这项工作是由它的力学生物学研究所，新加坡研究卓越中心，一个管理的新加坡国家研究基金会的支持。 MFAC是1122703037. BKKT是支持的力学生物学研究所机构科学，技术和研究（新加坡）和国家研究机构（法国）项目下的多次联合计划的支持。我们感谢丹尼尔HC黄先生的校对书稿和黎明JH新女士协助视频制作。

1.准备聚电解质溶液的<ol><li>纯化脱乙酰壳多糖，如在Liao 等详细说明。简言之，将创建一个1％（重量/体积）壳聚糖在2％的溶液使用（体积/体积）乙酸和真空过滤级93过滤纸。中和使用5M的NaOH将滤液直到pH稳定至7。离心沉淀的脱乙酰壳多糖在1200×g离心10分钟。滗析出上清液，并添加去离子水以洗涤脱乙酰壳多糖。重复离心和洗涤步骤两次以上。冻结的沉淀壳聚糖在-80℃和冷冻干燥O / N以获得纯化形式。存储纯化壳聚糖在除湿柜。 </li><li>称量1g纯壳聚糖进入无菌组织培养皿。放置在组织培养皿尽可能接近到紫外灯在生物安全柜的脱乙酰壳多糖和暴露于UV光15分钟。使用无菌镊子，将灭菌壳聚糖到玻璃容器中。壳聚糖溶解过滤使用0。15M乙酸至0.5％至1％的终浓度（重量/体积）。 </li><li>称取0.1克藻酸的钠盐和溶解在蒸馏水去离子（DDI）的10ml水，得到1％（重量/体积）溶液。混合的藻酸的钠盐，至少2小时，在涡流混合器以确保完全溶解。通过过滤0.2微米的注射器过滤器的海藻酸钠溶液。储存在4℃的藻酸盐溶液。 </li><li>重组人重组生长因子，如血管内皮生长因子（VEGF）或β - 神经生长因子（NGF），如制造商推荐的。 </li></ol> 2.绘图IPC纤维<ol><li>混合蛋白，生长因子或其它生物分子进入电解质溶液具有类似净电荷10-20微升等份。生物分子与净负电荷（例如，牛血清白蛋白〔BSA〕）应与藻酸盐溶液混合。生物分子的净正电荷（如VEGF）应与混合壳聚糖溶液。 </li><li>将壳聚糖和海藻酸钠的小等份（10-20微升）上覆盖有封口膜平坦光滑的表面。脱乙酰壳多糖和藻酸盐的液滴应该放置在接近但不与彼此相接触。 </li><li>轻轻浸每个尖端上的一对镊子进入壳聚糖和藻酸盐的微滴。一起捏钳把聚电解质的液滴。当液滴接触到彼此接触，慢慢地将钳子垂直向上从两个液滴（ 图1A）的接口绘制了IPC纤维。 </li><li>拉伸的IPC纤维上的集电极，所述镊子的末端小心地例如平坦聚合物支架固定在一个旋转的心轴（见第3和4）。旋转心轴以10mm / sec的固定速度以允许形成均匀的和无珠的IPC纤维。增加绘制了IPC的纤维将形成小珠的速度，这将导致结合的爆发释放生化和过早的光纤终端。10 </li><li>为了确定掺入的效率，收集所有的剩余液体留在封口膜通过用500μl1X磷酸盐缓冲盐水（PBS）中稀释。测量通过BCA测定法（对BSA），酶联免疫吸附（对VEGF和NGF）或适当的测定法来检测结合的生物分子中的残基的蛋白质或生长因子含量。 </li></ol> 3.制作普鲁兰多糖葡聚糖复合水凝胶支架（PD）多糖和IPC纤维<ol><li>制造牺牲普鲁兰框架IPC纤维集合<ol><li>称出支链淀粉的多糖并用蒸馏水去离子（DDI）水混合，以创建一个20％（重量/体积）的水溶液。混合普鲁兰多糖溶液O / N，以保证均匀性。 </li><li>投将15克的支链淀粉溶液倒入一个直径10厘米的组织培养聚苯乙烯（TCPS）菜。干普鲁兰多糖溶液O / N在37℃。切普鲁兰多糖薄膜7成毫米×7毫米的方形框架。 </li></ol></li><li>准备普鲁兰葡聚糖多糖溶液<ol><li>创建一个30％（重量/体积）的多糖类的溶液支链淀粉和葡聚糖:在DDI水（3比1的比例）。混合O / N，以确保多糖溶液的均匀性。慢慢在碳酸氢钠添加到多糖溶液以达到20％的终浓度（重量/体积）。混合O / N，以确保溶液的均匀性。储存在4℃的多糖溶液。 </li></ol></li><li>收集普鲁兰框架IPC纤维<ol><li>贴上使用鳄鱼夹牺牲普鲁兰框架（第3.1节）。粘鳄鱼夹和支链淀粉帧上使用塑料涂覆粘合带的转动心轴的末端。旋转与贴帧芯棒以10毫米/秒的恒定速度。普鲁兰多糖架可贴到所希望的方向旋转芯棒。 </li></ol></li><li>用画一双镊子（第1节）和ATTAC的IPC纤维小时IPC纤维的结束画上旋转普鲁兰框架。绘制了IPC纤维以恒定的速度。一旦到达了IPC纤维的末端，干燥纤维上帧构建O / N在室温。 </li><li> IPC嵌入纤维进入PD水凝胶支架</li><li>以交联每克支链淀粉葡聚糖溶液中，添加11％的100微升（重量/体积）三偏磷酸钠水溶液和氢氧化钠将100μl10M钠7使用stirplate为1至2分钟，混合溶液在60rpm。添加的三偏磷酸钠和氢氧化钠之后，将多糖溶液将几乎立即交联。倾粘性多糖溶液到纤维上帧构造完全嵌入的IPC纤维。孵育结合支链淀粉葡聚糖的IPC纤维（PD-IPC），在60℃进行30分钟，形成化学交联的复合支架（ 图1B）。 </li><li>注意:在通风柜执行步骤3.3.2，并使用适当的保护相等pment乙酸是腐蚀性和易燃。 </li><li>为了诱导孔形成在PD-IPC脚手架，淹没整个支架在20％（重量/体积）乙酸20分钟。 </li><li>为5分钟，在1×PBS中洗涤的PD-IPC支架除去未反应的试剂以100rpm摇动。重复此步骤2次。 </li><li>除去多余的PBS，并立即冻结PD-IPC支架在-80°CO / N。冻干支架的任何控制释放生物活性或使用试验前至少24小时。 </li></ol> 4.制作PCL和IPC纤维复合支架注意:二氯甲烷是一种有害物质。二氯甲烷处理时，使用通风橱和个人防护装备。 <ol><li>创建原始和图案的PDMS基板<ol><li>创建一个纯净的聚二甲基硅氧烷（PDMS）的弹性基板采用了一块所需尺寸的TCPS使用软光刻工艺。创建patterned的PDMS衬底 ​​通过使用标准软光刻方法对聚（甲基丙烯酸甲酯）与所需的形貌的模板。12 </li></ol></li><li>制造牺牲PCL框架IPC纤维集合<ol><li>称取PCL和溶解在二氯甲烷中以创建一个0.9％（重量/体积）溶液。每1 平方厘米面积的PDMS衬底 ​​的，滴加入500μl的0.9％的PCL溶液。允许所有的二氯甲烷溶剂完全蒸发，在通风橱。重复铸造0.9％PCL到薄膜变厚至期望的厚度的过程。从PDMS基板取下干燥PCL电影。创建在使用适宜尺寸的冲床在PCL帧的孔。2 </li></ol></li><li>在PCL框架上收集IPC纤维<ol><li>上贴上鳄鱼夹与孔（从4.2.1）牺牲PCL框架。通过使用塑料涂层胶带粘鳄鱼夹到旋转心轴。附加IPC纤维的结束画上PCL FRAM开始旋转，速度为10mm /秒（第2节）以恒定的速度前即IPC纤维拉伸结束后，干燥纤维上的帧构建O / N在4℃。 </li></ol></li><li>嵌入光纤的框架构建成图案PCL基板<ol><li>降500微升0.9％PCL解决方案到PDMS基板打造一个纯净的或有图案的PCL基地，根据需要。施放的0.9％的PCL溶液多层以获得具有所需厚度的脚手架。允许所有的二氯甲烷溶剂完全蒸发，在通风橱。 </li><li>放置在纤维上的帧结构（第4.3.1节）在PCL基座的顶部。加在纤维上帧构造多次0.9％的PCL溶液，以获得所需的厚度和完全嵌入的IPC纤维，制造的PCL-IPC复合支架（ 图1C）。 </li></ol></li></ol> 5.测量生物制剂的释放从复合IPC支架<ol><li>将复合PD-IPC或PCL-IPC支架和单机IPC纤维分别在24孔板。 </li><li>沉浸脚手架和单机IPC纤维用500μl1X PBS的。孵育样品在37℃。收集的PBS在不同时间点（释放介质）和替换用500μl1X PBS中。 </li><li>测量在使用BCA测定法（BSA），酶联免疫吸附（VEGF和NGF）或其他适当的测定法来计算掺入的生物分子的累积释放曲线的释放介质蛋白或生长因子的量。 </li></ol>复合IPC支架6.种子细胞来测试释放生物制剂的生物活性<ol><li>消毒使用UV光在生物安全柜为至少20分钟的冷冻干燥的PD-IPC或PCL-IPC复合支架。 </li><li>使用标准的细胞培养技术，以获得在200μl生长培养基2×10 5个细胞的细胞悬浮液。种子的浓缩细胞悬浮液上的复合支架。 AFTER 20分钟，生长培养基补足体积至完全淹没支架。 </li><li>通过测量如Alamar蓝代谢活性测定，PC12轴突生长法或免疫荧光技术标准的细胞活性。 </li></ol>

