Name: live cell imaging during mechanical stretch
Uploaded: 2015-08-19T13:00:00.000+00:00
Duration: 7 min 42 s
Description: Watch this Scientific Journal Video about Live Cell Imaging during Mechanical Stretch at JoVE.com

Yazarlar, desteklerinden dolayı Memphis Üniversitesi&#39;nde Teknoloji Fedex Enstitüsü&#39;ne teşekkür isterim. Yazarlar Memphis (David Butler, Jackie Carter, Dominick Cleveland, Jacob Shaffer) Üniversitesi Makine Mühendisliği Bölümü&#39;nde kıdemli tasarım proje grubunun öğrencileri kabul etmek istiyorum, motor kontrolü için University of Memphis Mühendislik Teknolojisi bölümünden Daniel Kohn Hücre kültüründe yardım ettikleri için, Dr. Bin Teng ve Bayan Charlean Luellen. Bu eser K01 HL120912 (ER) ve R01 HL123540 (CMW) tarafından desteklenmiştir.

Tutma Hücre Kültürü Medya Kuyu Walls (nihai ürün için Şekil 1D bakınız) Membran 1. İnşaat <ol><li> Kollajen I ile kaplanmış polidimetilsiloksan (PDMS) yaprak kullanarak, neşter veya bir kalıp esnek membran hatlarını kesti. </li><li> Depolanması için bir 60 mm Petri kabı, her membran yerleştirin. </li><li> Duvarların Oluşturma: <ol><li> B (sertleştirici) elastomer elastomer A: 1 ağırlık oranında, bir 10 PDMS karıştırın. </li><li> 50 ml tüpler içine tam olarak karıştırılır PDMS 5 ml dökün. </li><li> Yatay bir hibridizasyon fırında sertleşmemiş PDMS ile 50 ml&#39;lik tüpler yerleştirin. </li><li> Kür süresinde 8 rpm&#39;de kaplamak için tüplerin iç duvarları rotor işlevini kullanın. Oda sıcaklığında, PDMS tam 2 gün içinde tedavi edilecek. </li><li> Steril hücre kültürü kaputu tüpten PDMS çıkarın. </li><li> Yeni bir jilet kullanarak, bölümlerde yüksekliği 4 mm içine PDMS silindir bölümlemek. </li><li> Membran wa olarak görev yapacak bölümleri, koyunlls, izin vermeden bir Petri kabı kabına duvarları buruşuk olmak. </li></ol></li><li> Petri kabındaki iki korurken, bir zar üzerinde PDMS bir duvar seçin ve merkezi. </li><li> Tutkal olarak kullanılmak üzere, duvarın dış çevre üzerinde (1 oranında 10) hafifçe sertleşmemiş PDMS yerleştirin. Bu sıvı tutmak için olmadığı duvar ve zar arasındaki boşluk oluşmasını önler. </li><li> Her petri çanağı tamamlanmış membran içeren ve tedavi etmek için 24 saat boyunca 70 ° C&#39;de bir fırın içinde kapalı bir yer. </li></ol> Kalibrasyon için Kelepçe Yerinden veya Radyal Büyüme (Şekil 2) Motorlu Münavebesindeki 2. Korelasyon <ol><li> Motorun kontrol yazılımını başlatın. </li><li> Motor yazılımı manuel ayarını kullanarak cihazın kelepçeleri yerinden. </li><li> Mesafeyi ölçün ve kelepçeler minimum ve maksimum deplasman hem de kelepçeler karşıt arasındaki motor sayısı konumunu kaydedin. </li><li> D yüzde değişim hesaplayınMotor sayımı (~ 0-75k sayımları) &#39;in bir fonksiyonu olarak kelepçeler arasında istance. Bu membran üzerinde elde edilen maksimum potansiyel gerginlik gösterecektir. </li></ol> Fare Akciğer Epitel Hücre Hattı Stretch 3. Uygulama (MLE12) <ol><li> Oyuk başına esnek bir zar üzerinde 2.500.000 hücreleri (Aşama 1) Tohum MLE12 hücreler iki gün içinde birleşmiş olması. tohum yoğunluğu farklı hücre tipleri için farklı olabilir. </li><li> Mekanik aktüatör tamamen rahat bir konumda olduğundan emin olun. <ol><li> Hücre kültürü ortamı çıkarın. </li><li> Altı kelepçenin her iki delikler, 1.5 mm biyopsi kalıplar kullanılarak membran çıkıntıları (Şekil 1D bakınız). deliklerin radyal yerleştirme membran deneyimleri başlangıçta ön gerilim miktarını belirler. Hiçbir ön gerilim isteniyorsa membran sekmelerde 20.5 mm yarıçapında delikler. </li><li> Delikli delik kelepçeler içinde iğne ile sıraya ile sedye üzerinde membran yerleştirin.Yerde üst kelepçeleri yerleştirin. Vidaları zaman alternatif tarafta bir tane sıkın. </li><li> 1 ml hücre kültür ortamı ekleyin. </li></ol></li><li> Işık yolu