High-magnitude mechanical strain inhibits the differentiation of bone-forming rat calvarial progenitor cells

Purpose: Orthodontic tooth movement occurs during the bone remodeling induced by therapeutic mechanical strain. It is important to investigate the relation between the strength of mechanical stress and bone formation activity. The aim of this study was to determine the effect of high-magnitude mechanical strain on bone formation in detail.

Materials and methods: Osteoblast-like cells isolated from fetal rat calvariae were loaded with 18% cyclic tension force (TF) for 48?h. To phenotypically investigate the effect of TF, we measured the number and the size of bone nodules stained by von Kossa technique on day 21 after cell seeding and determined the calcium content of bone nodules on day 14. Furthermore, we examined the gene expression of BMP-2, Runx2 and Msx2, which are important factors for bone nodule formation, on days 1, 4 and 7 after TF loading.

Results: The maximum bone nodule size in the control group was 1620 and 719?μm in the TF group. Furthermore, the mean number of bone nodules sized over 360?μm in the TF group was significantly decreased compared to the control group. The calcium content was also significantly decreased to 42% by TF loading. The mRNA expression of BMP-2, Runx2 and Msx2 was decreased 1 and 4 days after TF loading.

Conclusion: The differentiation of bone forming progenitor cells into bone nodule forming cells was inhibited by TF due to the decreased expression of bone formation related factors such as BMP-2, Runx2 and Msx2.     

体外培养的人脂肪间充质干细胞生物学特性的研究

目的:了解体外培养的人脂肪间充质干细胞的生物学特性及其体外成脂和成骨的能力.方法:体外培养人脂肪间充质干细胞并传代计数,行成骨和成脂诱导,流式细胞仪检测其细胞增殖周期与表面分子.结果:人脂肪干细胞经过体外培养均一的阳性表达CD44、CD106,而CD49d、CD34、CD45和HLA-DR表达阴性.细胞周期分析表明:G0/G1、S和G 2/M所占比例分别为79.1%、19.7%和1.3%.分离细胞在诱导体系下可以向成骨和成脂方向分化.结论:脂肪间充质干细胞具有特殊的生物学特点,体外能够向成骨和成脂方向分化.     

In vitro characterization of peptide-modified p(AAm-co-EG/AAc) IPN-coated titanium implants.

Interpenetrating polymer networks (IPNs) of poly(acrylamide-co-ethylene glycol/acrylic acid) [p(AAm-co-EG/AAc)] functionalized with an -Arg-Gly-Asp- containing peptide derived from rat bone sialoprotein [bsp-RGD(15)] were grafted to titanium implants in an effort to modulate osteoblast behavior in vitro. Surface characterization data were consistent with the presence of an IPN, and ligand density measurements established that the range of peptide density on the modified implants spanned three orders of magnitude (0.01-20 pmol/cm2). In vitro biological characterization of the modified implants employing the primary rat calvarial osteoblast (RCO) model resulted in the identification of a critical ligand density (0.01osteoblast phenotype. After 14 and 21 days, mineralization was greater on the 0.1 and 10 pmol/cm2 bsp-RGD(15) modified implants compared to the base titanium and other control surfaces. The observed effects were attributed to specific interactions with bsp-RGD(15) and support the concept that peptide-modified implants can enhance the kinetics of differentiation of the cells they contact. These results suggest that in vivo biological performance evaluation of these biomimetic implant surfaces is merited.     

骨髓基质干细胞-藻酸钙复合物构建骨组织的实验研究

目的 研究犬骨髓基质干细胞(BMSCs)体外成骨活性和在犬体内异位成骨能力，探讨其作为骨组织工程种子细胞的可能性。方法 抽取成年犬骨髓，梯度离心法获取单个核细胞，条件培养液体外培养、诱导、扩增后，进行组织化学、免疫细胞化学染色，透射电镜下观察其成骨活性。将培养的第3代细胞与藻酸钙所形成的复合物植于犬皮下，3月后行组织学检测。结果 体外培养的BMSCs Von Kossa染色可见钙结节，AKP染色及I型胶原、Osf2／Cbfαl、骨钙素免疫细胞化学染色先后呈现阳性；透射电镜下见基质钙化；组织学检测提示细胞一藻酸钙复合物体内培养3月后形成骨样组织。结论 BMSCs在大量扩增的同时，在一定条件下能向成骨细胞分化，细胞与藻酸钙复合物能在具免疫力的哺乳动物皮下形成骨样组织。BMSCs可作为骨组织工程较理想的种子细胞。     

