, MC3T3-E1 cells and primary osteoblasts in the miR-183 mimic group and siSmad4 group had significant reductions of OCN, OPN, Runx2 and Osx, as well as decreased ALP activity and calcium deposit. Contrarily, miR-183 and Smad4 were up-regulated and down-regulated respectively. However, cells in the miR-183 inhibitor group manifested the opposite changes. Besides, osteoblast differentiation in the miR-183 inhibitor + siSmad4 group was weakened evidently when compared to miR-183 inhibitor group. Pathway analysis indicated that miR-183 regulated osteogenic differentiation via TGF-β signaling pathway.ConclusionMiR-183 was up-regulated in osteoporosis, and miR-183 overexpression can inhibit osteoblast differentiation by targetedly down-regulating TGF-β pathway member Smad4 to trigger osteoporosis.     

Benchtop plasma treatment of titanium surfaces enhances cell response

ObjectiveModifications to implant surface properties, including topography, chemistry, and wettability, alter immune response, osteoblast differentiation of bone marrow stromal cells (MSCs), and implant integration in vivo. Dielectric barrier discharge (DBD) plasma treatment has been used to sterilize surfaces and remove adsorbed carbon, improving wettability. However, unless it is used immediately prior to placement, ambient atmospheric hydrocarbons rapidly adhere to the surface, thereby reducing its hydrophilicity. Moreover, this method is not practical in many clinical settings. The aim of this study was to evaluate the effectiveness of an on-site benchtop modification technique for implants at time of placement, consisting of a DBD plasma that is used to sterilize implants that are pre-packaged in a vacuum. Effects of the plasma-treatment on implant surface properties and cellular response of MSCs and osteoblasts were assessed in vitro.MethodsTitanium-aluminum-vanadium implant surfaces were grit-blasted (GB) or grit-blasted and acid-etched (AE), and packaged under vacuum. AE surfaces were also plasma-treated using the benchtop device (GB + AE) and then removed from the vacuum. GB surface morphology was altered with AE but AE microroughness was not changed with the plasma-treatment. Plasma-treatment increased the surface wettability, but did not alter surface atomic concentrations of titanium, oxygen, or carbon.ResultsMSCs and osteoblast-like cells (MG63 s) produced increased concentrations of osteocalcin, osteopontin, and osteoprotegerin after plasma-treatment of AE surfaces compared to non-plasma-treated AE surfaces; production of IL6 was reduced and IL10 was. Aging GB + AE surfaces for 7 days after plasma-treatment but still in the vacuum environment reduced the effectiveness of plasma on cellular response.SignificanceOverall, these data suggest that application of benchtop plasma at the time of implant placement can alter the surface free energy of an implant surface without modifying surface chemical composition and enhance the differentiation and activity of MSCs and osteoblasts that are in contact with these implant surfaces.     

乳铁蛋白促进成骨细胞增殖的最佳浓度及促进分化的最佳时间

目的 探索乳铁蛋白促进大鼠成骨细胞增殖的最佳浓度及1000μg/mL乳铁蛋白对促进成骨细胞分化的最佳时间。方法 用混合酶消化法分离大鼠颅盖骨成骨细胞进行原代培养;不同浓度乳铁蛋白干预成骨细胞,浓度分别为0、0.1、1、10、100、200、400、600、800和1000μg/mL,在1、3、5、7d后分别采用CCK-8法测定细胞增殖;用1000μg/mL的乳铁蛋白干预成骨细胞7、14、21d后,采用碱性磷酸酶染色法检测细胞内碱性磷酸酶的活性。结果 1.CCK-8法测定细胞增殖结果显示,低于100μg/mL浓度乳铁蛋白组其OD值随着浓度的增高而增高,而高于100μg/mL浓度乳铁蛋白组其OD值随着乳铁蛋白浓度的增高而递减;2.碱性磷酸酶染色法结果显示,1000μg/mL的乳铁蛋白在干预第21天时碱性磷酸酶活性最高。结论 100μg/mL乳铁蛋白是促进大鼠成骨细胞增殖的最佳浓度;1000μg/mL的乳铁蛋白促进成骨细胞分化作用呈时间依赖性。