静磁场作用下金属离子对成骨细胞的毒性

背景：体内体外实验研究证明,静磁场具有促进成骨细胞分化及骨形成的作用。 目的：观察静磁场作用下金属离子对成骨细胞毒性的影响。 方法：将CoCl₂粉末与CrCl₃粉末溶于无菌注射用水配制成CoCl₂溶液和CrCl₃溶液,将金属离子Co²⁺、Cr³⁺分别与小鼠颅骨成骨细胞(MC3T3-E1)在不同的磁场强度(1,10,100 mT)下共培养。实验分4组：设Co²⁺+Cr³⁺组(对照组)和Co²⁺+Cr³⁺组分别+1,10,100 mT组。 结果与结论：恒磁场作用下的成骨细胞呈现更加成熟的形态学特征,Co²⁺、Cr³⁺金属离子对成骨细胞MC3T3的毒性明显降低;同时G2M(分裂期)分布比例明显增加,细胞停滞在G0G1(休眠期)的比率明显减少;与对照组相比,不同场强磁场加载后,成骨细胞碱性磷酸酶活性明显增强(P < 0.05)。提示一定强度的静磁场可拮抗Co²⁺、Cr³⁺金属离子对成骨细胞的毒性作用。     

周期性牵张力对成骨细胞细胞骨架影响的实验研究

目的 对大鼠成骨细胞施加单轴向周期性牵张应力,观察单轴向周期性牵张应力对大鼠成骨细胞细胞骨架的影响.方法 无菌环境下,组织分离法培养SD大鼠颅骨成骨细胞,体外培养,应用DioDynamic细胞应力加载系统分别对2组第3代大鼠成骨细胞加载0%和2%的单轴向周期性牵张应力,使用免疫荧光法检测细胞骨架蛋白表达,使用激光共聚焦显微镜观察细胞骨架的变化,随即抽取视野并测量各组细胞骨架蛋白表达的荧光强度,进行统计学分析.结果 经统计学计算,施加单轴向周期性牵张应力实验组与空白对照组相比,实验组大鼠成骨细胞骨架蛋白的荧光表达减弱;应力纤维变细,明显沿受力方向分布.结论 DioDynamic细胞应力加载系统可以很好地模拟生物体内成骨细胞所受单向周期牵张应力;大鼠成骨细胞细胞骨架感知单轴向周期性牵张应力,参与细胞的力学信号转导和细胞形态重构.     

电磁场对骨组织和成骨细胞的作用

电学环境是骨组织所处的重要微环境之一，外加电磁场对骨组织和成骨细胞有重要作用。临床上电磁场已被用于治疗骨折、骨不连、骨质疏松等骨科病症，并已取得满意的效果。本综述了电磁场对骨组织和成骨细胞的影响及机理，并对电磁场对骨组织工程化培养的意义进行了探索。     

电磁场对骨组织和成骨细胞的作用

电学环境是骨组织所处的重要微环境之一 ,外加电磁场对骨组织和成骨细胞有重要作用。临床上电磁场已被用于治疗骨折、骨不连、骨质疏松等骨科病症 ,并已取得满意的效果。本文综述了电磁场对骨组织和成骨细胞的影响及机理 ,并对电磁场对骨组织工程化培养的意义进行了探索     

旋转磁场及静磁场对人肝癌细胞增殖的影响

目的：利用旋转磁场和静磁场对人肝癌细胞进行作用，探讨磁场对人肝癌细胞增殖的影响。材料和方法：将细胞株HepG2接种于96孔培养板，在37℃、5%CO2恒温培养箱培养24小时后放置于0．2T的旋转磁场（0－10Hz频率可调）和0．2T的静磁场中，作用一定时间后利用MTT法检测细胞增殖情况。结果：短时的旋转磁场作用和长时的静磁作用对HepG2细胞株的增殖无明显影响。     

机械刺激对成骨细胞骨架的影响

机械刺激在骨组织的正常代谢和重建过程中起着十分重要的作用。机械刺激作用于骨组织后可以通过包括成骨细胞在内的多种应力感受细胞,感知并传导力学信号。细胞骨架作为贯穿细胞整体的纤维网状支架结构,与细胞外基质及整合素构成一个整体,是力学信号传递的关键环节之一。力学刺激可引起骨架纤维重排并可借助第二信使将力学信号传递并转换,最终调节基因的表达。该信号通路涉及的分子主要包括Rho家族、蛋白激酶C以及黏附斑激酶。本文将就近几年关于机械刺激下成骨细胞骨架的改变及作用机制的研究进展进行综述。     