ile membran orta merkezleme mikroskop sahnede cihazı yerleştirin. </li><li> Sahneye cihazı sabitlemek için bant veya mıknatısları (mümkünse) kullanın. Bir kez, sabit, mikroskop aşamasında kontrol ünitesi ile mekanik bir cihazın düzlem (zara paralel) ve dikey (z-yönü) kontrol eder. </li><li> Manuel motor dönüş 20 konumunu ve hızını kontrol ederek üretici tarafından sağlanan yazılım ile streç uygulayın. </li></ol> Mitokondriyal reaktif oksijen türlerinin 4. Ölçüm (ROS) <ol><li> Hücreler birleştiklerinde, sonra, doğrudan hücrelerde mitokondriyal süperoksit göstergesi (5 uM nihai konsantrasyon) ile RT DMEM 1-2 ml ekleyin. </li><li> 37 ° C&#39;de 10 dakika süreyle inkübe edin. </li><li> Yıkama Hücreler nazikçe tampon maddesi ile üç defa bir su banyosu içinde ısıtılmıştır37 ° C. </li><li> Hemen dik konfokal mikroskop altında zaten yerinde sedyeye (Adım 2.2) esnek membran yerleştirin. </li><li> Fenol-kırmızı içermeyen ortamda ve HEPES 25 mM DMEM 1 ml ilave edilir. </li><li> 510/580 nm uyarım / emisyon filtreleri ayarlayın. </li><li> Görüntü birden alanlar her 15 dk mitokondriyal süperoksit üretiminin istenilen zaman ders oluşturmak için. </li><li> Çekilen görüntülerin itibaren, rekor floresan yoğunluğu floresan yoğunluğu miktarının yeteneğine sahip yazılımı kullanarak her zaman aralığında histogramlar. </li></ol> Streç ve Atomik Kuvvet Mikroskobu 5. Uygulama (AFM) Not: Bu adımlarda, belirli bir AFM ve optik mikroskop kombinasyonu (Şekil 4 ve Malzeme Listesi) için verilmiştir. <ol><li> Deney için AFM hazırlayın. <ol><li> Z-doğrultusunda maksimum pozisyona AFM baş yüksekliğini artırın. </li><li> AFM ayakları üzerine genişleticiler koyUçağı kaldırmak hangi AFM konsol temas örnek de. Numune ve AFM kafası mekanik bir cihaz yüksekliğine uyacak kaldırılması gerekir. </li></ol></li><li> (Varsa) optik mikroskop hazırlayın. <ol><li> AFM tarayıcı plakasını sökün. İstenilen hedefe çıkarın. </li><li> Amaç için bir ayırıcı ekleyin. aralama yüksekliği objektif ve belirli AFM set-up bağlı olacaktır, ancak gözlem uçağı sedye ve adaptör yüksekliği (Şekil eşit miktarda z-yönünde kayma olacağından optik görüntüleme isteniyorsa gerekli olduğunu 5A). AFM genellikle cihazın üzerinde bir optik yolundan düşük büyütme görüntüleme sağladığını unutmayın. </li><li> Konumu istenen amaç geri monte edin. AFM geri tarayıcıyı yerleştirin. </li><li> AFM yazılımını başlatın. Floresan ölçümleri için ışık kaynağı dahil gerekli bütün ışık kaynakları başlatın. </li><li> Bir konsol kiriş ile bir çip monte olduğunuarzu edilen ölçümler için uygundur. Canlı hücrelerin elastik modülü ölçerken 200 pN / nm ya da daha az sertlik tercih edilmektedir. </li><li> Lazer hizalama ve cihaz üzerine monte edilmiş bir cam lamel üzerinde üreticinin önerilerine göre konsol sertliği kalibre. </li></ol></li><li> Aşama 1 &#39;de olduğu gibi bir zar hazırlama, ancak şu değişiklikler yapılmıştır. <ol><li> Hemen germe aygıtının için membran takmadan önce, yüksekliği yaklaşık 1 mm duvar kesti. Bu membran duvar ve yük hücresi arasında yaşanan girişimi önler. </li><li> 3.2.1-3.2.3 tarif edildiği gibi mekanik bir cihaz ile ilgili membran monte edin. </li><li> Bir dökülme durumunda AFM tarayıcı zarar görmesini önlemek için hücre kültürü ortamı çıkarın. </li><li> Çift bir adaptör (Şekil 5A) ile bir cihaz. Tarayıcının adaptörle mekanik cihaz yerleştirin. </li><li> İstenen gerilme gerinim seviyesine membran gerin. </li></ol></li><li&gt; Gergin hücrelerin Nano-girinti. <ol><li> Nedeniyle dökülme için AFM tarayıcı veya mikroskop zarar görmesini önlemek için hücreler üzerinde medya sınırlı (&lt;0.5 ml) hacmi ekleyin. </li><li> Membran ile konsol kiriş Engage. </li><li> Ilgi alanları taramak için belirli AFM cihazının protokolünü izleyin. </li></ol></li></ol>