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J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+poly(ethylene+glycol)+hydrogel+microstructures+using+photolithography.">Fabrication of poly(ethylene glycol) hydrogel microstructures using photolithography.</a> Langmuir. 17 (18), 5440-5447 (2001).</li><li>Yim, E. K. F., Liao, I. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+compatibility+of+interfacial+polyelectrolyte+complexation+fibrous+scaffold:+evaluation+of+blood+compatibility+and+biocompatibility.">Tissue compatibility of interfacial polyelectrolyte complexation fibrous scaffold: evaluation of blood compatibility and biocompatibility.</a> Tissue Eng. Part A. 13 (2), 423-433 (2007).</li><li>Chaouat, M., Le Visage, C., Autissier, A., Chaubet, F., Letourneur, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+evaluation+of+a+small-diameter+polysaccharide-based+arterial+graft+in+rats.">The evaluation of a small-diameter polysaccharide-based arterial graft in rats.</a> Biomaterials. 27, 5546-5553 (2006).</li><li>Eshraghi, S., Das, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+and+microstructural+properties+of+polycaprolactone+scaffolds+with+one-dimensional,+two+dimensional,+and+three-dimensional+orthogonally+oriented+porous+architectures+produced+by+selective+laser+sintering.">Mechanical and microstructural properties of polycaprolactone scaffolds with one-dimensional, two dimensional, and three-dimensional orthogonally oriented porous architectures produced by selective laser sintering.</a> Acta Biomater. 6, 2467-2476 (2010).</li></ol>

The authors have nothing to disclose.

