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。     

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。     

成骨细胞的数量对体外钙化结节形成的影响

随着成骨细胞体外培养技术的发展,其体外培养已成为骨组织工程及骨替代材料研究的一个重要手段.成骨细胞的体外钙化是体外培养成骨细胞的一个重要生物学特征,对成骨细胞的鉴定、与材料的相容性及其材料的生物学效应的研究尤为重要.成骨细胞的接种浓度对其体外钙化有一定的影响,国内外文献未见关于这方面的报道.成骨细胞体外钙化形成条件的研究可望为骨替代材料的研究提供参考.     

骨细胞间隙连接与物理-生物信号传导研究进展

物理信号特别是力负载在骨转换中起重要作用,而骨组织中的细胞成分是对其周围环境的刺激作出反应的基本结构单位,它们在接受刺激后通过结构和功能的调整从而作出反应.然而力负载通过什么途径对细胞群体产生作用,骨细胞对力负载引起的顺式反应机理至今还令人困惑.本文综合近年来一些最新实验研究,阐述骨细胞间隙连接(gap junction)在组成骨细胞网络,并通过间隙连接的细胞内通讯(GJIC)机制在力学传递中的重要作用,其中对间隙连接的结构、功能,力负载(如应力、底物变形、流体流动、电磁场等)引起的生物物理信号在GJIC的传递,GJIC对成骨细胞分化的调节等方面作了综述,并提出GJIC的进一步研究与组织工程关系的启示.     

极低频三角形电磁场对成骨细胞的影响

目的:观察三角形极低频电磁场对新生大鼠颅盖骨成骨细胞增殖与分化的影响.方法:采用频率为15Hz、不同强度、不同形状的三角形电磁场作用于成骨细胞,测量成骨细胞的增殖与碱性磷酸酶活性(ALP).结果:频率为15 Hz, 强度为4 mT～5 mT,三角形电磁场能够显著提高成骨细胞的增殖率和ALP的活性,而强度为8 mT时则显著抑制成骨细胞的增殖与ALP的活性;不同形状的三角形电磁场也明显影响成骨细胞的功能,其中以p为38%、85%对成骨细胞的影响最为明显.结论:电磁场的生物学效应依赖于其参数特征.     

骨细胞间隙连接与物理—生物信号传导研究进展

物理信号特别是力负载在骨转换中起重要作用，而骨组织中的细胞成分是对其周围环境的刺激作出反应的基本结构单位，它们在接受刺激后通过结构和功能的调整从而作出反应。然而力负载通过什么途径对细胞群体产生作用，骨细胞对力负载引起的顺式反应机理至今还令人困惑。本综合近年来一些最新实验研究，阐述骨细胞间隙连接(gap junction)在组成骨细胞网络，并通过间隙连接的细胞内通讯(GJIC)机制在力学传递中的重要作用，其中对间隙连接的结构、功能，力负载(如应力、底物变形、流体流动、电磁场等)引起的生物物理信号在GJIC的传递，GJIC对成骨细胞分化的调节等方面作了综述，并提出GJIC的进一步研究与组织工程关系的启示。     

脉冲电磁场对体外培养成骨细胞的影响

脉冲电磁场影响体外培养的成骨样细胞,促使其增殖、分化、并加速骨样组织形成,对成骨细胞形态学上也有一定影响,本文综述近年来国内外在电磁场对成骨细胞作用方面的一些研究进展.     

不同占空比低强度脉冲电磁场对大鼠成骨细胞的影响

目的：研究磁感应强度为1mT、频率为15Hz不同占空比的脉冲电磁场（pulsedelectromagneticfields,PEMFs）对体外培养大鼠成骨细胞增殖与细胞分化的影响。方法：取新生SD大鼠仔鼠头盖骨,用骨组织块培养法分离成骨细胞,培养至第3代后,分另q对其进行场强1mT、频率15Hz,占空比10％、20％、40％、60％的脉冲电磁场作用,8h／d,持续作用3d．应用MTT法、碱性磷酸酶测定检测成骨细胞增殖、分化情况。结果：不同占空比PEMFs对大鼠成骨细胞增殖与分化影响程度不同,20％、40％和60％占空比组显著提高成骨细胞增殖水平（P〈0．05）,其中40％和60％占空比组作用效果最显著（P〈0．01）。10％、20％、40％和60％占空比组均能促进成骨细胞分化（P〈0．05）,其中以60％占空比组的效果最为明显fP〈O．01）。结论：本研究进一步证实了低强度PEMFs能够促进成骨细胞的增殖与分化,并且PEMFs对成骨细胞的影响依赖于占空比参数的选择．而且有可能存在“占空比”窗口。     

