Yazarlar osteokondral fişler sürecini sarma katkılarından dolayı UMC Utrecht de gelişme mekaniği grubundan Sn Jeroen van den Berg ve Bay Matthijs Wassink minnettarlıklarını ifade etmek istiyorum. Bu çalışma Hollandalı Artrit Vakfı tarafından Grant tarafından desteklenmiştir.

NOT: Burada sunulan protokol son araştırma makaleleri 6, 8, 9, deneysel ve hesaplamalı prosedürlerden benimsenmiştir. Protokol, Şekil 1 &#39;de gösterilmektedir. kadavra malzemeler Utrecht Üniversitesi Veteriner fakültesi izniyle toplanmıştır. 1. Numune ve Banyo Hazırlama <ol><li> Serin fosfat tamponlu tuzlu su (PBS) püskürtme sırasında aşırı ısınma ve daha sonra kıkırdak hasarı önlemek için ölçüye göre matkap ucu (Şekil 1) kullanılarak kadavra at femoral kondil silindirik osteokondral tapaları (8.5 mm çap) delin. </li><li> üst üste bindirilmiş banyosunun yanal yayılmanın en aza indirmek için kılıfı küçülen bir plastik ile osteokondral fişleri Termo büzülme. <ol><li> th kıkırdak ile osteokondral fiş monteE plastik küçülen yen içinde başlangıçta üst ve ona sıcak hava üfleyerek uygulayın. ısıyla ilgili zarar görmesini önlemek için kıkırdağın yüzeyinde ıslak pamuk parçaları ekleyin. </li></ol></li><li> Ayrıca yüklü (örneğin, 650 uL, 420 mM, iyoksaglat, Molekül Ağırlığı (MA) = 1.269 Da, şarj = 1) ve nötr (650 uL, 420 mM, iyodiksanol, MW = 1,550 Da), çözünen sonlu banyoları hazırlayın. </li><li> Bir şırınga kullanılarak kıkırdak yüzeyinde hazırlanmış sonlu banyoları yük ve oda sıcaklığında (Şekil 2A) ile deneyler sırasında buharlaşmasını önlemek için sarılmış örnek üzerinde mantar fiş yerleştirin. nötr solüt taşınmasını araştırmak üzere iodixanol banyosu yerleştirin ve kıkırdak yüzeyine negatif yüklü çözünmüş madde taşıma yeri iyoksaglat banyosu incelemek için. </li></ol> 2. Görüntüleme ve Görüntü İşleme <ol><li> bir mikro-CT motorlu aşamasına bağlı bir ölçüye tutucu üzerinde mantar tapa ile izole sarılmış numuneler. Yeri to kadar kontrast maddesi çözeltisi yukarı bakacak şekilde kaplı olduğu bir kıkırdak yüzey örnek. </li><li> Mikro-BT (40 x 40 x 40 um 3 voksel, 2 dakika tarama süresini, 90 kV tüp voltajı ve 180 uA tüp akımı) kıkırdak, subkondral plakadan oluşan bir görüş alanını kullanarak tarama ve sonlu denge durumuna (48 saat kadar) bir kaç zaman noktasında banyo (Şekil 2A) ulaşılır. konsantrasyon değerleri zamanla değişmez zaman denge durumuna ulaşılır. </li><li> Üreticinin yazılımını kullanarak İlgi (ROI) Bölge konumlandırılmasını kolaylaştırmak için ilk resme göre farklı zaman noktalarında 3D görüntüler Kayıt (örneğin Analiz). </li><li> Dönüştürme 3D üreticinin yazılımını kullanarak bunları işleme önce 2B Tagged Image File Format (TIFF) yığını haline mikro-BT görüntüleri yeniden. </li><li> Küresel segmentin (ImageJ&gt; ayarlama&gt; Eşiği) subkondral kemik ve kıkırdak yerindenyazılımda banyosu yalan. </li><li> Farklı zaman noktalarında kıkırdak ortalama gri değeri elde edilir önceki adımda oluşturulan kıkırdak maskesi kullanarak (ImageJ&gt;&gt; ölçün analiz). </li><li> kıkırdak ilk banyo konsantrasyonu ve ilk kontrast maddesi konsantrasyonu dikkate alındığında, çözünen maddelerin gerçek konsantrasyonu ortalama gri değerleri dönüştürmek için lineer kalibrasyon eğrisi kullanır. Önceki veriler, gri değerler kontrast ajanlarının konsantrasyonu ile doğrusal bir ilişki muhafaza gerçeğini destekler. </li><li> Deneysel zaman noktalarında karşı çözünen madde konsantrasyonunu çizilir. </li></ol> 3. Sayısal Modelleme NOT: Bu problemde difüzyon deneysel sınır koşulu ile uyumludur (z ekseni boyunca) 1D gerçekleşecek varsayılır. Bu nedenle, geometri keyfi oluşturulabilir. <ol><li> Sonlu