IPC纤维通过两个带相反电荷的聚电解质的相互作用形成。该方法使用从聚电解质的界面的复杂的提取，便利了一种用于纤维形成稳定的自组装过程。 IPC的纤维形成的机制可确保任何生物分子加入到类似电荷的聚电解质可以在络合过程中引入。10,11相反，除了生物分子的成带相反电荷的聚电解质将导致瞬间沉淀。用于IPC纤维的简单的制造方法借给多功能性在将各种生物材料如细胞，生长因子和小分子。还观察到在两个对PD-IPC和PCL-IPC复合支架，其中的生长因子具有不同的物理和生物分子性质（电荷及分子量）掺入具有高效率的IPC纤维的这一关键特征。在禁忌省，使用微球的方法对VEGF和NGF包封率可以低至16％的6和8％13。 这两个PD-IPC和PCL-IPC支架也表现出生物分子的释放时间控制。从PD-IPC支架血管内皮生长因子呈线性释放至少7天。与此相反，报告从聚合物微球的VEGF的释放曲线显示在24小时内的初始突发释放，释放的总的VEGF含量为至少60％。5,14,15同样，神经生长因子被证明从PCL-IPC持续生长因子递送支架，而其它聚合物为基础的增长因子递送系统显示释放的20天释放的平台期。13,16据推测，所述复合支架的不同部件都有助于生长因子释放动力学。聚合物松弛机制，孔隙度和弯曲度可以极大地影响亲水生物分子的释放。17此外，的C所述聚合骨架的hemical特征可以具有静电吸引和排斥向影响生物分子释放的生长因子。因此，该聚合骨架的特点是在确定释放曲线和生物分子以时间上控制释放是至关重要的。例如，当对PD支架呈接近线性的BSA的释放，类似的复合支架使用聚（乙烯醇）水凝胶缺乏渗透性与BSA 18聚合物支架可结合使用IPC纤维可能需要初步试验以确定其渗透性范围。 除了控制生化释放，以保持生长因子的生物活性的能力为任何生物分子递送系统的一个重要特征。对PD溶液的苛刻的碱性环境和有机DCM溶剂中的PCL存在下具有降解任何种类的生物分子的潜力。例如，微球递送system所使用二氯甲烷表现出与增加的时间点，由于NGF的降解减少生物活性的趋势一致。16然而，我们观察到血管内皮生长因子和生长因子的生物活性被保持，进一步重申的IPC纤维的一个重要优势是内复合同化支架。 使用牺牲的，生物相容的多糖或聚合物框架可以容易地并入到散装支架给出的多功能性以创建复合支架具有多个IPC纤维在不同的配置排列。7。因此，要被施加的聚合物支架，有必要与IPC纤维具有进一步同化能力成批量支架。同化过程是完全嵌入IPC纤维进入聚合骨架重要。我们在该牺牲支链淀粉和PCL帧，这是既易于溶解在散装PD的溶剂或观察到这种现象PCL支架。此外，对于IPC的制造和生物分子结合的单步方法提供了灵活性，以能够由单个复合支架递送生物分子的数量。该方法的简单性也允许微调掺入效率和释放的动力学通过改变聚电解质身份或浓度。天然聚电解质壳聚糖和藻酸盐中，由于使用其高电荷密度和相似于动物组织中发现的各种细胞外基质的碳水化合物。然而甲基化胶原和三元共聚物8,19或壳多糖和藻酸盐20还可以用于IPC的纤维形成不同的效果。多的IPC纤维释放不同的生化线索具有不同动力学也可以实现以创建一个多功能复合支架。例如，细胞外基质蛋白，如纤连蛋白加载到IPC纤维可以用于空间控制细胞粘着提供了一个平台。7持续抗生素和生长因子的释放也是理想的组织再生应用程序。这可能通过使用PCL-IPC，其可以掺入疏水性的，小分子药物，并在复合支架的不同区室的亲水性，基于蛋白质的生长因子。2 我们提出的方法也允许与两个地形和生化线索的支架的制造。我们观察到的NP-PCL-IPC支架具有最高的增强的hMSC分化成神经元谱系，这意味着模仿生物物理和生物化学细胞小生的多个方面是有益的指导细胞行为。所提出的方法的便利性使得其应用到其它形成图案的聚合物体系，如聚丙烯酰胺21或聚乙二醇22，其前提是在交联过程中不会显著影响的IPC纤维完整性。例如，PD支架是CHOSEN在这项研究中以其独特的交联机制，发生在环境温度和含水条件24这可以潜在地提供更多的生理学相关底物的体外和体内研究。此外，在一个复合支架嵌入的IPC纤维可以通过提供拉伸强度克服缺乏IPC纤维23的机械强度。的确，PCL 25被选定为它的高机械强度。 总之，用于创建复合支架用于生物分子递送的简单方法进行了说明。我们展示了纤维如何IPC可以用于持续递送生物分子的，而不损害其生物活性和掺入效率。 PD-IPC和PCL-IPC支架:我们通过两种形式创建复合支架表现出这一点。 IPC纤维的适用性不限于掺入PD-和PCL基于支架，但也可以潜在地扩展到其他聚合物体系并提供其它生物分子。