骨组织工程应用可降解聚合物的可能性探讨

成骨细胞细胞外基质材料的选择是骨组织工程研究中一项重要而紧迫的任务。本文阐述了理想骨组织工程基质材料的研制要求 ,介绍了几种可降解聚合物在骨组织工程中的应用现状 ,并重点介绍了 PL A、PGA及其共聚物的优缺点和相应的改进方法。作者认为 ,以合成可降解聚合物为主要组成成分的新型基质材料必将在未来骨组织工程研究中展示出可喜的应用前景     

力学刺激对成骨细胞作用机制的研究进展

力学环境在维持骨组织正常形态和功能活动中发挥着重要的影响,目前研究采用的细胞生物力学装置模拟了压应力、张应力及流体剪切力等不同应力模式对培养中细胞的作用.并发现成骨细胞对不同类型的力学刺激有不同的感受和应答机制,甲状旁腺素、应力的频率、大小等也影响着力学刺激对成骨细胞的作用效应.     

Polymeric Scaffolds for Bone Tissue Engineering

Bone tissue engineering is a rapidly developing area. Engineering bone typically uses an artificial extracellular matrix (scaffold), osteoblasts or cells that can become osteoblasts, and regulating factors that promote cell attachment, differentiation, and mineralized bone formation. Among them, highly porous scaffolds play a critical role in cell seeding, proliferation, and new 3D-tissue formation. A variety of biodegradable polymer materials and scaffolding fabrication techniques for bone tissue engineering have been investigated over the past decade. This article reviews the polymer materials, scaffold design, and fabrication methods for bone tissue engineering. Advantages and limitations of these materials and methods are analyzed. Various architectural parameters of scaffolds important for bone tissue engineering (e.g. porosity, pore size, interconnectivity, and pore-wall microstructures) are discussed. Surface modification of scaffolds is also discussed based on the significant effect of surface chemistry on cells adhesion and function.     

Pulsed electromagnetic fields accelerate apoptotic rate in osteoclasts

Selective control of cell function by applying specifically configured, low-energy, time-varying electromagnetic fields (EMF) has added a new, exciting dimension to biology and medicine. However, the mechanism involved is less clear. In our study, we investigated the effect of pulsed electromagnetic fields (PEMF) on induction of osteoclasts apoptosis. A statistically significant increase of apoptotic rate in osteoclasts (48 hr after isolation) was found when exposed to 7.5 Hz PEMF with induced electric fields intensity of 3.0 muv/cm for 8 (105%, p < 0.001) and 16 hr (30%, p < 0.05). However, exposure of osteoclasts to PEMF for only 1 hr showed no statistically significant differences. These findings suggest that PEMF have the ability to speed up apoptosis of osteoclasts derived from primary osteoblasts and bone marrow cells cocultures. This in vitro study, therefore, could be considered as groundwork for in vivo PEMF applications on some osteoclasts-associated bone diseases such as osteoporosis.     

Pulsed Electromagnetic Fields Accelerate Apoptotic Rate in Osteoclasts

Selective control of cell function by applying specifically configured, low-energy, time-varying electromagnetic fields (EMF) has added a new, exciting dimension to biology and medicine. However, the mechanism involved is less clear. In our study, we investigated the effect of pulsed electromagnetic fields (PEMF) on induction of osteoclasts apoptosis. A statistically significant increase of apoptotic rate in osteoclasts (48 hr after isolation) was found when exposed to 7.5 Hz PEMF with induced electric fields intensity of 3.0 μv/cm for 8 (105%, p < 0.001) and 16 hr (30%, p < 0.05). However, exposure of osteoclasts to PEMF for only 1 hr showed no statistically significant differences. These findings suggest that PEMF have the ability to speed up apoptosis of osteoclasts derived from primary osteoblasts and bone marrow cells cocultures. This in vitro study, therefore, could be considered as groundwork for in vivo PEMF applications on some osteoclasts-associated bone diseases such as osteoporosis.     

Biomimetic PMMA-based bone substitutes: a comparative in vitro evaluation of the effects of pulsed electromagnetic field exposure

Pulsed electromagnetic fields (PEMFs) are known to be effective in the stimulation of cultured osteoblasts and in vivo healing of delayed and nonunion fractures. In the present in vitro study the effects of PEMFs on osteoblastic cell cultures (MG63 human osteoblast-like cells) grown in the presence of poly-methylmethacrylate (PMMA) and of a biomimetic bone substitute made of a PMMA matrix added with alfa-tricalcium phosphate (PMMA+alpha-TCP) were evaluated, to assess the biological response at the cell-biomaterial interaction. Cultures were stimulated with PEMFs (75 Hz, 2.3 mT, 1.3-ms pulse duration) 12 h/day for 3 days and evaluations (MTT, ALP, OC, PICP, TGFbeta-1, IL-6) were performed at 3 and 6 days. PMMA had a negative effect on osteoblasts, whereas PMMA+alpha-TCP enhanced production of ALP, PICP, OC and TGFbeta-1, and reduced IL-6 levels. Cells responded positively to PEMF stimulation even when cultured with a poorly biocompatible material, such as PMMA. This effect was more evident in the presence of PMMA+alpha-TCP (further improvement in proliferation and synthetic activity) both at 3 and at 6 days. The properties of PMMA+alpha-TCP look promising, and the present results support the use of PEMFs to improve tissue response to biomaterials implanted as bone substitutes.     