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Yazarlar hiçbir rakip mali çıkarlarını olduğunu beyan ederim.

Mekanik streç sırasında canlı hücre görüntüleme için benzersiz bir cihaz geliştirildi; ve bu cihaz, akciğer epitelyal hücre mechanobiology incelemek için bir protokol kullanılmıştır. Ön çalışmalarda, tek tutulan streç bronşiyal epitel hücrelerde mitokondrial süperoksid üretimini uyardığı tespit edildi. Buna ek olarak, mekanik zorlanma artmış seviyeleri alveolar epitel hücrelerinin bir tek tabaka bütünlüğü doğrudan bozukluklara sebep olduğu gösterilmiştir. <p class="jove_conte...

Hücreler, bir çok dokuda mekanik yüklere maruz kalır ve bu, mekanik uyarma gen ekspresyonu, büyüme faktörleri, sitokinler, ya da hücre dışı matrisin yeniden verildiği şekillerindeki değişiklikleri teşvik etmek ve 1-4 hücre iskeletinin gösterilmiştir. Bu tür mekanik uyarıcılara karşı hücre içi sinyallere mechanotransduction 5-7 işleminde meydana gelir. Solunum sisteminde, mechanotransduction bir sonucu, reaktif oksijen türlerinin (ROS), siklik bir çekme gücü mevcudiyetinde pulmoner epitel hücrelerinde 8,9 ve pro-inflamatuar sitokinlerin 10 artıştır. Güçlü kanıtlar ayrıca aşırı gerilim soyu hücrelerinin 11-14 biyokimyasal yanıtların yanı sıra, alveol epiteline yaralanması doğrudan yol açtığını göstermektedir. Odak Burada mekanik deformasyon akciğer hücrelerinin yanıtı esas olmasına rağmen, mechanotransduction neden yollar bas önemli bir rol oynardamar tonusu 15 düzenlenmesinde ve büyüme plağının 16 geliştirilmesi dahil olmak üzere insan vücudunda birçok dokuda, bir ic fonksiyonu. mechanotransduction artan ilgi kültürlenmiş hücreler ve doku için fizyolojik olarak ilgili mekanik yüklerin uygulanması için çok sayıda cihazı geliştirilmesi ile sonuçlanmıştır. Özel olarak, doku tarafından yaşanan mekanik yüklenme ortak bir biçimi olan bir çekme gücü, uygulama tertibatının 11,17-19 popülerdir. Ancak, mevcut cihazların çoğu ya doku mühendisliği uygulamaları için biyoreaktör olarak tasarımlanmış veya streç ile gerçek zamanlı görüntüleme için elverişli değildir. Bu nedenle, mechanotransduction arasında yolların araştırılmasını kolaylaştırmak için gerilim hücre ve dokuları görselleştirmek araçları ve yöntemlerinin geliştirilmesi için bir ihtiyaç vardır. Burada, bir düzlem mekanik germe cihazı tasarlanmıştır ve protokoller m uygulamak için geliştirilmiştirultiple dokulara soyunun formları ve hücreler, gerçek zaman (Şekil 1A-D), biyokimyasal ve mekanik yanıtların görüntüleme imkan verir. Cihaz, esnek bir membran kavramak ve yaklaşık% 20 (Şekil 1B) bir düzlemsel radyal distansiyon yukarı uygulamak için çevresel olarak yerleştirilmiş olan eşit aralıklı kelepçeler kullanılmaktadır. Motor (Şekil 1C) inkübatör dışına yerleştirilmiş ve motor satıcı tarafından sunulan özel yazılım tarafından kontrol edilir ise çalıştırma tertibatı, uzun bir zaman süresi için bir hücre kültürü inkübatöründe yerleştirilebilir. kas gerginliği ve gevşeme eşit altı sedye kelepçeler sürüş bir iç cam döner lineer sürücü bağlanır. Mekanik cihaz ek olarak, özel esnek zarların mekanik bir sistemde kullanılmak üzere ticari olarak temin edilebilen hücre kültürü hazır zarlarından oluşturulmuştur. Yaklaşık bir çapı olan, dairesel sonra duvar (28 mm) yapılmıştır ve hücreler, sadece iyi tarif edilen suş profili bu bölgede kültürlenebilir böylece esnek bir zar üzerine bağlanmıştır. Harekete geçirme cihazı içinde bu membranların yerleştirilmesi, esnek bir zarın merkezinde tek tip ve izotropik streynini sağlayabilir olup olmadığını belirlemek için, sonlu eleman analizi, ticari olarak temin edilebilen yazılımı (Şekil 1E-F) kullanılarak yapıldı. Esnek zar simetrik sınır koşulları ve örgü için tüm dörtgen elemanlar kullanan ile modellenmiştir. Şekil 1F gösterilen maksimum