The extracellular matrix has inherent biochemical and biophysical cues that direct cell behaviors. Mimicking this physiological three-dimensional (3D) microenvironment is a widely explored strategy for regenerative medicine and tissue engineering applications. For example, both naturally-derived and synthetic substrates have been modified with topographical cues as a means to mimic the biophysical cellular environment.1 For example, polycaprolactone (PCL) scaffolds can be easily patterned by casting on patterned PDMS substrates.2 However, most synthetic scaffolds inadequately recapitulate the controlled biochemical environment in vivo. Bulk or surface modification of synthetic materials only present biochemical cues for cell attachment but still lack temporal regulation of biochemical delivery.3 Thus, there is a need for optimal scaffolds that can mimic the temporally regulated biochemical delivery system of the extracellular matrix. 
Biochemical delivery systems such as microspheres are plagued by problems of loss of bioactivity and low incorporation efficiency due to the severity and complexity of multi-step synthesis process.4-6 Alternative methods that use a one-step fabrication and incorporation method were proven to have excellent potential to create a favorable biochemical microenvironment without the accompanying inefficiency in incorporation and loss of bioactivity. One viable solution is the use of interfacial polyelectrolyte complexation (IPC) fibers to deliver and protect biological agents. When two oppositely charged polyelectrolyte aqueous solutions are brought together, IPC fibers can be drawn out from the interface. Virtually any type of hydrophlic biomolecule in aqueous solution can be added into either the negatively- or positively-charged polyelectrolyte solution, thus facilitating the incorporation of useful biomolecules into the IPC fiber during the complexation process. Furthermore, this process only requires aqueous and ambient conditions, thereby decreasing the risk of loss of bioactivity. Using this method, active growth factors2,7 even cells8,9 have been successfully delivered. In addition, the simple method of forming IPC fibers allows molding into any shape or orientation. The stability of such fibers has been advantageous in its incorporation into both hydrophobic2 and hydrophilic polymers7 to create composite scaffolds. These composite scaffolds with IPC fibers are beneficial for creating a physiologically relevant biochemical environment while providing physical anchorage for cells. 
In this study, we show a method to incorporate IPC fibers into a hydrophilic and a hydrophobic scaffold with topography for controlled release of active biomolecules. As a proof-of-concept, we incorporate IPC fibers made from chitosan and alginate into the biocompatible, non-immunogenic and non-antigenic pullulan-dextran hydrophilic hydrogel or the biocompatible polycaprolactone hydrophobic scaffold.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Pullulan&#160;</td>
			<td>Hayashibara Inc Okayama Japan</td>
			<td></td>
			<td>Molecular weight (MW) 200 kDa. This material is pharmaceutical grade pullulan used to make pullulan frames and PD-IPC scaffolds.</td>
		</tr>
		<tr>
			<td>Dextran</td>
			<td>Sigma Aldrich</td>
			<td>D1037</td>
			<td>MW 500 kDa. This material is no longer being produced by Sigma Aldrich. Alternative suggested is catalog number 31392 (Sigma Aldrich). This material is used to make PD-IPC scaffolds.</td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate&#160;</td>
			<td>Sigma Aldrich</td>
			<td>S5761</td>
			<td>Sodium bicarbonate must be slowly added to the pullulan-dextran polysaccharide solution. Rapid addition of sodium bicarbonate will result in precipitation.&#160;</td>
		</tr>
		<tr>
			<td>Sodium Trimetaphosphate</td>
			<td>Sigma Aldrich</td>
			<td>T5508</td>
			<td>This chemical is hygroscopic and must be stored in the dehumidifying cabinet. Aqueous solution of sodium trimetaphosphate must always be made fresh.</td>
		</tr>
		<tr>
			<td>Sodium Hydroxide</td>
			<td>Sigma Aldrich</td>
			<td>S5881</td>
			<td>This material is hazardous and must be handled with proper protective equipment such as nitrile gloves.</td>
		</tr>
		<tr>
			<td>Chitosan</td>
			<td>Sigma Aldrich</td>
			<td>448877</td>
			<td>MW 190-310 kDa. Acetylation degree of 75 to 85%. Purification of chitosan is required to create stable IPC fibers.</td>
		</tr>
		<tr>
			<td>Acetic Acid</td>
			<td>Merck</td>
			<td></td>
			<td>This can be replaced by another brand type. This material is corrosive and flammable. Protective equipment such as face shield, nitrile gloves, lab coat and shoe cover must be worn when handling this chemical in the fume hood.&#160;</td>
		</tr>
		<tr>
			<td>Alginic acid sodium salt from brown algae, low viscosity</td>
			<td>Sigma Aldrich</td>
			<td>A2158</td>
			<td>Dissolve in water overnight. Filter through sterile 0.2&#181;m syringe filter before use. Store at 4 &#176;C.</td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sinopharm Chemical Reagent</td>
			<td></td>
			<td>Dissolve in sterile PBS and filter using 0.2 &#181;m syringe filter before use.&#160;</td>
		</tr>
		<tr>
			<td>BCA assay kit</td>
			<td>Pierce</td>
			<td>23225</td>
			<td>This kit was used to measure BSA release from PD-IPC scaffolds.&#160;</td>
		</tr>
		<tr>
			<td>Human Recombinant Vascular Endothelial Growth Factor</td>
			<td>R&#38;D systems</td>
			<td>293-VE</td>
			<td>Dissolve growth factor in 0.2% heparin solution to a final concentration of 5 mg/ml.</td>
		</tr>
		<tr>
			<td>Heparin Sodium Salt From Porcine</td>
			<td>Sigma Aldrich</td>
			<td>H3393</td>
			<td>This can be replaced by another brand type. Dissolve heparin salt in sterile water at a final concentration of 1% and filter through 0.2 &#181;m syringe filter before use.&#160;</td>
		</tr>
		<tr>
			<td>Human Umbilical Vein Endothelial Cells (HUVEC)</td>
			<td>Lonza</td>
			<td>C2517A</td>
			<td>This primary cell type was used in the assay to determine VEGF bioactivity after release from PD-IPC scaffolds.&#160;</td>
		</tr>
		<tr>
			<td>Alamar blue</td>
			<td>Life Technologies</td>
			<td>DAL1025</td>
			<td>This is used to measure cell metabolic activity. Incubate Alamar blue with cells and maintain in standard cell culture conditions for 2 to 4 hours. Measure absorbance at 570 nm to determine Alamar blue percent reduction, which is correlated to the cell activity.&#160;</td>
		</tr>
		<tr>
			<td>ScanVac Coolsafe Lyophilizer</td>
			<td>Labogene</td>
			<td>7.001.200.060</td>
			<td>This is a non-programmable freeze dryer that operates at -105 to -110 &#176;C, This can be replaced by other standard lab lyophilizers.</td>
		</tr>
		<tr>
			<td>Polycaprolactone (PCL)</td>
			<td>Sigma Aldrich</td>
			<td>181609</td>
			<td>MW 65 kDa. This is no longer being manufactured by Sigma Aldrich. This can be replaced by Sigma Aldrich catalog number 704105.</td>
		</tr>
		<tr>
			<td>Dichloromethane</td>
			<td>Sigma Aldrich</td>
			<td>V800151</td>
			<td>This can be replaced by another brand type. This material is hazardous and must be handled in the fume hood. Protective equipment must be worn at all times when handling this chemical.</td>
		</tr>
		<tr>
			<td>Polydimethylsiloxane (PDMS; 184 Silicone Elastomer Kit)</td>
			<td>Dow Corning</td>
			<td>(240)4019862</td>
			<td>The elastomer kit comes with polymer base and crosslinker. Mixing the polymer base and crosslinker in different ratios will result in different stiffness of the PDMS.</td>
		</tr>
		<tr>
			<td>Human Recombinant Beta-Nerve Growth Factor (NGF)</td>
			<td>R&#38;D systems</td>
			<td>256-GF</td>
			<td>Reconstituted in sterile DI water to a final concentration of 100 &#181;g/ml. Aliquot and store in -20 &#176;C until use.</td>
		</tr>
		<tr>
			<td>Human Mesenchymal Stem Cells (hMSC)</td>
			<td>Cambrex</td>
			<td></td>
			<td>This cell type was used in the assay to determine synergistic effect of NGF and nanotopography.</td>
		</tr>
		<tr>
			<td>Rat PC12 Pheochromocytoma Cells&#160;</td>
			<td>ATCC</td>
			<td></td>
			<td>This cell type was used in the neurite outgrowth assay to determine bioactivity of NGF. After exposure to release media with NGF, measure number of cells with neurite extensions and normalize to total number of cells.</td>
		</tr>
		<tr>
			<td>Grade 93 filter paper</td>
			<td>Whatman</td>
			<td>Z699675</td>
			<td>This is used for the purification of chitosan after its precipitation with sodium hydroxide at pH 7.</td>
		</tr>
		<tr>
			<td>Swing bucket centrifuge</td>
			<td>Eppendorf</td>
			<td>5810R</td>
			<td>To be used during the purification of chitosan using 1200 x g speed.&#160;</td>
		</tr>
		<tr>
			<td>Motor with mandrel rotating at constant speed</td>
			<td>Rhymebus</td>
			<td>RM5E</td>
			<td>The motor is used for the fabrication of IPC fibers on pullulan or PCL frame.</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline</td>
			<td>FirstBase</td>
			<td></td>
			<td>Sterilize through filtration (0.2 &#181;m filter) and autoclave.&#160;</td>
		</tr>
		<tr>
			<td>10-mm diameter Tissue Culture Polystyrene Dish (TCPS)</td>
			<td>Greiner</td>
			<td></td>
			<td>The TCPS dish is used for casting of pullulan frame.&#160;</td>
		</tr>
		<tr>
			<td>Human VEGF ELISA kit</td>
			<td>R&#38;D systems</td>
			<td>DVE00</td>
			<td>The ELISA kit is used for detection of VEGF in the release medium.</td>
		</tr>
		<tr>
			<td>Human NGF ELISA kit</td>
			<td>R&#38;D systems</td>
			<td>DY256</td>
			<td>&#160;The ELISA kit is used for detection of NGF in the release medium.</td>
		</tr>
		<tr>
			<td>Plastic Coated Adhesive Tape</td>
			<td>Bel-Art</td>
			<td>9040336</td>
			<td>The adhesive tape is used to securely stick the alligator clip to the rotating mandrel</td>
		</tr>
	</tbody>
</table>

