0天 - 灭菌前一天的实验<ol><li>材料放入塑料桶和消毒，用70％酒精2小时： <ul><li>钱伯斯</li><li>盖</li><li>相框（3件） </li><li>螺丝</li><li>橡胶垫片</li><li>镊子</li><li>剪刀</li><li>六角扳手</li></ul></li><li>用Aquet肥皂和蒸馏水清洁膜。 </li><li>超声在10分钟的70％的酒精膜。 </li><li>成塑料平方米美食广场的清洁膜。如果使用图案膜，确保图案的一面是面对（到膜的一侧喷酒精和观看的液体运行的凹槽）。 </li><li>保留70％酒精2小时覆盖膜。 </li><li>蒸压明天早上到铝箔包装手套。 </li><li>蒸压明天，蒸馏水的2％（重量/体积）明胶溶液（2g/100mL）。 </li><li>在70％酒精消毒2小时后，放入隔夜紫外线的防护罩所有高分子材料与膜（非高压灭菌材料）： <ul><li>钱伯斯</li><li>盖</li><li>相框（3件） </li><li>膜</li></ul></li><li>包成高温高压灭菌包的剩余材料： <ul><li>螺丝</li><li>橡胶垫片</li><li>镊子</li><li>剪刀</li><li>六角扳手</li></ul></li></ol>第1天 - 拉伸商会大会<ol><li>高压灭菌镊子，剪刀，六角扳手，螺丝，垫圈，手套，并在240 ° F明胶使用总共20分钟的小反应釜</li><li>删除免受紫外线膜和治疗用氧等离子体（图案的一面向上）〜1分钟。 </li><li>在TC罩，封面图案与明胶等离子处理后的膜面积。大衣30紫外光下分钟。 </li><li>每个膜用PBS 2X洗净。第二次洗涤后，留下一些PBS膜，使他们湿滑，更容易进入商会的大会。 （也应该使用此PBS润滑容易装配的垫片）。 </li><li>到商会组装膜（穿在组装过程中的灭菌手套） <ol><li>连接两个帧，使用一台单螺杆主件。 </li><li>翻转帧上放置一个顶部朝框架，使明胶包侧面（图案面积应在中心）膜。 </li><li>安全膜帧，每方使用一个垫片。 </li><li>按垫片，使用温和的，甚至压力，以免撕裂膜。 </li></ol></li><li>将装配架T - BAR。 </li><li>翻转到商会的框架和地方倒挂。框架和膜的紫外线30分钟的背面</li><li>再次翻转帧，并进入商会（控制室没有改变，但舒展室，需要用两个螺丝将这块室底部框架，需要删除的单螺杆螺丝帧的两件）。 30分钟的紫外线前端。确保膜完全干燥，然后再继续下一步，否则电池解决方案可能会滑在播种。 </li><li>种子细胞。 1 = 3膜板区的面积，因此使用一个每膜融合板的1 / 3。使用1毫升每膜细胞液。任何超过1.5ml的将难以跟上解决方案。图案的面积上只放电池解决方案，并用吸头周围传播解决方案。包括商会及让细胞附着在引擎盖RT 30分钟。 </li><li>移动商会孵化器，让细胞附着1小时。移动分庭，以避免让电池解决方案滑落，必须非常小心！如果在这一点上脱落的解决方案，该商会的细胞就会被葬送。 </li><li>返回室罩和添加20毫升媒体。 </li><li>用铝箔覆盖（也用酒精喷洒）酒精清洗浴缸的地方，那就是商会。移动商会舒展孵化器（10％的CO 2）。 </li><li>到拉伸机的安全室。让细胞进一步重视过夜，第二天就开始舒展。 （ 注 ：投入拉伸机室时，请记住“零”的位置锁定在机前放置商会，然后拧紧齿轮周围的橡皮筋不要忘记解锁之前，启动机的齿轮）。 </li></ol>