banyosu göre kıkırdak çoklu bölge modelini oluşturmak: 1) Kıkırdak yüzeysel bölgesi oluşan<html> (Toplam kıkırdak kalınlığının% 20), orta bölge (toplam kıkırdak kalınlığının% 50) ve derin bölge (toplam kıkırdak kalınlığının% 30) 12 ve FEBio 13, 14 (Şekil 2B 2) sonlu banyosu). </li><li> FEBio kıkırdak ve banyo farklı bölgeleri, mekanik ve fiziksel özellikleri atamak. Young modülü (10 MPa) üstte banyosu ile uygulanan ozmotik basınca dayanıklı ve bu nedenle aşırı deformasyonlar kıkırdak korumak için yeterince yüksek olduğu varsayılmıştır. <ol><li> 10 -3 mm bir hidrolik geçirgenliği kullanım 4 / Ns ve simülasyonlar 8 banyo 0 kullanımı gerçek çözünen yayılma katsayısının Poisson oranı, 9. </li></ol></li><li> Örgü (8-düğüm trilinear altı yüzlü elemanları) oluşturmak ve sınırların yakın hassaslaştırmada (Şekil 2B)class = &quot;xref&quot;&gt; 8, 9. </li><li> Bifazik-çözünen modeli <ol><li> buna tekabül eden banyo ve etkili bir basınç ilk bir eriyen madde konsantrasyonuna uygulanır. 15 9&#39;da etkili basıncın açıklamaya bakın. </li><li> Farklı kıkırdak bölgelerinde öngörülen difüzyon katsayılarına göre zaman eğrileri çözünen konsantrasyonunu elde etmek için geçici bir modda modeli çalıştırın. </li></ol></li><li> multifazik modeli Not: banyo ve doku arasındaki elektrik dalgalanma banyo ve doku hem de iki tek değerli karşıt-iyonlar eklenerek atlatılabilir. <ol><li> kararlı durum modeller için: istenen değere FCD artırırken kıkırdak ve üstte uzanan banyosu içinde aynı etkili sıvı basınçları ve konsantrasyonları kullanır. </li><li> Geçici modeller için: yeterince yüksek banyosunda çözünmüë difüzyon katsayısını tutarak iyice karıştırılmış sonlu banyosu oluşturun. enjekte etmekbanyosuna banyo hava arayüzünden çözünen istenen konsantrasyon değerine ulaşmak için. </li><li> Geçici: Önceki adımda reçete solüt konsantrasyonu sınır koşulu kaldırıp gerçek difüzyon katsayısına sonlu banyosu difüzyon katsayısını dönmek. </li><li> Farklı kıkırdak bölgelerde uygulanan FCDs ve difüzyon katsayılarına göre çözünen konsantrasyonu-zaman eğrilerinin elde edilmesi için bir model çalıştırın. </li></ol></li><li> FEBio-MATLAB arayüzü <ol><li> Otomatik FEBio ve arsa konsantrasyonu-zaman eğrilerinin (FEBio-MATLAB arayüzü) 8, 9, simülasyon gerçekleştirmek için bir MATLAB geliştirir. </li><li> FEBio-MATLAB arayüzünü kullanarak kıkırdak bölgelerinde difüzyon katsayıları ve FCDs değiştirin. FEBio modelleri çalıştırın ve çözünen konsantrasyonu-zaman eğrilerinin 9 8 ekstrakte edin. </li><li> Deneysel elde çözünen konsantrasyonu-zaman eğrileri karşılaştırMinimum kök göre farklı kıkırdak bölgelerinde veriler ve elde difüzyon katsayılarının setleri ve FCDs kare hata (RMSE) 8, 9 anlamına gelir. </li></ol></li></ol><img alt="Şekil 1" class="xfigimg" src="/files/ftp_upload/54984/54984fig1.jpg" /> Şekil 1: Deney Düzeneği. A), ısmarlama bir matkap ucu yardımıyla örnek ekstraksiyon prosedürü. B) Mikro-BT görüntüleme prosedürü difüzyon sürecini izlemek üzere. <a href="http://ecsource.jove.com/files/ftp_upload/54984/54984fig1large.jpg" target="_blank">Bu rakamın büyük halini görmek için buraya tıklayın.</a> <img alt="şekil 2" class="xfigimg" src="/files/ftp_upload/54984/54984fig2.jpg" /> Şekil 2: Şematik.A) Deney tasarımı. Sonlu banyo, kıkırdak ve bunlarla ilgili örgü yüzeysel, orta ve derin bölgelerde oluşan B) Çok bölgeli hesaplama modeli. <a href="http://ecsource.jove.com/files/ftp_upload/54984/54984fig2large.jpg" target="_blank">Bu rakamın büyük halini görmek için buraya tıklayın.</a>

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Yazarlar ifşa hiçbir şey yok.