composite scaffolds of interfacial polyelectrolyte fibers for temporally controlled release of biomolecules

Various scaffolds used in tissue engineering require a controlled biochemical environment to mimic the physiological cell niche. Interfacial polyelectrolyte complexation (IPC) fibers can be used for controlled delivery of various biological agents such as small molecule drugs, cells, proteins and growth factors. The simplicity of the methodology in making IPC fibers gives flexibility in its application for controlled biomolecule delivery. Here, we describe a method of incorporating IPC fibers into two different polymeric scaffolds, hydrophilic polysaccharide and hydrophobic polycaprolactone, to create a multi-component composite scaffold. We showed that IPC fibers can be easily embedded into these polymeric structures, enhancing the capability for sustained release and improved preservation of biomolecules. We also created a composite polymeric scaffold with topographical cues and sustained biochemical release that can have synergistic effects on cell behavior. Composite polymeric scaffolds with IPC fibers represent a novel and simple method of recreating the cellular niche.

在这篇文章中，我们试图建立复合支架与IPC纤维各种生物分子的持续释放。在此研究中使用的生物分子的特征见于表1。的IPC纤维第一嵌入到亲水的PD水凝胶来创建的PD-IPC复合支架（ 图1B）。模型分子BSA的第一测试，以确定使用复合支架用于控制生物分子释放的可行性。 BSA的掺入的PD-IPC支架为45±0.97％的效率。 BSA的从PD-瞳距释放呈接近线性的动力学具有初始减毒突释之后是伴随稳态（ 图2）。 2个月后，BSA达到97％的总释放。相反，独立的IPC纤维显示出4小时内的80％的BSA的快速释放。 接着，我们检查VEGF的释放曲线和生物活性使用的PD-IPC scaffoLDS。血管内皮生长因子中掺入的75.5±2.7％的效率，并呈持续释放至少1周（ 图3A）。人脐静脉内皮细胞（HUVEC）接种在PD-IPC支架，以确定VEGF的生物活性。血管内皮细胞上的PD-IPC显示支架与普通支架的PD在第1天相比显著增加Alamar蓝和降低代谢活动，表示从PD-IPC支架（ 图3B）被释放后，保存好血管内皮生长因子的功能。阿尔玛蓝在减少3天，第6和第7下降到达到相当水平与普通支架PD（ 图3B）。 在PCL-IPC复合支架还测试控释并与独立的IPC纤维相比。我们结合NGF为代表的分子进入PCL-IPC复合支架与66.38±2.71％的掺入效率。 PCL-IPC复合支架呈线芳缓释和18天后（ 图4A）约80％的累积释放。另一方面，IPC单机纤维显示在24小时内，随后通过一个停滞释放速率的70％的爆发释放。使用的PC12神经突增生测定中，我们检查了释放的NGF（ 图4B）的生物活性。上生长的PCL-IPC复合支架释放介质PC12细胞的神经突增生显示出相似水平与PC12细胞在30毫微克培养/ ml的神经生长因子补充培养基。这表明NGF释放生物活性保持至少7天。 地形的组合和持续的生长因子交货可能模仿了细胞微环境更好。 PCL的-IPC制造的多功能方法允许biochemically-和地形控制的复合支架的制造。我们制作了PCL-IPC复合支架具有纳米尺寸结构光栅（NP-PCL-IPC支架）。我们观察到的协同EF地形FECT和持续的NGF释放通过评估人类间质干细胞（hMSC）的培养（ 图5）的神经元分化。的hMSCs的NP-PCL-IPC复合支架培养表现出较高的表达微管相关蛋白2（MAP2）的，表示神经元的分化。另一方面，MAP2蛋白表达中的hMSCs只有NGF释放或图案化的PCL（NP-PCL）对PCL-IPC培养低得多。 <img alt="图1" src="/files/ftp_upload/53079/53079fig1.jpg" /> 图1. IPC掺入到纤维的亲水性和疏水性支架。IPC纤维（A）水彩在正（壳聚糖）的接口和负（海藻酸钠）电荷的聚电解质溶液。 （B）中示出在亲水性的PD溶液的IPC纤维掺入到创建的PD-IPC组合大示意图<html> Ë脚手架。显示疏水PCL支架IPC纤维的结合（C）示意图创建PCL-IPC复合支架。这个数字是改编自Cutiongco 等人 ，2014年7 <a href="https://www.jove.com/files/ftp_upload/53079/53079fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" src="/files/ftp_upload/53079/53079fig2.jpg" /> BSA的从PD-IPC复合支架。BSA的图2的控制释放被并入的PD-IPC复合支架，并使用BCA测定其释放，测定在不同时间点。释放累积的BSA被提供作为BSA（以μg）的在IPC纤维掺入的总量的百分比，并表示为平均值百分比±标准偏差。这个数字是改编自Cutiongco 等人 ，2014年7/www.jove.com/files/ftp_upload/53079/53079fig2large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 <img alt="图3" src="/files/ftp_upload/53079/53079fig3.jpg" /> 图3.控释和从PD-IPC复合支架的生物活性的VEGF。（A）中的VEGF从PD-IPC复合支架的累积释放曲线。血管内皮生长因子的释放，测定在使用ELISA特异于VEGF的不同的时间点。上生长的PD-IPC复合支架，如通过Alamar蓝代谢试验测定内皮细胞（B）的细胞存活率。使用单向ANOVA与Tukey的事后检验进行统计分析。 *表示P &lt;0.05。这个数字是改编自Cutiongco 等人 ，2014年7 <a href="https://www.jove.com/files/ftp_upload/53079/53079fig3large.jpg" target="_blank">请点击此处查看大图</a><html>这个数字。 <img alt="图4" src="/files/ftp_upload/53079/53079fig4.jpg" /> 图4.控制释放和从PCL-IPC复合支架的生物活性神经生长因子。（A）的 NGF的从PCL-IPC复合支架的累积释放曲线。神经生长因子释放测定在使用ELISA特异于NGF的不同的时间点。插图显示NGF的从PCL-IPC支架的前8小时的累积释放曲线。 NGF（二）生物活性由PC12神经细胞生长测量。 PC12增生是通过图像分析测量。这个数字是改编自张志贤等人 ，2014年2 <a href="https://www.jove.com/files/ftp_upload/53079/53079fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> .JPG"/&gt; 图上的NP-PCL-IPC支架5.分化的hMSC，hMSC的共焦扫描显微镜图像培养在不同的复合支架。 （A）NP-PCL-IPC，（B）NP-PCL，（C）PCL-IPC，（D）精粹PCL支架。绿色染色表示MAP2，神经元谱系标记。红染色表示F-肌动蛋白，表现出细胞骨架。蓝染色表示细胞核。这个数字是改编自张志贤等人 ，2014年2 <a href="https://www.jove.com/files/ftp_upload/53079/53079fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 生化表1.特性用于控释由复合IPC支架。

