支持这项工作是由美国凯斯西储大学的生物医学工程部通过两个实验室启动资金（J. Capadona），美敦力的研究生奖学金（K.波特）。在此研究中，额外的资金支持部分由NSF资助ECS-0621984（C. Zorman），案例校友协会（C. Zorman）通过优异评论奖（B7122R），退伍军人事务部，以及高级平台技术中心（C3819C）。

1。样品制备<ol><li>制备聚醋酸乙烯酯-NC膜的厚度在25-100微米的范围内使用溶液流延法和压缩技术10-12。 </li><li>粘附膜的硅晶片上的热板上加热两分钟，在70℃（玻璃化转变温度以上），以促进膜和晶片之间的紧密接触。此步骤可确保所制备的膜的硅晶片，这是必要的平面的微机械加工工艺保持平整，并且固定。 </li><li>通过激光微加工（VLS 3.50，VersaLASER）到测试样品几何图案的电影。 CO 2的直接写入的激光微加工参数设置2.0％的功率（0.5 W），8.0％的速度（56毫米/秒），和每英寸1000个脉冲13,16。 </li><li>模式标本将用于建立为狗骨头形状的结构与侧焊盘尺寸1.5×1.5平方毫米 ，外侧束昏暗的环境条件（“设置样本”）ensions 300×3,000μm2的厚度匹配，该膜在整个（ 图2）。 </li><li>柄体外实验样品（“植入物样本”）成束为300μm×6毫米，具有厚度的膜相匹配的。 </li><li>从晶片用剃刀刀片和镊子小心地释放样品。 </li><li>样品处理，准备定制加工设计的丙烯酸持有人作为微拉伸测试仪握系统的一部分。激光蚀刻的标记显示在支架的中心线，从端部150毫米。将少量凝胶氰基丙烯酸酯系粘接剂，丙烯酸类持有人的中心线，并小心地坚持1.5毫米长的样品的支架的植入物和重叠标记的中心线（ 图3）。每个种植体样本需要一种丙烯酸持有人。要小心，以确保粘合剂凝胶仍然只能沿着坚持ACR PVAC-NC 1.5毫米的长度噻持有人。否则，该粘合胶可干扰的样品的机械性能。 </li><li>从所有样品通过将它们放置在干燥器中至少24小时，除去水分。 </li><li>测量使用光学显微镜的样品的长度，宽度和厚度的尺寸。 </li></ol> 2。建立环境条件<ol><li>装入干燥的微拉伸测试仪（ 见图4），设置样品放入第一夹紧之间的移动把手之间，然后固定夹具。 </li><li>安装一个空气刷与一个装满水的储到一个固定的位置，与喷嘴朝向微拉伸试样。将空气刷到一个空气压缩机，通过塑料管。随着空气刷喷嘴完全封闭，打开空气压缩机上。 </li><li>开始循环微拉伸测试过程中，拉伸应变（正应变）和压缩应变（负应变）应用到t之间交替他样品，剩余的线性弹性区域内的应力 - 应变曲线。对于聚醋酸乙烯酯-NC，所施加的应变被限制到小于2％。在这些实验中使用的自定义的微拉伸测试仪，应变速率的控制，而所需要的力来实现，该菌株测定。另外，可能涉及不同的设置控制所施加的力，而由此产生的应变测量。 </li><li>逐渐增加的流量从空气刷喷嘴，并监视流从空气刷的量的函数的应力 - 应变曲线的斜率。不会导致显着性（&gt; 10％）的杨氏模量超过60秒的一段时间的减少的最大流量水平，将用于体外实验。在这一点上，在湿度条件下，将不会湿润干燥的样品（并因此向的杨氏模量的降低），也将减少在被暴露在体内的生物体液样品干燥已被静电喷涂blished。 </li><li>测量的样品附近的温度。一个理想的设置将包括一个数字读出热电偶，喷枪运行时进行。设置辐射热源，使得样品的温度保持37℃，符合生理条件下的强度和距离。 </li></ol> 3。比较非环境控制环境控制<ol><li>设置浸入样品进行至少30分钟在磷酸盐缓冲盐水。在此之后的时间量，样品是完全饱和的，已经降低到其最低的杨氏模量在给定温度。 </li><li>快速加载到微拉伸测试仪样品，并开始循环的微拉伸测试，用空气刷过，而样品干了。这将决定如何快速的样品在非受控条件下干燥。 </li><li>微拉伸测试仪装入第二个设置样品放入PBS饱和，并开始循环的微拉伸测试的空气刷上。这将决定如何快速的样品在控制的环境条件下干燥。 </li></ol> 4。探针植入和外植<ol><li>将植入物样品的一个显微钳和正交位置的皮层组织。 </li><li>在插入之前，保持组织足够用生理盐水湿润以确保同质化的组织力学。 </li><li>降低聚合物样品到皮质使用的显微手控制。留下皮层组织样本，直到的目标植入物的时间，一般在1和30分钟之间。为了防止组织干燥时间点，超过5分钟，轻轻民建联组织每隔5分钟用盐水浸泡过的棉签。 </li><li>皮层植入探针时，制备的微拉伸测试仪，用于加载当前注入的样品通过设置驱动杆从固定样品夹为3.0mm的零位移位置。此外，设置空气刷喷嘴流设置到适当的强度，确定在步骤2.4中的辐射热源。 </li><li>在指定的植入时间的结束，提高探头的皮质使用的显微手控制。随即，并小心的是，取出样品的显微钳和加载到微拉伸测试仪，在步骤5.2中更详细地描述。 </li></ol> 5。牙本质植入样品测试<ol><li>为了节省时间外植后，确保微拉伸测试仪完全准备好接受种植体的样品植入前，中所描述的步骤4.4。 </li><li>紧随外植后，装入样品两套之间的微拉伸测试仪夹。由于样品被安装到丙烯酸类保持器设计为作为一个夹具的上半部分中，将所述植入物的样本组件上移动的抓地力，样品的一面朝下。重要的是要确保样本被安装使得菌株APPLIED 仅沿其长度的探针，以避免在测试过程中施加扭矩样品。因此，样品必须被安装到每个夹子的中心，和夹具必须相对于彼此水平。 </li><li>调整样品的位置，使得夹具之间的距离为3.0 mm，在探头的端部被放置到固定钳。此3.0毫米夹具间的长度为样品的标距长度，并在以后的计算中，将被用于确定在样品上的应变。 </li><li>后立即固定在这两个夹具之间的试样，并在2分钟内从神经组织的外植，激活电机在拉伸方向上细长的样品以恒定的速率（10微米/秒这里使用的），同时测量和记录样品的伸长率（使用位移指示器，Mitutoyu 543-561）和相关的应变样品所需的力（使用测力传感器，换能器技术的MDB-2.5）。 </li><l&gt;暂停的微拉伸试验后的样品的机械故障时，或当驱动杆范围的末尾达到。输出所收集的数据，并进行数据分析。 </li><li>重复的微拉伸，每个样品的测试和/或每一组的条件（ 即插入时间）。 </li></ol> 6。数据分析<ol><li>原料的伸长率数据转换于工程应变施加到植入物的样品通过的距离除以伸长的初始标距长度，方程1中所描述的，其中，ε是所施加的应变，t是时间，d是由千分尺测量的位移指示器，和L 0是样品的初始标距长度： <img src="/files/ftp_upload/50078/50078eq1.jpg" alt="公式1" fo:src="/files/ftp_upload/50078/50078eq1highres.jpg"/> （1） </li><li>原力数据转换的工程应力除以样品上的力（牛顿），通过传统nsverse的横截面面积，公式（2）中所描述的： <img src="/files/ftp_upload/50078/50078eq2.jpg" alt="公式（2）" fo:src="/files/ftp_upload/50078/50078eq2highres.jpg"/> （2） 其中σ是在样品上的应力，F是由测力传感器测得的力（牛顿）， 瓦特0是样品的初始宽度，t 0是样品的初始厚度。 </li><li>绘制应力（σ[T]）与应变（ε[T]）每个样品使用的计算机程序，如Microsoft Excel的曲线。 </li><li>隔离的情节的线状弹性部，并使用基于软件的曲线拟合工具，以找到最好的拟合线，以该部分。最佳拟合线的斜率对应于样品的杨氏模量。的情节的隔离部分应包括至少10应力 - 应变点，应该从斜率为最大的部分的情节。 </li><li>对于循环试验，杨氏模量将需要被确定的每个周期。这可以自动或手动执行。 </li><li>对于循环试验，情节的杨氏模量随时间变化的每个周期。这表明如何测得的弹性模量随时间的变化，这是表示设置样品如何迅速地润湿或干燥。 </li><li>对于植入物的样品，每个样品和时间种植体对应于一个周期内的循环试验。测量的杨氏模量，使用上面描述的过程对每个植入物样品。 </li><li>绘制的杨氏模量与植入时间。在这一点上，比较，可以向台式调查，等</li></ol>

