The Effect of Cyclic Stretching on Matrix Production, Mineralization and Differentiation of Osteoblasts

A four-point bending apparatus is used to investigate the effects of stretching on collagen synthesis, mineralization and differentiation of osteoblasts. Cells are stretched at 1500με for 24 hours. The responses of osteoblasts to mechanical signal of physiological stretching are evaluatedfrom three aspects: collagen production, extracellular inorganic calcium secretion and ALP activity. The results show that osteoblasts decrease the collagen synthesis, calcium secretion and ALP activity compared to the control cells (65.82 %, 73.51%, 48.10 96 respectively ), confirming that cyclic stretching at 1500με inhabits the ohvsiological activity of osteoblasts.     

La3+通过重组细胞骨架影响大鼠成骨细胞增殖、分化

研究了稀土离子La3 对体外培养的成骨细胞增殖、分化及细胞骨架的影响,并初步探讨了相关机理.用细胞计数法检测了成骨细胞的增殖.用RT-PCR技术测定了碱性磷酸酶(ALP)、骨钙素(OC)、骨桥蛋白(OPN),骨涎蛋白(BSP)以及cbfa-1 mRNA水平.采用激光扫描共聚焦显微镜观察了细胞中F肌动蛋白(F-actin)的变化.结果显示:La3 在48h促进了成骨细胞增殖;在4 d促进了早期分化指标ALP,BSP和cbfa-1 mRNA的表达;在21d促进了晚期分化指标OC和OPN mRNA的表达.与此同时,La3 使成骨细胞骨架发生重组.另外,Western Blot分析证实La3 作用于成骨细胞短时间即可激活粘着斑激酶(FAK)酪氨酸磷酸化.结果提示,La3 通过提高FAK酪氨酸的磷酸化水平,改变细胞骨架的分布和聚合,从而促进成骨细胞的增殖和分化.     

Ⅰ型骨质疏松山羊骨髓基质细胞体外成脂、成骨分化的研究

观察体外定向诱导Ⅰ型骨质疏松山羊骨髓基质细胞（BMSCs）分化为脂肪细胞和成骨细胞.建立去卵巢骨质疏松山羊动物模型,全骨髓法分离培养其骨髓基质细胞.第二代细胞分别成脂、成骨诱导培养,油红O染色、碱性磷酸酶染色、茜素红染色判定其分化结果.成脂诱导21 d,油红O染色有脂滴形成;成骨诱导14 d,碱性磷酸酶染色阳性;连续诱导35 d,茜素红染色证实有钙化结节形成.Ⅰ型骨质疏松山羊骨髓基质细胞在体外可以定向诱导分化为脂肪细胞和成骨细胞.     

成骨细胞对周期性拉伸刺激的生理响应和胞内Ca2+浓度变化

骨组织的生长发育受到力学因素的调控. 对大鼠颅盖骨中分离出的成骨细胞施加周期性拉伸刺激, 结果表明500微应变的加载明显促进了细胞的增殖, 而1000和1500微应变的拉伸抑制了细胞的增殖. 各应变水平的拉伸增加了细胞与基底间的黏附力和细胞的铺展面积. 用荧光探针Fluo-3/AM测定拉伸对成骨细胞胞内Ca2+浓度的影响, 发现在500微应变下拉伸5 min后成骨细胞胞内Ca2+浓度比对照组有明显增加. 用三七总皂苷阻断胞内Ca2+通道后, 成骨细胞对应变的响应仍表现出胞内Ca2+浓度的升高; 但与未加三七总皂苷的加载组相比, 胞内Ca2+浓度响应应变后的升高由原来的92.9%的增加降低到28.6%的增加. 说明在成骨细胞响应周期性拉伸应变的过程中胞内Ca2+ 浓度的升高既有胞外钙内流的参与, 也有胞内钙库的释放作用, 其中胞外钙通过跨膜通道的内流起主要作用.     

脂肪干细胞探源

所谓脂肪干细胞,即为脂肪组织所含有的多能性干细胞。脂肪组织,传统观念一般认为是一个简单、被动贮存脂质、能量的场所,最主要的功能是能量调控作用,但最近研究发现,脂肪组织可分泌多种激素样物质,对机体内分泌环境具有调节作用,尤其在炎症反应和免疫应对方面,因此已被认为是一个内分泌器官。在胚胎发育过程中,脂肪组织和骨髓都是来源于中胚层,最初人们通过提取骨髓组织研究分离出具有多向分化能     