Watch this Scientific Journal Video about Composite Scaffolds of Interfacial Polyelectrolyte Fibers for Temporally Controlled Release of Biomolecules at JoVE.com

Composite Scaffolds of Interfacial Polyelectrolyte Fibers for Temporally Controlled Release of Biomolecules

Scaffolds for tissue engineering need to recapitulate the complex biochemical and biophysical microenvironment of the cellular niche. Here, we show the use of interfacial polyelectrolyte complexation fibers as a platform to create composite, multi-component polymeric scaffolds with sustained biochemical release.

界面聚电解质纤维的生物分子在时间控释复合支架

Various scaffolds used in tissue engineering require a controlled biochemical environment to mimic the physiological cell niche. Interfacial ...

composite-scaffolds-interfacial-polyelectrolyte-fibers-for-temporally

Nanyang Technological University

Research

JoVE Journal

Bioengineering

8.3K 次观看.  National University of Singapore. Scaffolds for tissue engineering need to recapitulate the complex biochemical and biophysical microenvironment of the cellular niche. Here, we show the use of interfacial polyelectrolyte complexation fibers as a platform to create composite, multi-component polymeric scaffolds with sustained biochemical release.

视频: Composite Scaffolds of Interfacial Polyelectrolyte Fibers for Temporally Controlled Release of Biomolecules

Elastomeric PGS Scaffolds in Arterial Tissue Engineering

Cardiovascular disease is one of the leading cause of mortality in the US and especially, coronary artery disease increases with an aging population and increasing obesity1. Currently, bypass surgery using autologous vessels, allografts, and synthetic grafts are known as a commonly used for arterial substitutes2. However, these grafts have limited applications when an inner diameter of arteries is less than 6 mm due to low availability, thrombotic complications, compliance mismatch, and late intimal hyperplasia3,4. To overcome these limitations, tissue engineering has been successfully applied as a promising alternative to develop small-diameter arterial constructs that are nonthrombogenic, robust, and compliant. Several previous studies have developed small-diameter arterial constructs with tri-lamellar structure, excellent mechanical properties and burst pressure comparable to native arteries5,6. While high tensile strength and burst pressure by increasing collagen production from a rigid material or cell sheet scaffold, these constructs still had low elastin production and compliance, which is a major problem to cause graft failure after implantation. Considering these issues, we hypothesized that an elastometric biomaterial combined with mechanical conditioning would provide elasticity and conduct mechanical signals more efficiently to vascular cells, which increase extracellular matrix production and support cellular orientation.
The objective of this report is to introduce a fabrication technique of porous tubular scaffolds and a dynamic mechanical conditioning for applying them to arterial tissue engineering. We used a biodegradable elastomer, poly (glycerol sebacate) (PGS)7 for fabricating porous tubular scaffolds from the salt fusion method. Adult primary baboon smooth muscle cells (SMCs) were seeded on the lumen of scaffolds, which cultured in our designed pulsatile flow bioreactor for 3 weeks. PGS scaffolds had consistent thickness and randomly distributed macro- and micro-pores. Mechanical conditioning from pulsatile flow bioreactor supported SMC orientation and enhanced ECM production in scaffolds. These results suggest that elastomeric scaffolds and mechanical conditioning of bioreactor culture may be a promising method for arterial tissue engineering.

Elastomeric PGS scaffolds with vascular smooth muscle cells cultured in a pulsatile flow bioreactor may lead to promising small-diameter arterial constructs with native ECM production in a relatively short culture period.

弹性PGS的动脉组织工程支架

Cardiovascular disease is one of the leading cause of mortality in the US and especially, coronary artery disease increases with an aging population and ...