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我们什么都没有透露。

可植入生物医学微电子机械系统（微机电）与生物系统进行交互的进步是激励具有高度定制的特性的新材料的发展。其中一些材料的设计表现出材料性能的变化，发现在生理环境中对刺激的响应。一个最近开发的一类材料氢键形成的液体（ 例如水）和高温下的杨氏模量，材料的刚度的措施，减少了三个数量级10,11,18的存在下的反应。这些聚合物纳米复合材料具有柔软的聚合物基体?...

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			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalogue Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Silicon wafer</td>
			<td>University Wafer</td>
			<td>&nbsp;</td>
			<td>Mechanical grade</td>
		</tr>
		<tr>
			<td>Extruded acrylic sheet</td>
			<td>Professional Plastics</td>
			<td>SACR 062EF</td>
			<td>Thickness 0.062"</td>
		</tr>
		<tr>
			<td>Razor blade</td>
			<td>McMaster-Carr</td>
			<td>3962A3</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Tweezers</td>
			<td>McMaster-Carr</td>
			<td>8384A47</td>
			<td>#5 tip</td>
		</tr>
		<tr>
			<td>Super Glue Gel</td>
			<td>Loctite</td>
			<td>130380</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Air Brush</td>
			<td>Snap-on Industrial</td>
			<td>BF175TA</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Air Compressor</td>
			<td>Paasche</td>
			<td>B002YKN8YO</td>
			<td>D500</td>
		</tr>
		<tr>
			<td>Thermocouple</td>
			<td>Omega</td>
			<td>HH12A</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Hot plate</td>
			<td>Cimarec</td>
			<td>SP131325Q</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>CO2 direct-write laser</td>
			<td>VersaLaser</td>
			<td>3.5</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Dessicator</td>
			<td>Fisher Scientific</td>
			<td>08-595</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Lamp</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>custom-built</td>
		</tr>
		<tr>
			<td>Microtensile tester</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>custom-built</td>
		</tr>
	</tbody>
</table>

environmentally-controlled microtensile testing of mechanically-adaptive polymer nanocomposites for ex vivo characterization

植入微型器件获得重大关注的几个生物医学应用1-4。这样的设备已经从一系列的材料，提供自己的优点和缺点5,6。最突出的是，由于微尺度装置尺寸，高的弹性模量是必需的，以便植入到生物体组织。相反，该设备的刚度应与周围组织的匹配，以尽量减少引起的局部应变7-9。因此，我们最近开发的一类新的仿生材料，以满足这些要求，通过响应对环境刺激的机械性能的变化10-14。具体而言，为聚（乙酸乙烯酯）为基础的纳米复合材料（聚醋酸乙烯酯-NC）显示一个刚度降低时，接触到水和升高的温度（ 例如体温）。不幸的是，一些方法存在量化材料在体内 15的刚度，机甲外anical测试的生理环境，往往需要大样本，不适合植入。此外，刺激响应材料外植后可能会很快恢复其初始刚度。因此，我们已经开发了一种方法，通过它的机械性能植入microsamples可以测量体外模拟生理条件下保持使用的湿度和温度控制13,16,17。 为此，一个自定义的微拉伸测试仪的设计，以适应广泛不同的杨氏模量（在10MPa至5 GPA所在的范围）的微型样品13,17。由于大家的利益是在PVAC-NC的应用作为一种生物适应性神经探针底物，工具，能够在微尺度样本是必要的机械特性。这个工具被改编提供湿度和温度控制，干燥，冷却17最小化样本。其结果，技工密切反映这些人的特点，植样品的样品之前外植。 该方法的总体目标是在体内的机械性能，特别的刺激响应性，机械自适应聚合物为基础的材料的杨氏模量，定量评估。这是通过首先建立的环境条件下，将外植后的样品的机械性能的变化最小化，而不有助于减少刚度无关，因植入。制备的样品，然后注入，处理，和检测（ 图1A）。大鼠大脑皮质这里取出的大鼠脑组织，在指定的持续时间（ 图1B），这是代表每个样品的注入。在这一点上，将样品取出的，并立即装入的微拉伸测试仪，然后进行拉伸试验（ 图1C）。随后的数据分析提供了洞察这些创新材料的力学行为在大脑皮质的环境。