Biz eklem kıkırdağı boyunca nötr ve yüklü çözünenlerin difüzyon çalışması için bir sonlu elemanlar modelleme prosedürü ile kombine deneysel protokol sundu. Son çalışmalara göre, önerilen modeller doğru eklem kıkırdağında 8, 9 farklı bölgeleri arasında nötr (bifazik-çözünen) her ikisinin de taşıma ve negatif yüklü (çok fazlı) çözünmüş tarif olabilir. Yaygın eklem kıkırdağı işlevsel böyle OA ilerlemesi <sup clas...

<html> Moleküler taşıma dile eklemlerin homeostazı hayati bir rol oynar, artiküler tedavilerin teslim kıkırdak ve kontrastlı kıkırdak görüntüleme 1, 2, 3. Bu tür kıkırdak entegrasyonu ve eksiklik, çözünen yük ve boyut olarak osmolalitesi ve nakil oranı 4, 5, 6 etkileyebilir kıkırdak ile temas içinde banyo konsantrasyonu gibi faktörler. Her bölge farklı konsantrasyonlarda ve büyük ekstrasellüler matris moleküllerin yönelimlerinin oluşur, çünkü nötr ya da yüklü, ya çözünen, nakliyesi, eklem kıkırdağı bölgeleri arasında farklı olabilir, yani proteoglikanlar (PG) ve kollajen tip II, 1, 7, 8, 9,lass = &quot;xref&quot;&gt; 10, 11. Daha da önemlisi, yüklü çözünen taşıma eklem kıkırdağının 8, 9 boyunca artar hücre dışı matris içinde negatif sabit yük ihtiva proteoglikanlar konsantrasyonuna büyük ölçüde bağlı olabilir. Osteoartrit (OA), böylece kıkırdak boyunca difüzyonu çalışmanın önemini gösteren, ilerledikçe Bu parametreler özellikle de sabit yük yoğunluğu (FKH), kolajen fibrilleri ve kıkırdak arasında su içeriği varyasyon yönünü değişiklik olabilir. Bu çalışmada, bir protokol 6, 8, 9 doğru difüzyon sonlu banyosu modelinde nötr ve yüklü çözünen maddeleri kullanılarak çeşitli sınır şartları altında difüzyon araştırmak için önerilmektedir daha önce kurulmuş deney ve bilgisayar çalışmalara dayanmaktadır. To yöntemler kıkırdak ve gelişmiş iki fazlı-çözünen ve çok fazlı sonlu eleman modelleri ile desteklenen bir sonlu banyosunda içeren bir sistemin, mikro-bilgisayarlı tomografi görüntüleme (mikro-CT) oluşmaktadır önerilmiştir. Bu modeller, eklem kıkırdağının çeşitli dilimleri arasında nötr ve yüklü moleküllerin yanı sıra FCDs difüzyon katsayılarını elde etmek sağlar. bu modelleri kullanarak, bir kıkırdak ve bindirilirken sonlu banyosu arasındaki etkileşimleri incelemek için kullanılabilir difüzyon nötr ve yüklü moleküllerin davranışlarının daha iyi anlayabilirsiniz.

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			<td style="width:201px;">Negatively charged contrast agent</td>
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an experimental and finite element protocol to investigate the transport of neutral and charged solutes across articular cartilage

<html> Osteoartrit (OA) kıkırdak ve kondral kemik dejenerasyonu ile ilgili olan bir zayıflatıcı bir hastalıktır. Bu büyük bir kimyasal bozunma örneğin, proteoglikan kaybı ve kolajen fibril bozulmasını karşılaşır olarak eklem kıkırdağı dejenerasyonu ölçüde yük taşıma işlevini bozar. OA sırasında kimyasal zarar mekanizmalarını incelemek için ümit verici bir yol, bir dış çözünen kıkırdak örnekleri ortaya çıkarmak ve moleküllerin difüzyon izlemektir. Sağlıklı kıkırdağa kıyasla farklı difüzyon özelliklerine oluşturur eklem kıkırdağı üzerinde hareket ederken, kıkırdak hasarı (örneğin, konsantrasyon ve temel makromoleküllerin konfigürasyonunda) derecesi dış solutların çarpışma enerji kaybı ile ilişkilidir. Bu çalışmada, çeşitli adımlardan oluşur ve daha önce geliştirilen deneysel mikro C dayanan bir protokol, tanıtmak14px; &quot;&gt; omputed T omography (mikro-CT) ve sonlu eleman modeli ilk olarak iki fazlı-çözünen ve difüzyon katsayılarını elde etmek için çok fazlı sonlu eleman modelleri üzerine tatbik edilmesi izler mikro-CT, kullanılarak kaydedilir yüklenmiş ve yüklenmemiş iyotlu moleküllerin taşınması. ve kıkırdak dilimleri arasında yük yoğunlukları sabit.