<ol>
	<li>Banes, A. J., Gilbert, J., Taylor, D., Monbureau, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+vacuum-operated+stress-providing+instrument+that+applies+static+or+variable+duration+cyclic+tension+or+compression+to+cells+in+vitro.">A new vacuum-operated stress-providing instrument that applies static or variable duration cyclic tension or compression to cells in vitro.</a> J Cell Sci. 75, 35-42 (1985).</li><li>Park, J. S., Chu, J. S., Cheng, C., Chen, F., Chen, D., Li, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+effects+of+equiaxial+and+uniaxial+strain+on+mesenchymal+stem+cells.">Differential effects of equiaxial and uniaxial strain on mesenchymal stem cells.</a> Biotechnol. Bioeng. 88, 359-368 (2004).</li><li>Kurpinski, K., Chu, J., Hashi, C., Li, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anisotropic+mechanosensing+by+mesenchymal+stem+cells.">Anisotropic mechanosensing by mesenchymal stem cells.</a> Proc. Natl. Acad. Sci. U S A. 103, 16095-16100 (2006).</li></ol>

巴内斯等。首次报道在体外培养细胞的机械性刺激，通过使用一个灵活的弹性基材提供机械力1细胞的系统使用。这段时间以来，这种设计上的许多变化已经构思和利用。几个机械牵张系统市售的名义下“Flexercell”（Flexcell国际公司），而一些实验室使用定制的设备。在这个视频协议，我们已经描述了一个这样的设备的安装和使用，在我们的实验室。 本议定书中所描述的定制的“拉伸机”已被用来?...

媒体上的注意事项：这些单轴拉伸实验是容易发生污染的生物反应器设置的复杂性。为了解决这个问题，我们已经尝试了各种组合的抗生素和抗真菌剂。 1％fungizone，通常是必要的，随着抗生素的组合。要么使用钢笔/链球菌结合，或用卡那霉素和庆大霉素的组合（但不要尝试使用组合/鸡尾酒三个或更多的抗生素，因为它可能导致抗药性突变的细菌，也可能是有害的细胞） 。

mechanical stimulation of stem cells using cyclic uniaxial strain

在生物组织的发展和维护的机械力的作用是有据可查的，包括几个机械监管的现象，如骨重塑，肌肉肥厚，平滑肌细胞的可塑性。然而，涉及的力量往往是非常复杂和困难的监视和控制体内。为了更好地研究细胞的机械力的影响，我们已经制定了在体外采用单向循环拉伸应变的弹性膜贴壁细胞培养的方法。这种方法采用了机动凸轮转子系统定制设计的生物反应器，以申请所需的力。在这里，我们现在一步一步的视频协议，演示了如何组装的每一个“舒展室”的各个组成部分，在这种情况下，包括micropatterned地形的方向与应变方向的细胞与硅膜。我们还描述了消毒商会，播种到膜细胞，到生物反应器的闭锁室，和调整的力学参数（即幅度和应变率）的程序。在这个特殊的协议中所述的程序，具体到与10微米宽的通道方向平行方向的应变硅膜播种人类间质干细胞。然而，在这个系统中提出的方法和材料是灵活的，足以容纳一个关于这一主题的变化：应变速率，幅度，持续时间，细胞类型，地形膜，膜涂层，等等都可以根据所需的应用程序或的结果。这是一个可靠的方法，调查体外细胞应用于单轴拉伸应变的影响。

Watch this Scientific Journal Video about Mechanical Stimulation of Stem Cells Using Cyclic Uniaxial Strain at JoVE.com

Mechanical Stimulation of Stem Cells Using Cyclic Uniaxial Strain

它被广泛了解，在体内的机械力可以影响细胞分化和增殖。在这里，我们提出了一个视频协议，显示了使用一个定制的生物反应器提供单向循环拉伸应变干细胞培养灵活micropatterned基板。

采用循环单轴应变的干细胞的机械性刺激

The role of mechanical forces in the development and maintenance of biological tissues is well documented, including several mechanically regulated ...

mechanical-stimulation-of-stem-cells-using-cyclic-uniaxial-strain

Research

JoVE Journal

Biology

12.7K 次观看.  University of California, Berkeley. 它被广泛了解，在体内的机械力可以影响细胞分化和增殖。在这里，我们提出了一个视频协议，显示了使用一个定制的生物反应器提供单向循环拉伸应变干细胞培养灵活micropatterned基板。