几乎所有的聚合物材料，包括聚醋酸乙烯酯-NC的机械性能取决于暴露于环境条件。最值得注意的是，这些包括对热和湿气的曝光。被塑化的材料时，由于水分的吸收，或经历了一个热转变时，它显示的杨氏模量的降低。在制备的水分的体外样品的机械特性和温度受控制的环境中，这是重要的，以确保有样品的水分含量非常少的改变，同时将样品加载到微拉伸测试仪，以及在机械测试。评估?...

Watch this Scientific Journal Video about Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization at JoVE.com

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

一种方法的讨论<em&gt;在体内</em&gt;刺激响应性材料的机械行为进行监测作为时间的函数。测试样品<em&gt;体外</em&gt;与环境控制用微拉伸测试仪模拟生理环境。这项工作进一步促进理解<em&gt;在体内</em我们的材料行为。

环境控制机械自适应聚合物纳米复合材料的微拉伸测试<em&gt;体外</em&gt;表征

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

environmentally-controlled-microtensile-testing-mechanically-adaptive

Research

JoVE Journal

Bioengineering

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

10.1K 次观看.  Louis Stokes Cleveland Department of Veterans Affairs Medical Center. 一种方法的讨论在体内刺激响应性材料的机械行为进行监测作为时间的函数。测试样品体外与环境控制用微拉伸测试仪模拟生理环境。这项工作进一步促进理解在体内

视频: Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

循环压力为生物反应器的设计体外主动脉心脏瓣膜的研究

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

科研

生物工程

Ex vivo Mimicry of Normal and Abnormal Human Hematopoiesis

Hematopoietic stem cells require a unique microenvironment in order to sustain blood cell formation1; the bone marrow (BM) is a complex three-dimensional (3D) tissue wherein hematopoiesis is regulated by spatially organized cellular microenvironments termed niches2-4. The organization of the BM niches is critical for the function or dysfunction of normal or malignant BM5. Therefore a better understanding of the in vivo microenvironment using an ex vivo mimicry would help us elucidate the molecular, cellular and microenvironmental determinants of leukemogenesis6.
Currently, hematopoietic cells are cultured in vitro in two-dimensional (2D) tissue culture flasks/well-plates7 requiring either co-culture with allogenic or xenogenic stromal cells or addition of exogenous cytokines8. These conditions are artificial and differ from the in vivo microenvironment in that they lack the 3D cellular niches and expose the cells to abnormally high cytokine concentrations which can result in differentiation and loss of pluripotency9,10.
Herein, we present a novel 3D bone marrow culture system that simulates the in vivo 3D growth environment and supports multilineage hematopoiesis in the absence of exogenous growth factors. The highly porous scaffold used in this system made of polyurethane (PU), facilitates high-density cell growth across a higher specific surface area than the conventional monolayer culture in 2D11. Our work has indicated that this model supported the growth of human cord blood (CB) mononuclear cells (MNC)12 and primary leukemic cells in the absence of exogenous cytokines. This novel 3D mimicry provides a viable platform for the development of a human experimental model to study hematopoiesis and to explore novel treatments for leukemia.

Ex vivo Mimicry of Normal and Abnormal Human Hematopoiesis

A 3D culture system for hematopoiesis is described using human cord blood and leukemic bone marrow cells. The method is based on the use of a porous synthetic polyurethane scaffold coated with extracellular matrix proteins. This scaffold is adaptable to accommodate a wide range of cells.

体外拟态正常与异常的人造血

Hematopoietic stem cells require a unique microenvironment in order to sustain blood cell formation1; the bone marrow (BM) is a complex three-dimensional ...