极低频脉冲电磁场对新生大鼠成骨细胞的影响

目的：观察极低频脉冲电磁场（pulsed electromagnetic fields，PEMF）对体外培养成骨细胞增殖、分化、体外矿化的影响。方法：采用频率为15Hz、强度为5mT、占空比为15％的PEMF作用于成骨细胞，检测成骨细胞的增殖、碱性磷酸酶（alkaline phosphatase，ALP）活性以及体外矿化指标。结果与结论：PEMF显著促进成骨细胞增殖和体外矿化，抑制ALP活性作用。     

Surface modification of a porous polyurethane through a culture of human osteoblasts and an electromagnetic bioreactor.

There is increasing interest in new biomaterials and new culture methods for bone tissue engineering, in order to produce, in vitro, living constructs able to integrate in the surrounding tissue. Using an electromagnetic bioreactor (magnetic field intensity, 2 mT; frequency, 75 Hz), we investigated the effects of electromagnetic stimulation on SAOS-2 human osteoblasts seeded onto a porous polyurethane. In comparison with control conditions, the electromagnetic stimulation caused higher cell proliferation, increased surface coating with decorin and type-I collagen, and higher calcium deposition. The immunolocalization of decorin and type-I collagen showed their colocalization in the cell-rich areas. The use of an electromagnetic bioreactor aimed at obtaining the surface modification of the porous polyurethane in terms of cell colonization and coating with calcified matrix. The superficially modified biomaterial could be used, in clinical applications, as an implant for bone repair.     

成骨细胞与纳米植入材料相互作用研究进展

骨植入材料与周围骨组织的骨整合对于材料的稳定性有着巨大影响,其中成骨细胞产生各种不同的蛋白质分子完成胞体与材料以及周围细胞的连接.这些蛋白质分子包括细胞外基质蛋白、细胞骨架蛋白和黏附蛋白等.实验证实:带有纳米表面结构的植入材料具有良好的生物相容性和理化特性;纳米表面粗糙程度大大增加,亲水性、电化学特性明显提高,更有利于细胞外基质蛋白等的黏附和相互作用,从而促进成骨细胞黏附、增殖和分化;纳米表面也能促进成骨细胞产生前列腺素E2(prostagIandin E2,PGE2)、转化生长因子β(transforming growth factor-β,TGF-β)等细胞因子,影响新骨形成.纳米表面骨植人材料及其对成骨细胞的影响的作用机制还有待进一步研究.     

Osteoprotegerin (OPG) Production by Cells in the Osteoblast Lineage is Regulated by Pulsed Electromagnetic Fields in Cultures Grown on Calcium Phosphate Substrates

Pulsed electromagnetic fields (PEMF) used clinically to stimulate bone formation enhance the osteogenic effects of BMP-2 on human mesenchymal stem cells (MSCs) if the MSCs are grown in osteogenic medium and are cultured on calcium phosphate (CaP) surfaces rather than tissue culture polystyrene plastic (TCPS). This study tested if PEMF’s effects on cells in the osteoblast lineage are substrate dependent and if factors produced by osteoblasts that regulate osteoclastic bone resorption, might also be regulated by PEMF. Human MSCs treated with BMP-2 and human osteoblast-like cells (normal human osteoblasts [NHOst cells], MG63 cells, SaOS-2 cells) were cultured on CaP or TCPS and their response to PEMF (4.5 ms bursts of 20 pulses repeating at 15 Hz for 8 h/day) determined as a function of decoy receptor osteoprotegerin (OPG) and RANK ligand (RANKL) production, both of which are associated with regulation of osteoclast differentiation. The results showed that when osteoblast-like cells were cultured on CaP, PEMF decreased cell number and increased production of paracrine factors associated with reduced bone resorption like OPG. RANKL was unaffected, indicating that the OPG/RANKL ratio was increased, further supporting a surface-dependent osteogenic effect of PEMF. Moreover, effects of estrogen were surface dependent and enhanced by PEMF, demonstrating that PEMF can modulate osteogenic responses to anabolic regulators of osteoblast function. These effects of PEMF would not be evident in models examining cells in traditional culture on plastic.