视频: Mechanical Stimulation of Stem Cells Using Cyclic Uniaxial Strain

Derivation of Hematopoietic Stem Cells from Murine Embryonic Stem Cells

A stem cell is defined as a cell with the capacity to both self-renew and generate multiple differentiated progeny.  Embryonic stem cells (ESC) are derived from the blastocyst of the early embryo and are pluripotent in differentiative ability.  Their vast differentiative potential has made them the focus of much research centered on deducing how to coax them to generate clinically useful cell types.  The successful derivation of hematopoietic stem cells (HSC) from mouse ESC has recently been accomplished and can be visualized in this video protocol.  HSC, arguably the most clinically exploited cell population, are used to treat a myriad of hematopoietic malignancies and disorders.  However, many patients that might benefit from HSC therapy lack access to suitable donors.  ESC could provide an alternative source of HSC for these patients.  The following protocol establishes a baseline from which ESC-HSC can be studied and inform efforts to isolate HSC from human ESC.  In this protocol, ESC are differentiated as embryoid bodies (EBs) for 6 days in commercially available serum pre-screened for optimal hematopoietic differentiation.  EBs are then dissociated and infected with retroviral HoxB4.  Infected EB-derived cells are plated on OP9 stroma, a bone marrow stromal cell line derived from the calvaria of  M-CSF-/- mice, and co-cultured in the presence of hematopoiesis promoting cytokines for ten days.  During this co-culture, the infected cells expand greatly, resulting in the generation a heterogeneous pool of 100s of millions of cells.  These cells can then be used to rescue and reconstitute lethally irradiated mice.

This protocol details the derivation of transplantable hematopoietic stem cells from mouse embryonic stem cells (ESC) and their subsequent injection into lethally irradiated recipient mice. Briefly, ESC are differentiated as embryoid bodies, which are then infected with retroviral HoxB4 and co-cultured with OP9 stromal cells and hematopoietic cytokines.

从小鼠胚胎干细胞的造血干细胞的推导

A stem cell is defined as a cell with the capacity to both self-renew and generate multiple differentiated progeny.  Embryonic stem cells (ESC) are ...

科研

生物学

Patterning of Embryonic Stem Cells Using the Bio Flip Chip

Cell-cell interactions consisting of diffusible signaling and cell-cell contact (juxtacrine signaling) are important in numerous biological processes such as tumor growth, stem cell differentiation, and stem cell self-renewal. A number of methods currently exist to modulate cell signaling in vitro. One method of modulating the total amount of diffusible signaling is to vary the cell seeding density during culture. Due to the random nature of cell seeding, this results in considerable variation in the actual cell-cell spacing and amount of cell-cell contact, and cannot prescribe the local environment. A more specific approach for modulating cell signaling is to use molecular inhibitors or genetic approaches to knock down specific signaling proteins, but both of these methods are best suited to manipulating small numbers of molecules. Here, we demonstrate a new approach to modulating cell-cell signaling that modulates the local environment of a cluster of cells by placing different numbers of cells at desired locations on a substrate. This method provides a complementary way to control the local diffusible and juxtacrine signaling between cells. Our method makes use of the Bio Flip Chip (BFC), a microfabricated silicone chip containing hundreds-to-thousands of microwells, each sized to hold either a single cell or small numbers of cells. We load the chip with cells simply by pipetting them onto the array of wells and washing unloaded cells off the array. The chip is then flipped onto a substrate, whereby the cells fall out of the wells and onto the substrate, maintaining their patterning. After the cells have attached, the chip can be removed (or left on). This approach to cell patterning is unique in that it: 1) doesn't alter the chemistry of the substrate, thus allowing cells to proliferate and migrate; 2) allows patterning onto any substrate, including tissue-culture polystyrene, glass, matrigel, and even feeder cell layers; and 3) is compatible with traditional microcontact printing, allowing the creation of extracellular matrix islands with cells placed inside those islands. In this video, we demonstrate the patterning of mouse embryonic stem cells onto tissue-culture polystyrene using the BFC.