科研

生物工程

Preparation of 3D Fibrin Scaffolds for Stem Cell Culture Applications

Stem cells are found in naturally occurring 3D microenvironments in vivo, which are often referred to as the stem cell niche 1. Culturing stem cells inside of 3D biomaterial scaffolds provides a way to accurately mimic these microenvironments, providing an advantage over traditional 2D culture methods using polystyrene as well as a method for engineering replacement tissues 2. While 2D tissue culture polystrene has been used for the majority of cell culture experiments, 3D biomaterial scaffolds can more closely replicate the microenvironments found in vivo by enabling more accurate establishment of cell polarity in the environment and possessing biochemical and mechanical properties similar to soft tissue.3 A variety of naturally derived and synthetic biomaterial scaffolds have been investigated as 3D environments for supporting stem cell growth. While synthetic scaffolds can be synthesized to have a greater range of mechanical and chemical properties and often have greater reproducibility, natural biomaterials are often composed of proteins and polysaccharides found in the extracelluar matrix and as a result contain binding sites for cell adhesion and readily support cell culture. Fibrin scaffolds, produced by polymerizing the protein fibrinogen obtained from plasma, have been widely investigated for a variety of tissue engineering applications both in vitro and in vivo 4. Such scaffolds can be modified using a variety of methods to incorporate controlled release systems for delivering therapeutic factors 5. Previous work has shown that such scaffolds can be used to successfully culture embryonic stem cells and this scaffold-based culture system can be used to screen the effects of various growth factors on the differentiation of the stem cells seeded inside 6,7.
 This protocol details the process of polymerizing fibrin scaffolds from fibrinogen solutions using the enzymatic activity of thrombin. The process takes 2 days to complete, including an overnight dialysis step for the fibrinogen solution to remove citrates that inhibit polymerization. These detailed methods rely on fibrinogen concentrations determined to be optimal for embryonic and induced pluripotent stem cell culture. Other groups have further investigated fibrin scaffolds for a wide range of cell types and applications - demonstrating the versatility of this approach 8-12.

This work details the preparation of 3D fibrin scaffolds for culturing and differentiating plutipotent stem cells. Such scaffolds can be used to screen the effects of various biological compounds on stem cell behavior as well as modified to contain drug delivery systems.

制备纤维蛋白三维支架干细胞培养应用

Stem cells are found in naturally occurring 3D microenvironments in vivo, which are often referred to as the stem cell niche 1. Culturing stem cells ...

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, currently available routine methods require processing steps and alter sample integrity. Raman spectroscopy is a fast method that enables the measurement of biological samples without the need for further processing steps. This laser-based technology detects the inelastic scattering of monochromatic light.6 As every chemical vibration is assigned to a specific Raman band (wavenumber in cm-1), each biological sample features a typical spectral pattern due to their inherent biochemical composition.7-9 Within Raman spectra, the peak intensities correlate with the amount of the present molecular bonds.1 Similarities and differences of the spectral data sets can be detected by employing a multivariate analysis (e.g. principal component analysis (PCA)).10
Here, we perform Raman spectroscopy of living cells and native tissues. Cells are either seeded on glass bottom dishes or kept in suspension under normal cell culture conditions (37 &deg;C, 5% CO2) before measurement. Native tissues are dissected and stored in phosphate buffered saline (PBS) at 4 &deg;C prior measurements. Depending on our experimental set up, we then either focused on the cell nucleus or extracellular matrix (ECM) proteins such as elastin and collagen. For all studies, a minimum of 30 cells or 30 random points of interest within the ECM are measured. Data processing steps included background subtraction and normalization.

Raman spectroscopy is a suitable technique for the non-contact, label-free analysis of living cells, tissue-engineered constructs and native tissues. Source-specific spectral fingerprints can be generated and analyzed using multivariate analysis.

非接触，无标签使用拉曼光谱研究细胞和细胞外基质的监测

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, ...

Self-reporting Scaffolds for 3-Dimensional Cell Culture

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting 3D cellular construct can often be more relevant to studying the molecular events and cell-cell interactions than similar experiments studied in 2D. To create effective 3D cultures with high cell viability throughout the scaffold the culture conditions such as oxygen and pH need to be carefully controlled as gradients in analyte concentration can exist throughout the 3D construct. Here we describe the methods of preparing biocompatible pH responsive sol-gel nanosensors and their incorporation into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds along with their subsequent preparation for the culture of mammalian cells. The pH responsive scaffolds can be used as tools to determine microenvironmental pH within a 3D cellular construct. Furthermore, we detail the delivery of pH responsive nanosensors to the intracellular environment of mammalian cells whose growth was supported by electrospun PLGA scaffolds. The cytoplasmic location of the pH responsive nanosensors can be utilized to monitor intracellular pH (pHi) during ongoing experimentation.

Biocompatible pH responsive sol-gel nanosensors can be incorporated into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds. The produced self-reporting scaffolds can be used for in&#160;situ monitoring of microenvironmental conditions whilst culturing cells upon the scaffold. This is beneficial as the 3D cellular construct can be monitored in real-time without disturbing the experiment.

自我报告的支架3维细胞培养

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting ...

Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose and short sisal fibers are dispersed into a water suspension containing bacterial cellulose. The fiber and nanocellulose suspension is then filtered (using vacuum or gravity) and the wet filter cake pressed to squeeze out any excess water, followed by a drying step. This will result in the hornification of the bacterial cellulose network, holding the loose natural fibers together.
Our method is specially suited for the manufacturing of rigid and robust preforms of hydrophilic fibers. The porous and hydrophilic nature of such fibers results in significant water uptake, drawing in the bacterial cellulose dispersed in the suspension. The bacterial cellulose will then be filtered against the surface of these fibers, forming a bacterial cellulose coating. When the loose fiber-bacterial cellulose suspension is filtered and dried, the adjacent bacterial cellulose forms a network and hornified to hold the otherwise loose fibers together.
The introduction of bacterial cellulose into the preform resulted in a significant increase of the mechanical properties of the fiber preforms. This can be attributed to the high stiffness and strength of the bacterial cellulose network. With this preform, renewable high performance hierarchical composites can also be manufactured by using conventional composite production methods, such as resin film infusion (RFI) or resin transfer molding (RTM). Here, we also describe the manufacturing of renewable hierarchical composites using double bag vacuum assisted resin infusion.

We present a novel method of manufacturing rigid and robust short natural fiber preforms using a papermaking process. Bacterial cellulose acts simultaneously as the binder for the loose fibers and provides rigidity to the fiber preforms. These preforms can be infused with a resin to produce truly green hierarchical composites.

制造业的鲁棒天然纤维预制体的利用细菌纤维素为粘结剂

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose ...