asal zorlanma kontur arsa görülen eş halkalar zorlanma izotropik dağılımını göstermektedir. membran tarafından hissedilen gerginlik yükleme (Şekil 2) vasıtasıyla işaretler görüntüleri kaydedilerek sürekli olarak ölçüldü. Şekil 2B, radyal ve eksenel yönde ölçülen ortalama membran soyu yaklaşık doğrusal olduğunu göstermektediruygulanan motoru ile ilgili olarak% 20 oranında bir maksimum doğrusal suşu kadar sayar. Geri dinlenme pozisyonuna geri çekilmesi sırasında ölçülen kıyasla distansiyon sırasında ölçülen gerilme düzeyleri arasında anlamlı bir fark yoktu. Daha sonra, özel bir esnek zar üzerinde kültürlenmiş insan bronşiyal epitel hücreleri (16HBE) ve bunların çekirdeklerinin değiştirme ölçüldü. Bütün hücre yer değiştirmesi, bir dijital mikroskop ile kaydedilen faz kontrast görüntüleri ile ölçüldü ise 16HBE hücrelerinin floresan etiketli (DAPI) çekirdekler, konfokal mikroskop altında bir 20x objektif kullanılarak görüntülendi. Şekil 3&#39;te görüldüğü gibi, çekirdek yer değiştirmesi ile ölçülen gerilme, up ~% 20 lineer streyn zar üzerinde işaretlerin yer değiştirmesi ile ölçülen benzer olmuştur. Bu membranların uygulanan gerilme yapışık hücrelere iletilen olduğunu doğrulamaktadır. Geleneksel mikroskop özel cihazın kullanımını anlatan protokolleri ve atomik kuvvet mikroskopE, aşağıdaki adımlarda verilmiştir.

<table><tbody><tr><td>SmartMotor NEMA 34: 3400 Series</td><td>MOOG Animatics</td><td>SM3416D</td><td>Integrated motor, controller, amplifier, encoder and communications bus</td></tr><tr><td>Flexcell Membrane (Collagen I coated)</td><td>Flexcell International Corp</td><td>SM2-1010C</td><td>3.5&quot;&amp;nbsp;x&amp;nbsp;5.25&quot;&amp;nbsp;x&amp;nbsp;0.020&quot;</td></tr><tr><td>Sylgard 184</td><td>Dow Corning Corporation</td><td></td><td>10:1</td></tr><tr><td>Hoechst 33342&amp;nbsp;</td><td>Sigma-Aldrich</td><td>H1399</td><td>DAPI stain</td></tr><tr><td>MitoSOX</td><td>Sigma-Aldrich</td><td>M36008</td><td></td></tr><tr><td>Tiron</td><td>Sigma-Aldrich</td><td>D7389&amp;nbsp;</td><td>mitochondrial superoxide label</td></tr><tr><td>DMEM</td><td></td><td></td><td>superoxide inhibitor</td></tr><tr><td>FBS</td><td></td><td></td><td></td></tr><tr><td>HEPES</td><td></td><td></td><td></td></tr><tr><td>50 ml tubes</td><td>Fisher Scientific</td><td>06-443-19</td><td>Any centriguge tube can be used to create an area for imaging.</td></tr><tr><td>Hybridization oven</td><td>Bellco Glass</td><td></td><td></td></tr><tr><td>MLE12 Cells</td><td>ATCC</td><td>CRL-2110</td><td>Mouse Lung Epithelial Cells&amp;nbsp;</td></tr><tr><td>16HBE cells</td><td>ATCC</td><td>CRL-2741</td><td>Human Bronchial Epithelial Cells</td></tr><tr><td colspan="4">&lt;strong&gt;AFM Indentation Experiments&lt;/strong&gt;</td></tr><tr><td>Cantilever Beams for Nano-indentation</td><td>Budget Sensors</td><td>Si-Ni30</td><td></td></tr><tr><td>AFM&amp;nbsp;</td><td>Asylum Research</td><td>MFP3D</td><td></td></tr><tr><td>Olympus microscope</td><td>Olympus</td><td>IX-71</td><td>Inverted microscope with 20X and 40X objectives.</td></tr><tr><td>AFM Leg Extenders</td><td>Asylum Research</td><td>Not available</td><td>AFM microscope</td></tr><tr><td colspan="4">&lt;strong&gt;Finite Element Analyses&lt;/strong&gt;</td></tr><tr><td>ABAQUS</td><td>Simulia</td><td>6.12</td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Software&lt;/strong&gt;</td></tr><tr><td>ImageJ</td><td>NIH</td><td></td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Microscopes&lt;/strong&gt;</td></tr><tr><td>Digital microscope</td><td>Life Technologies</td><td>EVOS XL Core</td><td>Initially a self standing company, now owned by Life Technologies.</td></tr><tr><td>Confocal microscope</td><td>Zeiss</td><td>LSM 710</td><td>2-photon upright microscope</td></tr></tbody></table>