We demonstrate a simple method for placing cells at desired locations on a substrate. This method patterns cells by flipping a silicone chip containing microwells filled with cells onto the substrate. This method provides a new way to modulate diffusible and juxtacrine signaling between cells.

图案的使用生物倒装芯片的胚胎干细胞

Cell-cell interactions consisting of diffusible signaling and cell-cell contact (juxtacrine signaling) are important in numerous biological processes such ...

Live Cell Response to Mechanical Stimulation Studied by Integrated Optical and Atomic Force Microscopy

To understand the mechanism by which living cells sense mechanical forces, and how they respond and adapt to their environment, a new technology able to investigate cells behavior at sub-cellular level with high spatial and temporal resolution was developed. Thus, an atomic force microscope (AFM) was integrated with total internal reflection fluorescence (TIRF) microscopy and fast-spinning disk (FSD) confocal microscopy. The integrated system is broadly applicable across a wide range of molecular dynamic studies in any adherent live cells, allowing direct optical imaging of cell responses to mechanical stimulation in real-time. Significant rearrangement of the actin filaments and focal adhesions was shown due to local mechanical stimulation at the apical cell surface that induced changes into the cellular structure throughout the cell body. These innovative techniques will provide new information for understanding live cell restructuring and dynamics in response to mechanical force. A detailed protocol and a representative data set that show live cell response to mechanical stimulation are presented.

This paper aims to instruct the reader in the operation of an integrated atomic force-optical imaging microscope for mechanical stimulation of live cells in culture. A step-by-step protocol is presented. A representative data set that shows live cell response to mechanical stimulation is presented.

机械性刺激，集成光学和原子力显微镜研究活细胞的反应

To understand the mechanism by which living cells sense mechanical forces, and how they respond and adapt to their environment, a new technology able to ...

Analysis of Pluripotent Stem Cells by using Cryosections of Embryoid Bodies

Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of blastocyst-stage early mammalian embryos 1. A crucial stage in the differentiation of ES cells is the formation of embryoid bodies (EBs) aggregates 2, 3. EB formation is based on spontaneous aggregation when ES cells are cultured in non adherent plates. Three-dimensional EB recapitulates many aspects of early mammalian embryogenesis and differentiate into the three germ layers: ectoderm, mesoderm and endoderm 4.
Immunofluorescence and in situ hybridization are widely used techniques for the detection of target proteins and mRNA present in cells of a tissue section 5, 6, 7. Here we present a simple technique to generate high quality cryosections of embryoid bodies. This approach relies on the spatial orientation of EB embedding in OCT followed by the cryosection technique. The resulting sections can be subjected to a wide variety of analytical procedures in order to characterize populations of cells containing certain proteins, RNA or DNA. In this sense, the preparation of EB cryosections (10&mu;m) are essential tools for histology staining analysis (e.g. Hematoxilin and Eosin, DAPI), immunofluorescence (e.g. Oct4, nestin) or in situ hybridization. This technique can also help to understand aspects of embryogenesis with regards to the maintenance of the tri-dimensional spherical structure of EBs.

Pluripotent stem cells growing in suspension differentiate into embryoid bodies (EBs). Here we demonstrate how to obtain high quality EB cryosections useful for studying cellular and molecular aspects of embryogenesis, while preserving their organization as aggregates.

使用胚体冰冻切片分析的多能干细胞

Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of blastocyst-stage early mammalian embryos 1. A crucial stage in the ...

Quantifying the Frequency of Tumor-propagating Cells Using Limiting Dilution Cell Transplantation in Syngeneic Zebrafish

