两种纳米形貌对MG63成骨细胞增殖、分化的影响

目的:评价钛表面纳米管和纳米颗粒形貌对MG63成骨细胞的增殖、分化能力的影响。方法:通过磁控溅射和阳极氧化技术制备纳米颗粒和纳米管形貌。采用扫描电镜和轮廓仪表征材料表面形貌以及粗糙度,并将MG63成骨细胞株与不同形貌的钛材料进行复合培养,检测1d、4d、7d的MTT值及4d、7d的碱性磷酸酶活性。结果:培养1d、4d、7d后,纳米管和纳米颗粒组MTT值高于对照组,7d时,纳米管组MTT值高于纳米颗粒组;培养7d后,纳米形貌实验组碱性磷酸酶活性明显高于对照组。结论:纳米管和纳米颗粒形貌均有利于成骨细胞的增殖和分化。相对于纳米颗粒,表面的纳米管形貌更有利于促进成骨细胞的增殖。     

In vivo monitoring of the bone healing process around different titanium alloy implant surfaces placed into fresh extraction sockets

Objectives

Increasing surface roughness and coating with tricalcium phosphate of titanium and titanium alloy implants has been proposed to provide better rates of osseointegration. However, how these changes in surface topography and chemistry influence the osseointegration process of immediate implants placed in fresh extraction sockets is unclear. This study investigated the influence of three clinically employed implant surfaces on the early bone healing events in vivo.

Methods

Machined smooth implants were milled from grade 5 Ti6Al4V titanium. Surfaces were moderately roughened by grit blasting, which were then coated with tricalcium phosphate. Implants were placed into freshly extracted incisor sockets of mandibles of normal Wistar rats and left for 1, 3 and 9 weeks. Healing bone tissue around the implants was examined by histochemistry and immunocytochemistry to localise PCNA proliferative cells, and osteoblast differentiation markers osteopontin and osteocalcin. Positive synthesising cells were counted using image analysis.

Results

Histology indicated no differences in the amount or pattern of bone formation within the healing tissue surrounding the different implant surfaces. Bone healing occurred predominantly on exposed bone surfaces (distance osteogenesis) and not on the implant surface (contact osteogenesis). No differences were observed in the number or timing of PCNA, osteopontin and osteocalcin positive cells within the bone healing tissue around each of the implant analysed.

Conclusion

For immediately placed implants, the surface modifications investigated appeared to have little influence on the activity of bone forming cells surrounding the implant, probably due to the high level of distance osteogenesis seen within this scenario.

Clinical significance

For immediate placement of implants into fresh extraction sockets, titanium implants with roughened surfaces and coating with tricalcium phosphate have negligible influence in accelerating the early bone healing events of osseointegration.     

骨母细胞性肿瘤的免疫组织化学研究

选择３２例骨母细胞性肿瘤，包括１４例良性骨母细胞瘤、２例侵袭性骨母细胞瘤和１６例骨母细胞型骨肉瘤，用ＡＢＣ法作多种抗血清标记（ｖｉｍｅｎｔｉｎ、Ｓ－１００、α－ＡＴ、ｌｙｓｏｚｙｍｅ、Ｌｅｕ－７、Ｋ１２和ＣＥＡ）。结果显示：３２例肿瘤性骨母细胞ｖｉｍｅｎｔｉｎ均呈不同程度的阳性反应；在６例骨母细胞型骨肉瘤和１例侵袭性骨母细胞瘤中散在的单个细胞Ｓ－１００蛋白呈阳性反应，表明肿瘤性的骨母细胞具有软骨分化的潜能１２４例肿瘤中的多核巨细胞α－ＡＴ和１５例肿瘤中的多核巨细胞ｌｙｓｏｚｙｍｅ均呈不同程度的阳性反应，进一步证实这些细胞可能是组织细胞起源；６例骨母细胞型骨肉瘤和４例良性骨母细胞瘤中的骨样基质Ｌｅｕ－７呈阳性反应。     

Effects of PEMF exposure at different pulses on osteogenesis of MC3T3-E1 cells

Objective

Pulsed electromagnetic fields (PEMFs) were considered to be a factor which may affect osteogenesis of osteoblasts, but the effects were diverse with different PEMF parameters. The aim of the current study is to explore the effects of exposure to PEMFs at different pulse number on osteogenesis of osteoblasts.

Design

The mouse osteoblast-like MC3T3-E1 cells were exposed to 0, 400 or 2800 pulses 400 kV/m PEMF and the proliferation, differentiation and mineralization of cells were observed after PEMF exposure by the methods of MTT, biochemical measurement, real-time PCR and Alizarin Red assay.

Results

Compared with 0 pulses groups, the growth curve, alkaline phosphatase (ALP) activity, mRNA level of osteocalcin (OCN) and mineralized nodule formation of MC3T3-E1 cells did not change after 400 pulses PEMF exposure, but decreased after 2800 pulses PEMF exposure. It suggested that under our experimental conditions, only 2800 pulses 400 kV/m PEMF exposure can suppress the proliferation, differentiation and mineralization of MC3T3-E1 cells, but 400 pulses 400 kV/m PEMF exposure cannot.

Conclusions

Pulse number is another involved parameter which may influence the effects of PEMF on osteogenesis of osteoblasts.     