三种波形磁场对大鼠成骨细胞增殖与分化的影响

目的：研究不同波形磁场辐照，对离体大鼠成骨细胞增殖与分化的影响。方法：用矩形、三角形和正弦三种典型波形磁场辐照离体成骨细胞。结果：频率15Hz，幅值5mT，矩形磁场促进细胞增殖（P〈0．01），抑制细胞分化（P〈0．01）;正弦磁场抑制细胞增殖（P〈0．01），促进细胞分化（P〈0．01）；三角彤磁场对细胞增殖和分化的影响尤显著性差异．结论：除强度和频率窗外，还需考虑波形的影响。     

一定强度静磁场可促进许旺细胞快速分泌神经生长因子

背景：国内外对静磁场加载许旺细胞的研究较少,对其产生的生物学效应尚不清楚。目的：探索静磁场对许旺细胞分泌神经生长因子水平的影响。方法：将传代良好的许旺细胞随机分为3组,分别为0.05 mT静磁场组、0.1 mT静磁场组、空白对照组。从接种第2天即开始静磁场加载,每天曝磁12 h,空白对照组不进行静磁场加载。加载6 d后利用RT-PCR技术检测许旺细胞中神经生长因子mRNA的表达,ELISA技术检测许旺细胞分泌神经生长因子水平。结果与结论：静磁场组培养上清中神经生长因子mRNA的表达和分泌神经生长因子水平显著高于空白对照组(P < 0.05);0.1 mT静磁场组神经生长因子mRNA的表达和分泌神经生长因子水平虽高于0.05 mT静磁场组,但是差异无显著性意义(P >0.05)。结果表明一定强度的静磁场可以促进许旺细胞快速分泌神经生长因子。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

纳米生物材料及其表面对成骨细胞生物学行为影响的研究进展

骨组织工程是再生医学的重要组成部分,支架材料和种子细胞是其关键。近年来,随着纳米技术等相关学科的发展,在骨组织工程领域,研究人员对成骨细胞株的选择和培养、纳米材料的元素组成、表面形态、表面粗糙度及表面改性等方面进行了大量研究,并在纳米材料对成骨细胞生物学行为的影响方面取得了重要的研究成果和进展,本文对近年来在该领域内的研究进展作一综述。     

静磁场对大鼠牙周膜中P物质影响的实验研究

目的　研究静磁场作用下大鼠牙周膜中SP的作用。方法　用免疫组织化学方法和显微图像分析对大鼠牙周膜中的SP进行不同时相的定位及定量研究。结果　在静磁场作用下大鼠牙周膜中SP呈现时间变化性 ,2小时SP纤维密度达峰值。结论　静磁场可使牙周膜中SP阳性纤维密度显著增加     

恒定磁场中大鼠成骨细胞的增殖和功能活性

背景：磁场对成骨细胞生物学的影响存在一定的分歧。 目的：探讨不同强度恒定磁场作用不同时间后成骨细胞增殖和功能活性的改变。 方法：用体外培养的SD大鼠成骨细胞第3~5代分别在0,5,22,86,135 mT恒定磁场下培养,观察8,12,24 h后细胞增殖和凋亡变化及细胞上清液中骨钙素及Ⅰ型前胶原C端前肽的表达。 结果与结论：磁场作用8,12 h后,5,22,86,135 mT磁场培养的细胞增殖指数均高于对照组(P < 0.05),作用24 h时,仅5 mT组高于对照组(P < 0.05)。而0,5,22,86,135 mT恒定磁场下培养8,12,24 h的凋亡百分数差异无显著性意义。磁场作用8 h后,22,86,135 mT组骨钙素分泌量均高于对照组(P < 0.05);作用24 h后,135 mT组骨钙素分泌量则明显低于对照组(P < 0.05);而磁场作用8,12 h后,22,86 mT组Ⅰ型前胶原C端前肽分泌量明显高于对照组(P < 0.05),作用24 h后,135 mT组Ⅰ型前胶原C端前肽分泌量则明显低于对照组(P < 0.05)。表明低强度磁场、短时间作用可促进成骨细胞的增殖及成骨物质的分泌,而高强度磁场或磁场暴露时间过长则抑制成骨细胞增殖及成骨物质的分泌。     