live cell imaging during mechanical stretch

There is currently a significant interest in understanding how cells and tissues respond to mechanical stimuli, but current approaches are limited in their capability for measuring responses in real time in live cells or viable tissue. A protocol was developed with the use of a cell actuator to distend live cells grown on or tissues attached to an elastic substrate while imaging with confocal and atomic force microscopy (AFM). Preliminary studies show that tonic stretching of human bronchial epithelial cells caused a significant increase in the production of mitochondrial superoxide. Moreover, using this protocol, alveolar epithelial cells were stretched and imaged, which showed direct damage to the epithelial cells by overdistention simulating one form of lung injury in vitro. A protocol to conduct AFM nano-indentation on stretched cells is also provided.

Reaktif Oksijen Türleri ve Deformasyon Daha önce yapılan çalışmalar, siklik streç 21 tepki olarak hava yolu ve alveolar epitel hücrelerinin, reaktif oksijen türlerinin (ROS) artış göstermiştir. Reaktif oksijen türleri, molekülleri ve lipitler, proteinler, polisakkaritler, nükleik asitler, 22-24, yüksek reaktiviteye sahip moleküler oksijenden türemiş serbest radikalleri içerir. ROS, ortak bir hücre içi iyon kanalı fonksiyonu düzenleyen b...

Watch this Scientific Journal Video about Live Cell Imaging during Mechanical Stretch at JoVE.com

Live Cell Imaging during Mechanical Stretch

A novel imaging protocol was developed using a custom motor-driven mechanical actuator to allow the measurement of real time responses to mechanical strain in live cells. Relevant to mechanobiology, the system can apply strains up to 20% while allowing near real-time imaging with confocal or atomic force microscopy.

Mekanik Stretch sırasında Canlı Hücre Görüntüleme

There is currently a significant interest in understanding how cells and tissues respond to mechanical stimuli, but current approaches are limited in ...

live-cell-imaging-during-mechanical-stretch

Research

JoVE Journal

Bioengineering

10.3K Görüntüleme.  University of Tennessee Health Science Center. A novel imaging protocol was developed using a custom motor-driven mechanical actuator to allow the measurement of real time responses to mechanical strain in live cells. Relevant to mechanobiology, the system can apply strains up to 20% while allowing near real-time imaging with confocal or atomic force microscopy. 