Self-renewing cancer cells are the only cell types within a tumor that have an unlimited ability to promote tumor growth, and are thus known as tumor-propagating cells, or tumor-initiating cells. It is thought that targeting these self-renewing cells for destruction will block tumor progression and stop relapse, greatly improving patient prognosis1. The most common way to determine the frequency of self-renewing cells within a tumor is a limiting dilution cell transplantation assay, in which tumor cells are transplanted into recipient animals at increasing doses; the proportion of animals that develop tumors is used the calculate the number of self-renewing cells within the original tumor sample2, 3. Ideally, a large number of animals would be used in each limiting dilution experiment to accurately determine the frequency of tumor-propagating cells. However, large scale experiments involving mice are costly, and most limiting dilution assays use only 10-15 mice per experiment. 
Zebrafish have gained prominence as a cancer model, in large part due to their ease of genetic manipulation and the economy by which large scale experiments can be performed. Additionally, the cancer types modeled in zebrafish have been found to closely mimic their counterpart human disease4. While it is possible to transplant tumor cells from one fish to another by sub-lethal irradiation of recipient animals, the regeneration of the immune system after 21 days often causes tumor regression5. The recent creation of syngeneic zebrafish has greatly facilitated tumor transplantation studies 6-8. Because these animals are genetically identical, transplanted tumor cells engraft robustly into recipient fish, and tumor growth can be monitored over long periods of time. Syngeneic zebrafish are ideal for limiting dilution transplantation assays in that tumor cells do not have to adapt to growth in a foreign microenvironment, which may underestimate self-renewing cell frequency9, 10. Additionally, one-cell transplants have been successfully completed using syngeneic zebrafish8 and several hundred animals can be easily and economically transplanted at one time, both of which serve to provide a more accurate estimate of self-renewing cell frequency.
Here, a method is presented for creating primary, fluorescently-labeled T-cell acute lymphoblastic leukemia (T-ALL) in syngeneic zebrafish, and transplanting these tumors at limiting dilution into adult fish to determine self-renewing cell frequency. While leukemia is provided as an example, this protocol is suitable to determine the frequency of tumor-propagating cells using any cancer model in the zebrafish.

Limiting dilution cell transplantation assays are used to determine the frequency of tumor-propagating cells. This protocol describes a method for generating syngeneic zebrafish that develop fluorescently-labeled leukemia and details how to isolate and transplant these leukemia cells at limiting dilution into the peritoneal cavity of adult zebrafish.

量化传播肿瘤细胞的频率使用斑马鱼的同源有限稀释细胞移植

Self-renewing cancer cells are the only cell types within a tumor that have an unlimited ability to promote tumor growth, and are thus known as ...

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Matrix stiffness strongly influences growth, differentiation and function of adherent cells1-3. On the macro scale the stiffness of tissues and organs within the human body span several orders of magnitude4. Much less is known about how stiffness varies spatially within tissues, and what the scope and spatial scale of stiffness changes are in disease processes that result in tissue remodeling. To better understand how changes in matrix stiffness contribute to cellular physiology in health and disease, measurements of tissue stiffness obtained at a spatial scale relevant to resident cells are needed. This is particularly true for the lung, a highly compliant and elastic tissue in which matrix remodeling is a prominent feature in diseases such as asthma, emphysema, hypertension and fibrosis. To characterize the local mechanical environment of lung parenchyma at a spatial scale relevant to resident cells, we have developed methods to directly measure the local elastic properties of fresh murine lung tissue using atomic force microscopy (AFM) microindentation. With appropriate choice of AFM indentor, cantilever, and indentation depth, these methods allow measurements of local tissue shear modulus in parallel with phase contrast and fluorescence imaging of the region of interest. Systematic sampling of tissue strips provides maps of tissue mechanical properties that reveal local spatial variations in shear modulus. Correlations between mechanical properties and underlying anatomical and pathological features illustrate how stiffness varies with matrix deposition in fibrosis. These methods can be extended to other soft tissues and disease processes to reveal how local tissue mechanical properties vary across space and disease progression.

The stiffness of the extracellular matrix strongly influences multiple behaviors of adherent cells. Matrix stiffness varies spatially throughout a tissue, and undergoes modification in various disease conditions. Here we develop methods to characterize spatial variations in stiffness in normal and fibrotic mouse lung tissue using atomic force microscopy microindentation.

微型机械的肺组织利用原子力显微镜表征

Matrix stiffness strongly influences growth, differentiation and function of adherent cells1-3.  On the macro scale the stiffness of tissues and organs ...