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced birth defects and many later studies afterwards proved the opposite. Today several harmful xenobiotics like nicotine, heroin, methadone or drugs as well as environmental pollutants were described to overcome this barrier. With the growing use of nanotechnology, the placenta is likely to come into contact with novel nanoparticles either accidentally through exposure or intentionally in the case of potential nanomedical applications. Data from animal experiments cannot be extrapolated to humans because the placenta is the most species-specific mammalian organ 1. Therefore, the ex vivo dual recirculating human placental perfusion, developed by Panigel et al. in 1967 2 and continuously modified by Schneider et al. in 1972 3, can serve as an excellent model to study the transfer of xenobiotics or particles.
Here, we focus on the ex vivo dual recirculating human placental perfusion protocol and its further development to acquire reproducible results.
The placentae were obtained after informed consent of the mothers from uncomplicated term pregnancies undergoing caesarean delivery. The fetal and maternal vessels of an intact cotyledon were cannulated and perfused at least for five hours. As a model particle fluorescently labelled polystyrene particles with sizes of 80 and 500 nm in diameter were added to the maternal circuit. The 80 nm particles were able to cross the placental barrier and provide a perfect example for a substance which is transferred across the placenta to the fetus while the 500 nm particles were retained in the placental tissue or maternal circuit. The ex vivo human placental perfusion model is one of few models providing reliable information about the transport behavior of xenobiotics at an important tissue barrier which delivers predictive and clinical relevant data.

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

The ex vivo dual recirculating human placental perfusion model can be used to investigate the transfer of xenobiotics and nanoparticles across the human placenta. In this video protocol we describe the equipment and techniques required for a successful execution of a placenta perfusion.

通过胎盘的外来物质和纳米材料的运输率测定<em&gt;体外</em&gt;人胎盘灌注型号

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced ...

Imaging Denatured Collagen Strands In vivo and Ex vivo via Photo-triggered Hybridization of Caged Collagen Mimetic Peptides

Collagen is a major structural component of the extracellular matrix that supports tissue formation and maintenance. Although collagen remodeling is an integral part of normal tissue renewal, excessive amount of remodeling activity is involved in tumors, arthritis, and many other pathological conditions. During collagen remodeling, the triple helical structure of collagen molecules is disrupted by proteases in the extracellular environment. In addition, collagens present in many histological tissue samples are partially denatured by the fixation and preservation processes. Therefore, these denatured collagen strands can serve as effective targets for biological imaging. We previously developed a caged collagen mimetic peptide (CMP) that can be photo-triggered to hybridize with denatured collagen strands by forming triple helical structure, which is unique to collagens. The overall goals of this procedure are i)&#160;to image denatured collagen strands resulting from normal remodeling activities in vivo, and ii) to visualize collagens in ex vivo tissue sections using the photo-triggered caged CMPs. To achieve effective hybridization and successful in vivo and ex vivo imaging, fluorescently labeled caged CMPs are either photo-activated immediately before intravenous injection, or are directly activated on tissue sections. Normal skeletal collagen remolding in nude mice and collagens in prefixed mouse cornea tissue sections are imaged in this procedure. The imaging method based on the CMP-collagen hybridization technology presented here could lead to deeper understanding of the tissue remodeling process, as well as allow development of new diagnostics for diseases associated with high collagen remodeling activity.

Imaging Denatured Collagen Strands In vivo and Ex vivo via Photo-triggered Hybridization of Caged Collagen Mimetic Peptides

This procedure demonstrates in vivo near IR fluorescence imaging of collagen remodeling activities in mice as well as ex vivo staining of collagens in tissue sections using caged collagen mimetic peptides that can be photo-triggered to hybridize with denatured collagen strands.

成像变性的胶原股<em&gt;在体内</em&gt;和<em&gt;体外</em&gt;通过光引发杂交笼胶原蛋白仿生肽

Collagen is a major structural component of the extracellular matrix that supports tissue formation and maintenance. Although collagen remodeling is an ...

Biomechanical Characterization of Human Soft Tissues Using Indentation and Tensile Testing

Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should mimic the human tissues they are aiming to replace; to provide the required anatomical shape, the materials must be able to sustain the mechanical forces they will experience when implanted at the defect site. Although the mechanical properties of tissue-engineered scaffolds are of great importance, many human tissues that undergo restoration with engineered materials have not been fully biomechanically characterized. Several compressive and tensile protocols are reported for evaluating materials, but with large variability it is difficult to compare results between studies. Further complicating the studies is the often destructive nature of mechanical testing. Whilst an understanding of tissue failure is important, it is also important to have knowledge of the elastic and viscoelastic properties under more physiological loading conditions.
This report aims to provide a minimally destructive protocol to evaluate the compressive and tensile properties of human soft tissues. As examples of this technique, the tensile testing of skin and the compressive testing of cartilage are described. These protocols can also be directly applied to synthetic materials to ensure that the mechanical properties are similar to the native tissue. Protocols to assess the mechanical properties of human native tissue will allow a benchmark by which to create suitable tissue-engineered substitutes.