Video: Live Cell Imaging during Mechanical Stretch

Mechanical Stimulation of Stem Cells Using Cyclic Uniaxial Strain

The role of mechanical forces in the development and maintenance of biological tissues is well documented, including several mechanically regulated phenomena such as bone remodeling, muscular hypertrophy, and smooth muscle cell plasticity. However, the forces involved are often extremely complex and difficult to monitor and control in vivo. To better investigate the effects of mechanical forces on cells, we have developed an in vitro method for applying uniaxial cyclic tensile strain to adherent cells cultured on elastic membranes. This method utilizes a custom-designed bioreactor with a motorized cam-rotor system to apply the desired force. Here we present a step-by-step video protocol demonstrating how to assemble the various components of each "stretch chamber", including, in this case, a silicone membrane with micropatterned topography to orient the cells with the direction of the strain. We also describe procedures for sterilizing the chambers, seeding cells onto the membrane, latching the chamber into the bioreactor, and adjusting the mechanical parameters (i.e. magnitude and rate of strain). The procedures outlined in this particular protocol are specific for seeding human mesenchymal stem cells onto silicone membranes with 10 &micro;m wide channels oriented parallel to the direction of strain. However, the methods and materials presented in this system are flexible enough to accommodate a number of variations on this theme: strain rate, magnitude, duration, cell type, membrane topography, membrane coating, etc. can all be tailored to the desired application or outcome. This is a robust method for investigating the effects of uniaxial tensile strain applied to cells in vitro.

It is widely understood that mechanical forces in the body can influence cell differentiation and proliferation. Here we present a video protocol demonstrating the use of a custom-built bioreactor for delivering uniaxial cyclic tensile strain to stem cells cultured on flexible micropatterned substrates.

Devirli Tek Eksenli Gerilme kullanarak Kök Hücre Mekanik Uyarım

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

Biyoloji

An Experimental System to Study Mechanotransduction in Fetal Lung Cells

Mechanical forces generated in utero by repetitive breathing-like movements and by fluid distension are critical for normal lung development. A key component of lung development is the differentiation of alveolar type II epithelial cells, the major source of pulmonary surfactant. These cells also participate in fluid homeostasis in the alveolar lumen, host defense, and injury repair. In addition, distal lung parenchyma cells can be directly exposed to exaggerated stretch during mechanical ventilation after birth. However, the precise molecular and cellular mechanisms by which lung cells sense mechanical stimuli to influence lung development and to promote lung injury are not completely understood. Here, we provide a simple and high purity method to isolate type II cells and fibroblasts from rodent fetal lungs. Then, we describe an in vitro system, The Flexcell Strain Unit, to provide mechanical stimulation to fetal cells, simulating mechanical forces in fetal lung development or lung injury. This experimental system provides an excellent tool to investigate molecular and cellular mechanisms in fetal lung cells exposed to stretch. Using this approach, our laboratory has identified several receptors and signaling proteins that participate in mechanotransduction in fetal lung development and lung injury.

Mechanical forces play a key role in lung development and lung injury. Here, we describe a method to isolate rodent fetal lung type II epithelial cells and fibroblasts and to expose them to mechanical stimulation using an in vitro system.

Fetal Akciğer Hücrelerinde Mechanotransduction Okumak Deneysel Bir Sistem

Mechanical forces generated in utero by repetitive breathing-like movements and by fluid distension are critical for normal lung development. A key ...

Biyomühendislik

Stretching Micropatterned Cells on a PDMS Membrane

Mechanical forces exerted on cells and/or tissues play a major role in numerous processes. We have developed a device to stretch cells plated on a PolyDiMethylSiloxane (PDMS) membrane, compatible with imaging. This technique is reproducible and versatile. The PDMS membrane can be micropatterned in order to confine cells or tissues to a specific geometry. The first step is to print micropatterns onto the PDMS membrane with a deep UV technique. The PDMS membrane is then mounted on a mechanical stretcher. A chamber is bound on top of the membrane with biocompatible grease to allow gliding during the stretch. The cells are seeded and allowed to spread for several hours on the micropatterns. The sample can be stretched and unstretched multiple times with the use of a micrometric screw. It takes less than a minute to apply the stretch to its full extent (around 30%). The technique presented here does not include a motorized device, which is necessary for applying repeated stretch cycles quickly and/or computer controlled stretching, but this can be implemented. Stretching of cells or tissue can be of interest for questions related to cell forces, cell response to mechanical stress or tissue morphogenesis. This video presentation will show how to avoid typical problems that might arise when doing this type of seemingly simple experiment.

This manuscript presents a technique to apply or release forces on adherent cells or tissues using unidirectional stretching.

PDMS Zarında Micropatterned Hücreler germe

Mechanical forces exerted on cells and/or tissues  play a major role in numerous processes. We have developed a device to stretch  cells plated on a ...