Biophysical Assays to Probe the Mechanical Properties of the Interphase Cell Nucleus: Substrate Strain Application and Microneedle Manipulation

In most eukaryotic cells, the nucleus is the largest organelle and is typically 2 to 10 times stiffer than the surrounding cytoskeleton; consequently, the physical properties of the nucleus contribute significantly to the overall biomechanical behavior of cells under physiological and pathological conditions. For example, in migrating neutrophils and invading cancer cells, nuclear stiffness can pose a major obstacle during extravasation or passage through narrow spaces within tissues.1 On the other hand, the nucleus of cells in mechanically active tissue such as muscle requires sufficient structural support to withstand repetitive mechanical stress. Importantly, the nucleus is tightly integrated into the cellular architecture; it is physically connected to the surrounding cytoskeleton, which is a critical requirement for the intracellular movement and positioning of the nucleus, for example, in polarized cells, synaptic nuclei at neuromuscular junctions, or in migrating cells.2 Not surprisingly, mutations in nuclear envelope proteins such as lamins and nesprins, which play a critical role in determining nuclear stiffness and nucleo-cytoskeletal coupling, have been shown recently to result in a number of human diseases, including Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy, and dilated cardiomyopathy.3 To investigate the biophysical function of diverse nuclear envelope proteins and the effect of specific mutations, we have developed experimental methods to study the physical properties of the nucleus in single, living cells subjected to global or localized mechanical perturbation. Measuring induced nuclear deformations in response to precisely applied substrate strain application yields important information on the deformability of the nucleus and allows quantitative comparison between different mutations or cell lines deficient for specific nuclear envelope proteins. Localized cytoskeletal strain application with a microneedle is used to complement this assay and can yield additional information on intracellular force transmission between the nucleus and the cytoskeleton. Studying nuclear mechanics in intact living cells preserves the normal intracellular architecture and avoids potential artifacts that can arise when working with isolated nuclei. Furthermore, substrate strain application presents a good model for the physiological stress experienced by cells in muscle or other tissues (e.g., vascular smooth muscle cells exposed to vessel strain). Lastly, while these tools have been developed primarily to study nuclear mechanics, they can also be applied to investigate the function of cytoskeletal proteins and mechanotransduction signaling.

We present two independent, microscope-based tools to measure the induced nuclear and cytoskeletal deformations in single, living adherent cells in response to global or localized strain application. These techniques are used to determine nuclear stiffness (i.e., deformability) and to probe intracellular force transmission between the nucleus and the cytoskeleton.

生物物理检测探头相间细胞核的力学性能：基材应变的应用和微针操纵

In most eukaryotic cells, the nucleus is the largest organelle and is typically 2 to 10 times stiffer than the surrounding cytoskeleton; consequently, the ...

Reprogramming Human Somatic Cells into Induced Pluripotent Stem Cells (iPSCs) Using Retroviral Vector with GFP

Human embryonic stem cells (hESCs) are pluripotent and an invaluable cellular sources for in vitro disease modeling and regenerative medicine1. It has been previously shown that human somatic cells can be reprogrammed to pluripotency by ectopic expression of four transcription factors (Oct4, Sox2, Klf4 and Myc) and become induced pluripotent stem cells (iPSCs)2-4 . Like hESCs, human iPSCs are pluripotent and a potential source for autologous cells. Here we describe the protocol to reprogram human fibroblast cells with the four reprogramming factors cloned into GFP-containing retroviral backbone4. Using the following protocol, we generate human iPSCs in 3-4 weeks under human ESC culture condition. Human iPSC colonies closely resemble hESCs in morphology and display the loss of GFP fluorescence as a result of retroviral transgene silencing. iPSC colonies isolated mechanically under a fluorescence microscope behave in a similar fashion as hESCs. In these cells, we detect the expression of multiple pluripotency genes and surface markers.

Reprogramming Human Somatic Cells into Induced Pluripotent Stem Cells iPSCs Using Retroviral Vector with GFP

A method to generate human induced pluripotent stem cells (iPSCs) via retrovirus-mediated ectopic expression of OCT4, SOX2, KLF4 and MYC is described. A practical way to identify human iPSC colonies based on GFP expression is also discussed.

人类体细胞重编程为诱导多能干细胞（iPS细胞）用绿色荧光蛋白逆转录病毒载体

Human embryonic stem cells (hESCs) are pluripotent and an invaluable cellular sources for in vitro disease modeling and regenerative medicine1. It has ...