Tissue biomechanics is important for maintaining cell shape and function and for determining phenotype. This report demonstrates non-destructive mechanical protocols for characterizing elastic and viscoelastic properties of human soft tissues, which can be directly applied to tissue-engineered substrates to allow a close matching of engineered materials to native tissue.

人体软组织的生物力学特性采用压痕和拉伸试验

Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should ...

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential to establish an ex vivo model that can evaluate SIM performance accurately, for developing high-performance SIMs. In our previous study, we developed a new ex vivo model that can be used to evaluate the performance of various SIMs in detail by applying constant tension to the specimen&#39;s ends. We also confirmed that the proposed new ex vivo model allows accurate submucosal elevation height (SEH) measurement under uniform conditions and detailed comparisons of the performances of various types of SIMs. Here, we describe the new ex vivo model and explain the detailed setup methodology of this model. Since all parts of the new model were easy to obtain, the setup of the new model could be completed quickly. SEH of various SIMs could be measured more accurately by using the new model. The critical factor that determines SIM performance can be identified using the new model. SIM development speed will drastically increase after the factor has been identified.

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

We developed a new ex vivo model that applies constant tension to the porcine gastric specimen. This development made it possible to evaluate the performance (the height and duration of the submucosal elevation) of various SIMs accurately.&#160; The detailed setup methodology of this new model is explained.

内镜下黏膜下注射材料性能评价的一种新的体内模型

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential ...

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate (LAL) Assays

When present in pharmaceutical products, a Gram-negative bacterial cell wall component endotoxin (often also called lipopolysaccharide) can cause inflammation, fever, hypo- or hypertension, and, in extreme cases, can lead to tissue and organ damage that may become fatal. The amounts of endotoxin in pharmaceutical products, therefore, are strictly regulated. Among the methods available for endotoxin detection and quantification, the Limulus Amoebocyte Lysate (LAL) assay is commonly used worldwide. While any pharmaceutical product can interfere with the LAL assay, nano-formulations represent a particular challenge due to their complexity. The purpose of this paper is to provide a practical guide to researchers inexperienced in estimating endotoxins in engineered nanomaterials and nanoparticle-formulated drugs. Herein, practical recommendations for performing three LAL formats including turbidity, chromogenic and gel-clot assays are discussed. These assays can be used to determine endotoxin contamination in nanotechnology-based drug products, vaccines, and adjuvants.

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate LAL Assays

Detection of endotoxins in engineered nanomaterials represents one of the grand challenges in the field of nanomedicine. Here, we present a case study that describes the framework composed of three different LAL formats to estimate potential endotoxin contamination in nanoparticles.

用利穆鲁布莱巴细胞裂解液 (lal) 法检测纳米配方中的内毒素

When present in pharmaceutical products, a Gram-negative bacterial cell wall component endotoxin (often also called lipopolysaccharide) can cause ...

Methods for In Vivo Biomechanical Testing on Brachial Plexus in Neonatal Piglets

Neonatal brachial plexus palsy (NBPP) is a stretch injury that occurs during the birthing process in nerve complexes located in the neck and shoulder regions, collectively referred to as the brachial plexus (BP). Despite recent advances in obstetrical care, the problem of NBPP continues to be a global health burden with an incidence of 1.5 cases per 1,000 live births. More severe types of this injury can cause permanent paralysis of the arm from the shoulder down. Prevention and treatment of NBPP warrants an understanding of the biomechanical and physiological responses of newborn BP nerves when subjected to stretch. Current knowledge of the newborn BP is extrapolated from adult animal or cadaveric BP tissue instead of in vivo neonatal BP tissue. This study describes an in vivo mechanical testing device and procedure to conduct in vivo biomechanical testing in neonatal piglets. The device consists of a clamp, actuator, load cell, and camera system that apply and monitor in vivo strains and loads until failure. The camera system also allows monitoring of the failure location during rupture. Overall, the presented method allows for a detailed biomechanical characterization of neonatal BP when subjected to stretch.

Methods for In Vivo Biomechanical Testing on Brachial Plexus in Neonatal Piglets

Presented here are methods to perform in vivo biomechanical testing on brachial plexus in a neonatal piglet model.