rhIGF-I对大鼠骨质疏松性骨折愈合过程中OPG表达的影响

目的：观察骨质疏松性骨折愈合不同阶段骨保护素（osteoprotegerin，OPG）的表达，探讨胰岛素生长因子-Ⅰ（recombinant human insulin-like growth factor，rhIGF-1）对该过程OPG表达的影响。方法：6月龄雌性大鼠40只，制备右股骨骨质疏松性骨折模型后，随机分为IGF治疗组及生理盐水对照组，并分别于术后第10、20、30、40d取骨痂，通过RT-PCR及ELISA检测各组骨痂OPG表达。结果：在大鼠骨质疏松性骨折愈合过程中成骨细胞活性降低，OPG表达呈弱阳性表达，骨折愈合缓慢；rhIGF-1局部注射治疗能增加骨痂中OPG的表达量（P〈0．05），促进骨质疏松性骨折愈合。结论：OPG是rhIGF-促骨质疏松性骨折愈合的重要下调因子。     

日本：依托民生科技 实现强国梦想

2011年7月27日，日本名古屋大学医院发布公告说，该医院开发出一种新技术，可通过移植骨髓细胞，治疗因骨骼疾病而患低身高症的患者。该技术需要首先从患者的骨髓液中采集骨髓细胞进行培养，使其分化为能够制造骨骼的成骨细胞，然后将成骨细胞注入腿骨之间的缝隙，促进骨骼形成。这项技术完善和应用将为低身高症的患者带来福音，这也是科技对人类疾病的一场胜利。近年来，日本把解决民生问题作为政府制定科技政策或设立科研项目的重要导向，     

Alternative splicing and expression of the insulin-like growth factor （IGF-1） gene in osteoblasts under mechanical stretch

Insulin-like growth factor 1 (IGF-1) promotes osteoblasts differentiation and bone formation, and its expression is induced by mechanical stretch, thus IGF-1 has been considered an effector molecule that links mechanical stimulation and local tissue responses. In this study, a mechanical stretching device was designed to apply physiological level static or cyclic stretching stimulation to osteoblasts. Different isoforms of IGF-1 mRNA were amplified by RT-PCR from the cells using respective primers and these amplified products were sequenced. An iso-form of IGF-1 splicing product was found to be selectively produced by osteoblasts under stretching stimulation. This IGF-1 isoform had identical sequence with the mechano growth factor (MGF) which was originally identified in muscle cells. Regulations of the expression of the liver-type IGF (L.IGF-1) and MGF in osteoblasts under stretch stimulation were further studied using semi-quantitative RT-PCR. Stretch stimulation was found to promot the expression of IGF-1 (L.IGF-1 and MGF), and for both isoforms expression was more effectively stimulated by cyclic stretch than static stretch. MGF was detected only in osteoblasts subjected to mechanical stretch, suggesting MGF was a stretch sensitive growth factor. Expression of MGF peaked earlier than that of L.IGF-1, which was similar to their regulation in muscle and suggested similar roles of MGF and L.IGF-1 in bone as in muscle cells. The functions of MGF and LIGF-1 in osteoblasts shall be established by further experimental studies.     

成骨细胞钙响应在稳恒、脉冲流体中的实时检测和研究

We investigated the intercellular calcium ([Ca²⁺]_i) responses in rat osteoblasts resulted fromboth steady and pulsed fluidic shear stress (F_ss) based on our design microfluidic device, by altering F_ssintensity, F_ss stimulation time (width) and interval time. Results showed that steady F_ss obviously induced[Ca²⁺]_i responses with two distinct phases: a peak phase and a plateau phase. The peak phase was sensitiveto the F_ss intensity, while plateau phase was dependent on application of F_ss width. Meanwhile, a reductivetendency of [Ca²⁺]_i responses was observed as experienced by different repetitive pulsed F_ss . This reductivetendency of [Ca²⁺]_i was alleviated with increment of interval time.     

Ι型骨质疏松山羊骨髓基质细胞体外成脂、成骨分化的研究

观察体外定向诱导Ι型骨质疏松山羊骨髓基质细胞(BMSCs)分化为脂肪细胞和成骨细胞。建立去卵巢骨质疏松山羊动物模型,全骨髓法分离培养其骨髓基质细胞。第二代细胞分别成脂、成骨诱导培养,油红O染色、碱性磷酸酶染色、茜素红染色判定其分化结果。成脂诱导21d,油红O染色有脂滴形成;成骨诱导14d,碱性磷酸酶染色阳性;连续诱导35d,茜素红染色证实有钙化结节形成。Ι型骨质疏松山羊骨髓基质细胞在体外可以定向诱导分化为脂肪细胞和成骨细胞。