Mechanical Stimulation of Chondrocyte-agarose Hydrogels

Articular cartilage suffers from a limited repair capacity when damaged by mechanical insult or degraded by disease, such as osteoarthritis. To remedy this deficiency, several medical interventions have been developed. One such method is to resurface the damaged area with tissue-engineered cartilage; however, the engineered tissue typically lacks the biochemical properties and durability of native cartilage, questioning its long-term survivability. This limits the application of cartilage tissue engineering to the repair of small focal defects, relying on the surrounding tissue to protect the implanted material. To improve the properties of the developed tissue, mechanical stimulation is a popular method utilized to enhance the synthesis of cartilaginous extracellular matrix as well as the resultant mechanical properties of the engineered tissue. Mechanical stimulation applies forces to the tissue constructs analogous to those experienced in vivo. This is based on the premise that the mechanical environment, in part, regulates the development and maintenance of native tissue1,2. The most commonly applied form of mechanical stimulation in cartilage tissue engineering is dynamic compression at physiologic strains of approximately 5-20% at a frequency of 1 Hz1,3. Several studies have investigated the effects of dynamic compression and have shown it to have a positive effect on chondrocyte metabolism and biosynthesis, ultimately affecting the functional properties of the developed tissue4-8. In this paper, we illustrate the method to mechanically stimulate chondrocyte-agarose hydrogel constructs under dynamic compression and analyze changes in biosynthesis through biochemical and radioisotope assays. This method can also be readily modified to assess any potentially induced changes in cellular response as a result of mechanical stimuli.

The biosynthesis of cartilaginous extracellular matrix by chondrocytes can be affected by application of mechanical stimuli. This method describes the technique of applying dynamic compressive strains to chondrocytes encapsulated in 3D constructs and the evaluation of induced changes in chondrocyte metabolism.

机械性刺激软骨细胞琼脂糖凝胶

Articular cartilage suffers from a limited repair capacity when damaged by mechanical insult or degraded by disease, such as osteoarthritis. To remedy ...

Mechanical Stimulation-induced Calcium Wave Propagation in Cell Monolayers: The Example of Bovine Corneal Endothelial Cells

Intercellular communication is essential for the coordination of physiological processes between cells in a variety of organs and tissues, including the brain, liver, retina, cochlea and vasculature. In experimental settings, intercellular Ca2+-waves can be elicited by applying a mechanical stimulus to a single cell. This leads to the release of the intracellular signaling molecules IP3 and Ca2+ that initiate the propagation of the Ca2+-wave concentrically from the mechanically stimulated cell to the neighboring cells. The main molecular pathways that control intercellular Ca2+-wave propagation are provided by gap junction channels through the direct transfer of IP3 and by hemichannels through the release of ATP. Identification and characterization of the properties and regulation of different connexin and pannexin isoforms as gap junction channels and hemichannels are allowed by the quantification of the spread of the intercellular Ca2+-wave, siRNA, and the use of inhibitors of gap junction channels and hemichannels. Here, we describe a method to measure intercellular Ca2+-wave in monolayers of primary corneal endothelial cells loaded with Fluo4-AM in response to a controlled and localized mechanical stimulus provoked by an acute, short-lasting deformation of the cell as a result of touching the cell membrane with a micromanipulator-controlled glass micropipette with a tip diameter of less than 1 &mu;m. We also describe the isolation of primary bovine corneal endothelial cells and its use as model system to assess Cx43-hemichannel activity as the driven force for intercellular Ca2+-waves through the release of ATP. Finally, we discuss the use, advantages, limitations and alternatives of this method in the context of gap junction channel and hemichannel research.

Intercellular Ca2+-waves are driven by gap junction channels and hemichannels. Here, we describe a method to measure intercellular Ca2+-waves in cell monolayers in response to a local single-cell mechanical stimulus and its application to investigate the properties and regulation of gap junction channels and hemichannels.

机械刺激引起的钙波传播的细胞单层：牛角膜内皮细胞的例子

Intercellular communication is essential for the coordination of physiological processes between cells in a variety of organs and tissues, including the ...