新生儿小猪体内胸腺菌的活体力学试验方法

Neonatal brachial plexus palsy (NBPP) is a stretch injury that occurs during the birthing process in nerve complexes located in the neck and shoulder ...

Synthesis of Graphene-Hydroxyapatite Nanocomposites for Potential Use in Bone Tissue Engineering

Developing novel materials for bone tissue engineering is one of the most important thrust areas of nanomedicine. Several nanocomposites have been fabricated with hydroxyapatite to facilitate cell adherence, proliferation, and osteogenesis. In this study, hybrid nanocomposites were successfully developed using graphene nanoribbons (GNRs) and nanoparticles of hydroxyapatite (nHAPs), that when employed in bioactive scaffolds may potentially improve bone tissue regeneration. These nanostructures can be biocompatible. Here, two approaches were used for preparing the novel materials. In one approach, a co-functionalization strategy was used where nHAP was synthesized and conjugated to GNRs simultaneously, resulting in nanohybrids of nHAP on GNR surfaces (denoted as nHAP/GNR). High-resolution transmission electron microscopy (HRTEM) confirmed that the nHAP/GNR composite is comprised of slender, thin structures of GNRs (maximum length of 1.8 &#181;m) with discrete patches (150-250 nm) of needle-like nHAP (40-50 nm in length). In the other approach, commercially available nHAP was conjugated with GNRs forming GNR-coated nHAP (denoted as GNR/nHAP) (i.e., with an opposite orientation relative to the nHAP/GNR nanohybrid). The nanohybrid formed using the latter method exhibited nHAP nanospheres with a diameter ranging from 50 nm to 70 nm covered with a network of GNRs on the surface. Energy dispersive spectra, elemental mapping, and Fourier transform infrared (FTIR) spectra confirmed the successful integration of nHAP and GNRs in both nanohybrids. Thermogravimetric analysis (TGA) indicated that the loss at elevated heating temperatures due to the presence of GNRs was 0.5% and 0.98% for GNR/nHAP and nHAP/GNR, respectively. The nHAP-GNR nanohybrids with opposite orientations represent significant materials for use in bioactive scaffolds to potentially promote cellular functions for improving bone tissue engineering applications.

Novel nanocomposites of graphene nanoribbons and hydroxyapatite nanoparticles were prepared using solution-phase synthesis. These hybrids when employed in bioactive scaffolds can exhibit potential applications in tissue engineering and bone regeneration.

石墨烯-羟基磷灰石纳米复合材料的合成在骨组织工程中的潜在应用

Developing novel materials for bone tissue engineering is one of the most important thrust areas of nanomedicine. Several nanocomposites have been ...

洁净室环境的微生物控制和监测策略

Microbial Control and Monitoring Strategies for Cleanroom Environments and Cellular Therapies

A well-validated and holistic program that incorporates robust gowning, cleaning, environmental monitoring, and personnel monitoring measures is critical for minimizing the microbial bioburden in cellular therapy manufacturing suites and the corresponding testing laboratories to ensure that the facilities are operating in a state of control. Ensuring product safety via quality control measures, such as sterility testing, is a regulatory requirement for both minimally manipulated (section 361) and more than minimally manipulated (section 351) human cells, tissues, and cellular and tissue-based products (HCT/Ps). In this video, we provide a stepwise guide for how to develop and incorporate the best aseptic practices for operating in a cleanroom environment, including gowning, cleaning, staging of materials, environmental monitoring, process monitoring, and product sterility testing using direct inoculation, provided by the United States Pharmacopeia (USP&lt;71&gt;) and the National Institutes of Health (NIH) Alternative Sterility Testing Method. This protocol is intended as a reference guide for establishments expected to meet current good tissue practices (cGTP) and current good manufacturing practices (cGMP).

作者聚焦：洁净室环境和细胞疗法的微生物控制和监测策略  

The protocol summarizes the best practices to minimize microbial bioburden in a cleanroom environment and includes strategies such as environmental monitoring, process monitoring, and product sterility testing. It is relevant for manufacturing and testing facilities that are required to meet current good tissue practice standards and current good manufacturing practice standards.

洁净室环境和细胞疗法的微生物控制和监测策略

A well-validated and holistic program that incorporates robust gowning, cleaning, environmental monitoring, and personnel monitoring measures is critical ...