60Coγ射线对体外培养成骨细胞作用的实验研究

目的：研究放射性骨损伤的发病机制，探讨骨折合并射线损伤愈合能力下降的原因。方法：将体外培养的成骨细胞用^60Coγ射线一次性照射3、6、9、12Gy，以建立体外培养成骨细胞受射线作用的实验模型；同时，观察成骨细胞的碱性磷酸酶（ALP）活性改变，骨形态发生蛋白（BMP）和转化生长因子β1（TGF-β1）的胞质内表达量，以及细胞内钙离子的含量。结果：成骨细胞受射线照射后，其ALP活性明显降低，且与照射剂量呈明显量效关系，3Gy组抑制率为31.59%，而12Gy组则为84.95%；BMP、TGF-β1的表达量下降，但与照射剂量无明显量效关系；胞质内钙含量亦降低，但受照各组间的抑制率无明显统计学差异。结论：射线对成骨细胞具有直接损害作用，放射性骨损伤的重要方面就是射线对成骨细胞的主要功能酶ALP活性的损害，抑制BMP、TGF-β1等生长因子的合成，且干扰细胞内第二信使钙离子，从而致骨组织的再生重建机能下降。     

诱导成骨的组织学及超微结构

选用免32只,手术截除桡骨2cm。缺损区充填DGB,手术后2、3、6、9周分别杀死动物作光镜及电镜观察。结果在电镜下发现有三类细胞,即成骨系、破基质系细胞和血管内皮细胞,并见到非成骨性结缔组织的间充质细胞分化为前成骨细胞→成骨细胞→骨细胞以及其同时分化为血管内皮细胞的全部过程。表实验从组织学和细胞学二方面证实DGB确有诱导成骨的作用。     

脂肪因子Chemerin对骨代谢影响的研究进展

现代社会肥胖人群逐年增多,肥胖相关代谢性骨病的患者也日益增多,严重危害人群健康。Chemerin作为一种脂肪因子,主要由脂肪细胞和肝细胞分泌,在循环中水平高于经典脂肪因子如Leptin和Adiponectin,对全身代谢和免疫发挥重要作用。近年研究发现,肥胖状态下伴随着外周脂肪组织的增多,骨髓内脂肪组织也急剧增加。骨髓内脂肪细胞分泌Chemerin,通过旁分泌或自分泌方式抑制成骨细胞分化和促进破骨细胞分化以及影响骨髓腔微环境。本文将系统回顾国内外有关Chemerin与骨代谢相关研究的文献,并探讨Chemerin对骨代谢的影响及其机制。     

人脐血间质干细胞条件培养基在受损成骨细胞中的作用与机制

目的探讨线粒体活性在人脐带间充质干细胞(human umbilical cord mesenchymal stem cells,HUMSCs)条件培养基修复受损成骨细胞中的作用及其机制。方法提取、培养HUMSCs及制作其条件培养基,建立成骨细胞氧化损伤模型。实验分组:无血清DMEM培养基组、晚期氧化蛋白(advanced oxidation protein products,AOPPs)刺激组、常规培养基组、条件培养基组,培养1 h后用流式细胞仪以及Mito Tracker Red分析成骨细胞凋亡率、线粒体活性,并用蛋白-凝胶成像法(western-blot,WB)分析Caspase-3凋亡蛋白表达差异,从而评价HUMSCs条件培养基对遭受氧化损伤的成骨细胞的保护、修复、逆转作用,以及线粒体在其中发挥的作用及其机制。结果HUMSCs条件培养基可以增加氧化应激作用下成骨细胞内线粒体活性;HUMSCs条件培养基可降低成骨细胞凋亡率,减少Caspase-3凋亡蛋白表达。结论HUMSCs条件培养基通过缓解氧化应激(oxidative stress,OS)导致的线粒体功能与结构损伤,并下调Caspase-3凋亡蛋白的表达,抑制OB凋亡。     

丹参对人成骨细胞缺血-再灌注损伤的保护作用

观察丹参对成骨细胞缺血－再灌注损伤的保护作用。方法：以人髂骨骨膜为材料进行成骨细胞的体外培养,经丹参预处理后,行模拟缺血－再灌注采用唑蓝比色法测定细胞的夏活率。结果：预处理组成骨细胞的存活率明显高于对照组。结论：丹参对人成骨细胞缺血－再灌注有明显的保护作用。