A Novel Stretching Platform for Applications in Cell and Tissue Mechanobiology

Tools that allow the application of mechanical forces to cells and tissues or that can quantify the mechanical properties of biological tissues have contributed dramatically to the understanding of basic mechanobiology. These techniques have been extensively used to demonstrate how the onset and progression of various diseases are heavily influenced by mechanical cues. This article presents a multi-functional biaxial stretching (BAXS) platform that can either mechanically stimulate single cells or quantify the mechanical stiffness of tissues. The BAXS platform consists of four voice coil motors that can be controlled independently. Single cells can be cultured on a flexible substrate that can be attached to the motors allowing one to expose the cells to complex, dynamic, and spatially varying strain fields. Conversely, by incorporating a force load cell, one can also quantify the mechanical properties of primary tissues as they are exposed to deformation cycles. In both cases, a proper set of clamps must be designed and mounted to the BAXS platform motors in order to firmly hold the flexible substrate or the tissue of interest. The BAXS platform can be mounted on an inverted microscope to perform simultaneous transmitted light and/or fluorescence imaging to examine the structural or biochemical response of the sample during stretching experiments. This article provides experimental details of the design and usage of the BAXS platform and presents results for single cell and whole tissue studies. The BAXS platform was used to measure the deformation of nuclei in single mouse myoblast cells in response to substrate strain and to measure the stiffness of isolated mouse aortas. The BAXS platform is a versatile tool that can be combined with various optical microscopies in order to provide novel mechanobiological insights at the sub-cellular, cellular and whole tissue levels.

We present in this article a novel stretching platform that can be used to investigate single cell responses to complex anisotropic biaxial mechanical deformation and quantify the mechanical properties of biological tissues.

Hücre ve Doku mechanobiology Applications A Novel Germe Platformu

Tools that allow the application of mechanical forces to cells and tissues or that can quantify the mechanical properties of biological tissues have ...

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.

Tümleşik Optik ve Atomik Kuvvet Mikroskobu eğitimi Mekanik Uyarım Canlı Hücre Tepki

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 ...

High-resolution Imaging of Nuclear Dynamics in Live Cells under Uniaxial Tensile Strain

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the effect of applied extracellular tensile strain on cell populations in vitro via biochemical assays, a device has previously been designed which can be fabricated simply and is small enough to fit inside tissue culture incubators, as well as on top of microscope stages. However, the previous design of the polydimethylsiloxane substratum did not allow high-resolution subcellular imaging via oil-immersion objectives. This work describes a redesigned geometry of the polydimethylsiloxane substratum and a customized imaging setup that together can facilitate high-resolution subcellular imaging of live cells while under applied strain. This substratum can be used with the same, earlier designed device and, hence, has the same advantages as listed above, in addition to allowing high-resolution optical imaging. The design of the polydimethylsiloxane substratum can be improved by incorporating a grid which will facilitate tracking the same cell before and after the application of strain. Representative results demonstrate high-resolution time-lapse imaging of fluorescently labeled nuclei within strained cells captured using the method described here. These nuclear dynamics data give insights into the mechanism by which applied tensile strain promotes differentiation of oligodendrocyte progenitor cells.&#160;

Using a previously designed device to apply mechanical strain to adherent cells, this paper describes a redesigned substratum geometry and a customized apparatus for high-resolution single-cell imaging of strained cells with a 100x oil immersion objective.

Tek eksenli çekme gerinim altında canlı hücrelerde nükleer dinamiklerin yüksek çözünürlüklü görüntülenmesi

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the ...

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.

Fazlararası Hücre Çekirdek Mekanik Özellikleri Probe Biyofiziksel Tahliller: Yüzey Gerilme Uygulama ve Microneedle Manipülasyon

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

Controlled Strain of 3D Hydrogels under Live Microscopy Imaging

External forces are an important factor in tissue formation, development, and maintenance. The effects of these forces are often studied using specialized in vitro stretching methods. Various available systems use 2D substrate-based stretchers, while the accessibility of 3D techniques to strain soft hydrogels, is more restricted. Here, we describe a method that allows external stretching of soft hydrogels from their circumference, using an elastic silicone strip as the sample carrier. The stretching system utilized in this protocol is constructed from 3D-printed parts and low-cost electronics, making it simple and easy to replicate in other labs. The experimental process begins with polymerizing thick (&#62;100 &#956;m) soft fibrin hydrogels (Elastic Modulus of ~100 Pa) in a cut-out at the center of a silicone strip. Silicone-gel constructs are then attached to the printed-stretching device and placed on the confocal microscope stage. Under live microscopy the stretching device is activated, and the gels are imaged at various stretch magnitudes. Image processing is then used to quantify the resulting gel deformations, demonstrating relatively homogenous strains and fiber alignment throughout the gel&#8217;s 3D thickness (Z-axis). Advantages of this method include the ability to strain extremely soft hydrogels in 3D while executing in situ microscopy, and the freedom to manipulate the geometry and size of the sample according to the user&#8217;s needs. Additionally, with proper adaptation, this method can be used to stretch other types of hydrogels (e.g., collagen, polyacrylamide or polyethylene glycol) and can allow for analysis of cells and tissue response to external forces under more biomimetic 3D conditions.