Effect of a static magnetic field on the growth rate andin vitro angiogenesis of endothelial cells

It is shown that a static magnetic field accelerates the growth rate of endothelial cells from the bovine pulmonary artery, but has no effect on the attachment and growth of cells from the human umbilical vein. A static magnetic field markedly stimulates the differentiation of endotheliocytes from the human umbilical vein to capillary-like structures. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 1, pp. 106–108, January, 1994 Presented by V. N. Smirnov, Member of the Russian Academy of Medical Sciences     

Behavioral effects on rats of motion within a high static magnetic field

Some human subjects report vestibular disturbances such as vertigo, apparent motion, and nausea around or within high strength MRI systems operating at 4 T to 9.4 T. These vestibular effects have been ascribed to the consequences of movement through the high magnetic field. We have previously found that exposure to magnetic fields above 7 T suppresses rearing, causes locomotor circling, and induces conditioned taste aversion (CTA) in rodents. The present experiments were designed to test the effects on rats of motion through the magnetic field of the 14.1 T superconducting magnet. In Experiment 1, we compared the effects of multiple rapid insertions and removals from the center of the magnet to the effects of continuous exposure. Repeated traversal of the magnetic field gradient with only momentary exposure to 14.1 T was sufficient to suppress rearing and induce a significant CTA. Repeated insertion and removal from the magnet, however, did not have a greater effect than a single 30-min exposure on either acute locomotor behavior or CTA acquisition. Prolonged exposure was required to induce locomotor circling. In the second series of experiments, we controlled the rate of insertion and removal by means of an electric motor. Locomotor circling appeared to be dependent on the speed of insertion and removal, but the suppression of rearing and the acquisition of CTA were independent of speed of insertion and removal. In Experiment 3, we inserted rats into the center of the magnet and then rotated them about their rostral-caudal axis during a 30-min 14.1 T exposure. Rotation within the magnet did not modulate the behavioral effects of exposure. We conclude that, in rats, movement through the steep gradient of a high magnetic field has some behavioral effects, but sustained exposure to the homogenous center of the field is required for the full behavioral consequences.     

Effects of micrometric titanium particles on osteoblast attachment and cytoskeleton architecture

Titanium (Ti) and its alloys are widely used in biomedical devices as bone tissue replacements due to their advantageous bulk mechanical properties and biocompatibility. It is known that particles released from Ti-based implants impair essential functions of osteoblasts, which for survival require attachment to specific extracellular matrix proteins at the bone surface. This study investigates whether Ti particles of micrometric sizes affect the osteoblast attachment machinery. Exposure of human osteoblastic Saos-2 cells to Ti particles impaired their adhesion strength, migration and proliferation. Attenuation of these functions was associated with reduced cell spreading, cell membrane disruptions and loss of cell shape. Cell exposure to Ti particles led to changes in cytoskeletal structures, including reduced ventral stress fibers combined with a disorderly arrangement of β-tubulin and acetylated α-tubulin fibers. Cytoskeleton disassembly was associated with a reduction in overall cell adhesion area, characterized by fewer centrally localized focal adhesions and shorter focal contacts at the periphery. Paxillin adaptor protein redistributed to peripheral corner regions, colocalizing with poorly organized actin fibers at attachment sites. Total focal adhesion kinase (FAK) protein amounts, as well as its degree of phosphorylation on the active form p-FAK (Tyr-397), decreased, which was accompanied by a lesser extent of co-localization with paxillin in focal contacts. On the other hand, p-FAK (Tyr-407), an inhibitory form of FAK, accumulated in the focal contacts of Ti-treated cells. Pyk2 phosphorylated on Tyr-402 colocalized with paxillin in focal contacts of untreated cells, while it was barely detected upon exposure to particles. In summary, changes in the phosphorylation states of both FAK and Pyk2 tyrosine kinases at focal contacts underlie impaired bone-forming cell attachment after exposure to Ti particles of micrometric sizes.     