Lipopolysaccharide derived from Aggregatibacter actinomycetemcomitans inhibits differentiation of osteoblasts

Background and objectiveAlveolar bone defects in aggressive periodontitis are generally caused by Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) through osteoclast differentiation facilitated by the interaction between the host's immune system, stimulated by the bacterial outer components of A. actinomycetemcomitans, and osteoblasts. Recently, some reports on the direct effects of A. actinomycetemcomitans on osteoblast differentiation have been published. However, the mechanisms in detail have still remained unknown. We herein demonstrated that A. actinomycetemcomitans might inhibit differentiation of osteoblasts and identified a causative substance.Materials and methodsThe following culture supernatants of A. actinomycetemcomitans were added to mouse osteoblasts, MC3T3-E1: supernatants fractionated by the molecular weight, supernatant supplemented with proteinase K and then heated, and supernatant supplemented with polymyxin B. Subsequently, RNA was extracted to determine the expressions of bone differentiation markers, alkaline phosphatase (ALP), osteocalcin (OCN), and bone sialoprotein (BSP). Additionally, lipopolysaccharide (LPS) was added to MC3T3-E1 culture to measure the markers.ResultsA. actinomycetemcomitans culture supernatant, added to the MC3T3-E1, inhibited the expressions of bone differentiation markers at all concentrations. Only the fraction with a molecular weight of >100 kDa inhibited the bone differentiation. Neither proteinase K nor heating had an effect. However, polymyxin B completely abrogated the differentiation inhibitory activity. A. actinomycetemcomitans LPS concentration dependently inhibited the expressions of the bone differentiation markers.ConclusionsA. actinomycetemcomitans LPS suppressed osteoblast differentiation. This suggests that suppressed bone differentiation is involved in the alveolar bone destruction.     

抗骨质疏松药物作用机制和研发靶点

成骨细胞和破骨细胞功能失衡以及耦联机制的破坏是骨质疏松和代谢性骨病的主要发病机制.抗骨质疏松药物的研发大多通过直接影响此两群细胞的信号和代谢通路而改变其活性.目前成骨细胞信号的研发靶点主要集中在甲状旁腺激素(PTH)通路和Wnt信号通路等,而破骨细胞则主要集中在核因子κB受体激活因子及其配体(RANK/RANKL)通路和整合素αvβ3通路等.     

Piezo1介导的机械应力刺激在抗骨质疏松中的作用

背景：机械敏感通道蛋白Piezo1是机械应力刺激的重要靶蛋白,能将物理的机械力转化成生物电信号,从而调控骨形成与骨吸收,在抗骨质疏松中发挥着重要作用。目的：总结机械应力刺激在抗骨质疏松中的作用机制、Piezo1分子生物学研究进程及Piezo1在骨质疏松中的研究进展。方法：使用计算机在中国知网、万方、维普、Pub Med及Web of Science数据库进行文献检索,中文检索词为“骨质疏松、Piezo1、机械应力、骨”,英文检索词为“osteoporosis,Piezo1,mechanical,osteoblast,osteoclast,chondrocyte,bone”,根据纳排标准对文献进行筛选,最终纳入65篇文献进行综述。结果与结论：(1)机械敏感通道蛋白Piezo1的蛋白结构在冷冻电镜技术突破中不断得到新的解析,目前研究表明Piezo1蛋白基于三叶螺旋桨状三维构造主体,在静默和应激状态下可表现出不同的结构变化;(2)Piezo1介导的机械应力刺激能通过调控成骨细胞、软骨细胞、内皮细胞、肠道细胞的功能影响骨形成,同时调控破骨细胞的功能影响骨吸收,进而在抗骨质疏松中发挥重要作用;(...     

胎兔成骨细胞与bFGF-明胶海绵复合物的体外共建

目的探讨bFGF-明胶海绵复合物作为骨组织工程支架的可行性,为进一步的体内实验提供基础研究。方法取第二代培养的成骨细胞分别与bFGF-明胶海绵复合物及明胶海绵复合培养,进行一般与超微形态学观察,观察细胞生长情况并做成骨细胞碱性磷酸酶(ALP)及微量蛋白含量的测定,比较细胞的粘附能力、增殖活力及成骨活性。结果bFGF-明胶海绵复合物、明胶海绵均可与成骨细胞复合生长,前者的细胞粘附能力、增殖活力及成骨活性均明显优于后者。结论bFGF-明胶海绵复合物能较好的发挥bF- GF作为信号因子的作用,并能提高明胶海绵的相容性,是构建组织工程骨的一种理想的支架材材。     

Wnt signaling and osteoblastogenesis

Wnts are a large family of growth factors that mediate fundamental biological processes like embryogenesis, organogenesis and tumorigenesis. These proteins bind to a membrane receptor complex comprised of a frizzled (FZD) G-protein-coupled receptor (GPCRs) and a low-density lipoprotein (LDL) receptor-related protein (LRP). The formation of this ligand-receptor complex initiates a number of intracellular signaling cascades that includes the canonical/β-catenin pathway, as well as several GPCR-mediated noncanonical pathways. In recent years, canonical Wnt signaling has been shown to play a substantial role in the control of bone formation. Clinical investigations have found that mutations in LRP-5 are associated with bone mineral density and fractures. For example, loss-of-function mutations in LRP-5 cause osteoporosis pseudoglioma syndrome, while gain-of-function mutations lead to high bone mass phenotypes. Studies of knockout and transgenic mouse models for Wnt pathway components like Wnt-10b, LRP-5/6, secreted frizzled-related protein-1, dickkopf-2, Axin-2 and β-catenin have demonstrated that canonical signaling modulates most aspects of osteoblast physiology including proliferation, differentiation, bone matrix formation/mineralization and apoptosis as well as coupling to osteoclastogenesis and bone resorption. Future studies in this rapidly growing area of research should focus on elucidating Wnt/FZD specificity in the control of bone cell function, the role of noncanonical pathways in skeletal remodeling, and direct effects of Wnts on cells of the osteoclast lineage.