The presented method involves uniaxial stretching of 3D soft hydrogels embedded in silicone rubber while allowing live confocal microscopy. Characterization of the external and internal hydrogel strains as well as fiber alignment are demonstrated. The device and protocol developed can assess the response of cells to various strain regimes.

Canlı Mikroskopi Görüntüleme Altında 3D Hidrojellerin Kontrollü Suşu

External forces are an important factor in tissue formation, development, and maintenance. The effects of these forces are often studied using specialized ...

Method for High Speed Stretch Injury of Human Induced Pluripotent Stem Cell-derived Neurons in a 96-well Format

Traumatic brain injury (TBI) is a major clinical challenge with high morbidity and mortality. Despite decades of pre-clinical research, no proven therapies for TBI have been developed. This paper presents a novel method for pre-clinical neurotrauma research intended to complement existing pre-clinical models. It introduces human pathophysiology through the use of human induced pluripotent stem cell-derived neurons (hiPSCNs). It achieves loading pulse duration similar to the loading durations of clinical closed head impact injury. It employs a 96-well format that facilitates high throughput experiments and makes efficient use of expensive cells and culture reagents. Silicone membranes are first treated to remove neurotoxic uncured polymer and then bonded to commercial 96-well plate bodies to create stretchable 96-well plates. A custom-built device is used to indent some or all of the well bottoms from beneath, inducing equibiaxial mechanical strain that mechanically injures cells in culture in the wells. The relationship between indentation depth and mechanical strain is determined empirically using high speed videography of well bottoms during indentation. Cells, including hiPSCNs, can be cultured on these silicone membranes using modified versions of conventional cell culture protocols. Fluorescent microscopic images of cell cultures are acquired and analyzed after injury in a semi-automated fashion to quantify the level of injury in each well. The model presented is optimized for hiPSCNs but could in theory be applied to other cell types.

Here we present a method for a human in vitro model of stretch injury in a 96-well format on a timescale relevant to impact trauma. This includes methods for fabricating stretchable plates, quantifying the mechanical insult, culturing and injuring cells, imaging, and high content analysis to quantify injury.

Pluripotent kök hücre kaynaklı nöronlarda bir 96-şey Format yöntemi için yüksek hızlı streç yaralanma insan indüklenen

Traumatic brain injury (TBI) is a major clinical challenge with high morbidity and mortality. Despite decades of pre-clinical research, no proven ...

Nörobilim

Human Saphenous Vein Endothelial Cell Isolation and Exposure to Controlled Levels of Shear Stress and Stretch

Coronary artery bypass graft (CABG) surgery is a procedure to revascularize ischemic myocardium. Saphenous vein remains used as a CABG conduit despite the reduced long-term patency compared to arterial conduits. The abrupt increase of hemodynamic stress associated with the graft arterialization results in vascular damage, especially the endothelium, that may influence the low patency of the saphenous vein graft (SVG). Here, we describe the isolation, characterization, and expansion of human saphenous vein endothelial cells (hSVECs). Cells isolated by collagenase digestion display the typical cobblestone morphology and express endothelial cell markers CD31 and VE-cadherin. To assess the mechanical stress influence, protocols were used in this study to investigate the two main physical stimuli, shear stress and stretch, on arterialized SVGs. hSVECs are cultured in a parallel plate flow chamber to produce shear stress, showing alignment in the direction of the flow and increased expression of KLF2, KLF4, and NOS3. hSVECs can also be cultured in a silicon membrane that allows controlled cellular stretch mimicking venous (low) and arterial (high) stretch. Endothelial cells' F-actin pattern and nitric oxide (NO) secretion are modulated accordingly by the arterial stretch. In summary, we present a detailed method to isolate hSVECs to study the influence of hemodynamic mechanical stress on an endothelial phenotype.

We describe a protocol to isolate and culture human saphenous vein endothelial cells (hSVECs). We also provide detailed methods to produce shear stress and stretch to study mechanical stress in hSVECs.

İnsan safen ven endotel hücre izolasyonu ve kontrollü kayma stresi ve gerilme seviyelerine maruz kalma

Coronary artery bypass graft (CABG) surgery is a procedure to revascularize ischemic myocardium. Saphenous vein remains used as a CABG conduit despite the ...