Preparation of Light-responsive Membranes by a Combined Surface Grafting and Postmodification Process

In order to modify the surface tension of commercial available track-edged polymer membranes, a procedure of surface-initiated polymerization is presented. The polymerization from the membrane surface is induced by plasma treatment of the membrane, followed by reacting the membrane surface with a methanolic solution of 2-hydroxyethyl methacrylate (HEMA). Special attention is given to the process parameters for the plasma treatment prior to the polymerization on the surface. For example, the influence of the plasma-treatment on different types of membranes (e.g.&#160;polyester, polycarbonate, polyvinylidene fluoride) is studied. Furthermore, the time-dependent stability of the surface-grafted membranes is shown by contact angle measurements. When grafting poly(2-hydroxyethyl methacrylate) (PHEMA) in this way, the surface can be further modified by esterification of the alcohol moiety of the polymer with a carboxylic acid function of the desired substance. These reactions can therefore be used for the functionalization of the membrane surface. For example, the surface tension of the membrane can be changed or a desired functionality as the presented light-responsiveness can be inserted. This is demonstrated by reacting PHEMA with a carboxylic acid functionalized spirobenzopyran unit which leads to a light-responsive membrane. The choice of solvent plays a major role in the postmodification step and is discussed in more detail in this paper. The permeability measurements of such functionalized membranes are performed using a Franz cell with an external light source. By changing the wavelength of the light from the visible to the UV-range, a change of permeability of aqueous caffeine solutions is observed.

A plasma-induced polymerization procedure is described for the surface-initiated polymerization on polymer membranes. Further postmodification of the grafted polymer with photochromic substances is presented with a protocol of conducting permeability measurements of light-responsive membranes.

通过结合表面接枝和修改后的过程光敏感膜的制备

In order to modify the surface tension of commercial available track-edged polymer membranes, a procedure of surface-initiated polymerization is ...

Generation of a Three-dimensional Full Thickness Skin Equivalent and Automated Wounding

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models reflect the human wound situation better than animal models. Although two-dimensional models are widely used to investigate processes such as cellular migration and proliferation, models that are more complex are required to gain a deeper knowledge about wound healing. Besides a suitable model system, the generation of precise and reproducible wounds is crucial to ensure comparable results between different test runs. In this study, the generation of a three-dimensional full thickness skin equivalent to study wound healing is shown. The dermal part of the models is comprised of human dermal fibroblast embedded in a rat-tail collagen type I hydrogel. Following the inoculation with human epidermal keratinocytes and consequent culture at the air-liquid interface, a multilayered epidermis is formed on top of the models. To study the wound healing process, we additionally developed an automated wounding device, which generates standardized wounds in a sterile atmosphere.

The goal of this protocol is to build up a three-dimensional full thickness skin equivalent, which resembles natural skin. With a specifically constructed automated wounding device, precise and reproducible wounds can be generated under maintenance of sterility.

三维全层皮肤的生成等效和自动伤人

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models ...

Alternating Magnetic Field-Responsive Hybrid Gelatin Microgels for Controlled Drug Release

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of smart soft devices for biomedical applications. Although a number of magnetically-responsive drug delivery systems have demonstrated efficacies through either in vitro proof of concept studies or in vivo preclinical applications, their use in clinical settings is still limited by their insufficient biocompatibility or biodegradability. Additionally, many of the existing platforms rely on sophisticated techniques for their fabrications. We recently demonstrated the fabrication of biodegradable, gelatin-based thermo-responsive microgel by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within a three-dimensional gelatin network. In this study, we present a facile method to fabricate a biodegradable drug release platform that enables a magneto-thermally triggered drug release. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and thermo-responsive polymers within gelatin-based colloidal microgels, in conjunction with an alternating magnetic field application system.

We present a facile method to fabricate a biodegradable gelatin-based drug release platform that is magneto-thermally responsive. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and poly(N-isopropylacrylamide-co-acrylamide) within a spherical gelatin micro-network crosslinked by genipin, in conjunction with an alternating magnetic field application system.

交变磁场敏感的混合明胶微凝胶药物控释

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of ...

Generation of ESC-derived Mouse Airway Epithelial Cells Using Decellularized Lung Scaffolds

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and cell-matrix interactions. Due to this complexity, recapitulation of lung development in vitro to promote differentiation of stem cells to lung epithelial cells has been challenging. In this protocol, decellularized lung scaffolds are used to mimic the 3-dimensional environment of the lung and generate stem cell-derived airway epithelial cells. Mouse embryonic stem cell are first differentiated to the endoderm lineage using an embryoid body (EB) culture method with activin A. Endoderm cells are then seeded onto decellularized scaffolds and cultured at air-liquid interface for up to 21 days. This technique promotes differentiation of seeded cells to functional airway epithelial cells (ciliated cells, club cells, and basal cells) without additional growth factor supplementation. This culture setup is defined, serum-free, inexpensive, and reproducible. Although there is limited contamination from non-lung endoderm lineages in culture, this protocol only generates airway epithelial populations and does not give rise to alveolar epithelial cells. Airway epithelia generated with this protocol can be used to study cell-matrix interactions during lung organogenesis and for disease modeling or drug-discovery platforms of airway-related pathologies such as cystic fibrosis.

This protocol efficiently directs mouse embryonic stem cell-derived definitive endoderm to mature airway epithelial cells. This differentiation technique uses 3-dimensional decellularized lung scaffolds to direct lung lineage specification, in a defined, serum-free culture setting.

用脱细胞支架龙ESC衍生鼠气道上皮细胞的生成

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and ...

Polyelectrolyte Complex for Heparin Binding Domain Osteogenic Growth Factor Delivery

During reconstructive bone surgeries, supraphysiological amounts of growth factors are empirically loaded onto scaffolds to promote successful bone fusion. Large doses of highly potent biological agents are required due to growth factor instability as a result of rapid enzymatic degradation as well as carrier inefficiencies in localizing sufficient amounts of growth factor at implant sites. Hence, strategies that prolong the stability of growth factors such as BMP-2/NELL-1, and control their release could actually lower their efficacious dose and thus reduce the need for larger doses during future bone regeneration surgeries. This in turn will reduce side effects and growth factor costs. Self-assembled PECs have been fabricated to provide better control of BMP-2/NELL-1 delivery via heparin binding and further potentiate growth factor bioactivity by enhancing in vivo stability. Here we illustrate the simplicity of PEC fabrication which aids in the delivery of a variety of growth factors during reconstructive bone surgeries.

Self-assembled polyelectrolyte complexes (PEC) fabricated from heparin and protamine were deposited on alginate beads to entrap and regulate the release of osteogenic growth factors. This delivery strategy enables a 20-fold reduction of BMP-2 dose in spinal fusion applications. This article illustrates the benefits and fabrication of PECs.

聚电解质复合物肝素结合域成骨生长因子交货

During reconstructive bone surgeries, supraphysiological amounts of growth factors are empirically loaded onto scaffolds to promote successful bone ...