Effect of hypogeomagnetic field on tissue and intracellular reorganization of mouse myocardium

Structural reorganization of the myocardium is observed in CBA mice under conditions of hypogeomagnetic field (reduction by 10⁵ times). Changes in tissue architectonics manifest themselves in a reduced capillary/cardiomyocyte volume ratio against the background of hemodynamic disturbances. Intracellular disturbances result from impaired regeneration processes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 10, pp. 455–459, October, 1997     

稳恒磁场对体外胚胎中脑神经元细胞分化影响的研究

本文利用大鼠胚胎中脑神经细胞作原代微团培养，培养物经不同强度（分别为５ ｍ Ｔ，１０ ｍ Ｔ，２０ｍ Ｔ，３０ ｍ Ｔ，４０ ｍ Ｔ，５０ ｍ Ｔ和６０ ｍ Ｔ）的稳恒磁场作用，研究其对细胞生长和分化的影响，并利用图像分析细胞形态的变化。结果表明：各种强度的稳恒磁场能明显地抑制中脑神经细胞的分化，集落形成率明显减少，且细胞表面的突起和集落间的神经纤维束减少。     

恒定磁场协同阿霉素诱导肝癌细胞凋亡的研究

目的：探讨恒定磁场联合阿霉素对诱导肝癌细胞凋亡的影响。方法：采用流式细胞仪碘化丙啶染色法和活细胞荧光染色法（Ｈｏｅｃｈｓｔ染色法），观察不同处理因素对细胞凋亡率的影响。结果：两种实验方法均显示０５ｍｇ／Ｌ的阿霉素与对照组比较没有显著差异（Ｐ＞００５），而单独用恒定磁场或１０ｍｇ／Ｌ的阿霉素与对照组比较有显著性差异（Ｐ＜００５）。应用恒定磁场后发现，０５ｍｇ／Ｌ和１０ｍｇ／Ｌ浓度的阿霉素诱导ＨｅｐＧ－２细胞凋亡的结果与对照组相比，均有显著差异（Ｐ＜００５）。结论：恒定磁场具有增强阿霉素诱导肝癌细胞凋亡的作用     

Suppression of drinking by exposure to a high-strength static magnetic field

High-strength static magnetic fields of 7 T and above have been shown to have both immediate and delayed effects on rodents, such as the induction of locomotor circling and the acquisition of conditioned taste aversions. In this study, the acute effects of magnet field exposure on drinking were examined. Exposure to a 14.1-T magnetic field for as little as 5 min significantly decreased the amount of a glucose and saccharin solution (G+S) consumed by water-deprived rats over 10 min. The decreased intake could be accounted for largely, but not entirely, by an increase in the latency of magnet-exposed rats to initiate drinking. When intake was measured for 10-60 min after the initiation of drinking, thus controlling for increased latency, magnet-exposed rats still consumed less G+S than sham-exposed rats. The increased latency was not due simply to an inability of magnet-exposed rats to reach the elevated sipper tube of the G+S bottle, providing rats with long tubes that could be reached without raising their heads normalized intake but latency was still increased. The increased latency and decreased intake appeared to be secondary to somatic effects of magnet exposure, however, because during intraoral infusions magnet-exposed rats consumed the same amount of G+S with the same latency to reject as sham-exposed rats. The suppression of drinking by magnetic field exposure is consistent with the acute effects of other aversive stimuli, such as whole-body rotation, on short-term ingestion. These results add to the evidence that high-static strength magnetic fields can have behavioral effects on rodents.     

Cell response induced by internalized bacterial magnetic nanoparticles under an external static magnetic field

Magnetic nanoparticles are widely used in bioapplications such as imaging and targeting tool. Their magnetic nature allows for the more efficient bioapplications by an external field gradient. However their combined effects have not yet been extensively characterized. Herein, we first demonstrate the biological effects of the communications between internalized bacterial magnetic nanoparticles (BMPs) and an external static magnetic field (SMF) on a standard human cell line. Combination of the BMPs and SMF act as the key factor leading to the alteration of cell structure and the enhanced cell growth. Also, their interaction reduced the apoptotic efficiency of human tumor cells induced by anticancer drugs. Microarray analysis suggests that these phenomena were caused by the alterations of GPCRs-mediated signal transduction originated in the interaction of internalized BMPs and the external SMF. Our findings may offer new approach for targeted cell therapy with the advantage of controlling cell viability by magnetic stimulation.