Burada sağlanan temsili sonuçları önceki araştırma makaleleri 6, 8, 9, 16 ile kabul edilmiştir. OA olarak, eklem kıkırdağı önemli değişiklikler en önemlisi GAG kaybı ve kolajen fibril hasar 17, 18, <sup class="xref"...

Watch this Scientific Journal Video about An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage at JoVE.com

An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage

Geçenlerde geliştirilen deneysel ve sayısal yöntemlerin yardımıyla eklem kıkırdağının genelinde Yüklü ve yüksüz moleküllerin taşınmasını araştırmak için bir protokol öneriyoruz.

Deneysel ve Sonlu Eleman Protokolü Eklem Kıkırdak genelinde Nötr ve Yüklü Çözünenlerin Ulaştırma Araştırma

Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular ...

an-experimental-finite-element-protocol-to-investigate-transport

Research

JoVE Journal

Bioengineering

6.2K Görüntüleme.  Delft University of Technology (TU Delft).  Geçenlerde geliştirilen deneysel ve sayısal yöntemlerin yardımıyla eklem kıkırdağının genelinde Yüklü ve yüksüz moleküllerin taşınmasını araştırmak için bir protokol öneriyoruz. 

Video: An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage

Patterned Photostimulation with Digital Micromirror Devices to Investigate Dendritic Integration Across Branch Points

Light is a versatile and precise means to control neuronal excitability. The recent introduction of light sensitive effectors such as channel-rhodopsin and caged neurotransmitters have led to interests in developing better means to control patterns of light in space and time that are useful for experimental neuroscience. One conventional strategy, employed in confocal and 2-photon microscopy, is to focus light to a diffraction limited spot and then scan that single spot sequentially over the region of interest. This approach becomes problematic if large areas have to be stimulated within a brief time window, a problem more applicable to photostimulation than for imaging. An alternate strategy is to project the complete spatial pattern on the target with the aid of a digital micromirror device (DMD). The DMD approach is appealing because the hardware components are relatively inexpensive and is supported by commercial interests. Because such a system is not available for upright microscopes, we will discuss the critical issues in the construction and operations of such a DMD system. Even though we will be primarily describing the construction of the system for UV photolysis, the modifications for building the much simpler visible light system for optogenetic experiments will also be provided. The UV photolysis system was used to carryout experiments to study a fundamental question in neuroscience, how are spatially distributed inputs integrated across distal dendritic branch points. The results suggest that integration can be non-linear across branch points and the supralinearity is largely mediated by NMDA receptors.

Digital micromirror devices (DMD) can generate complex patterns in time and space with which to control neuronal excitability. Issues relevant to the design, construction, and operation of DMD systems are discussed. Such a system enabled the demonstration of non-linear integration across distal dendritic branch points.

Desenli Photostimulation Şube Noktaları Arasında Dendritik Entegrasyon Araştırma Digital Micromirror Cihazlar

Light is a versatile and precise means to control neuronal excitability. The recent introduction of light sensitive effectors such as channel-rhodopsin ...

Biyomühendislik

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.

Plasenta karşısında Ksenobiyotik ve Nanomalzemelerin Ulaştırma Hızı belirlenmesi kullanarak<em&gt; Ex vivo</em&gt; İnsan Plasental Perfüzyon Modeli

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

Models and Methods to Evaluate Transport of Drug Delivery Systems Across Cellular Barriers

Sub-micrometer carriers (nanocarriers; NCs) enhance efficacy of drugs by improving solubility, stability, circulation time, targeting, and release. Additionally, traversing cellular barriers in the body is crucial for both oral delivery of therapeutic NCs into the circulation and transport from the blood into tissues, where intervention is needed. NC transport across cellular barriers is achieved by: (i) the paracellular route, via transient disruption of the junctions that interlock adjacent cells, or (ii) the transcellular route, where materials are internalized by endocytosis, transported across the cell body, and secreted at the opposite cell surface (transyctosis). Delivery across cellular barriers can be facilitated by coupling therapeutics or their carriers with targeting agents that bind specifically to cell-surface markers involved in transport. Here, we provide methods to measure the extent and mechanism of NC transport across a model cell barrier, which consists of a monolayer of gastrointestinal (GI) epithelial cells grown on a porous membrane located in a transwell insert. Formation of a permeability barrier is confirmed by measuring transepithelial electrical resistance (TEER), transepithelial transport of a control substance, and immunostaining of tight junctions. As an example, ~200&#160;nm polymer NCs are used, which carry a therapeutic cargo and are coated with an antibody that targets a cell-surface determinant. The antibody or therapeutic cargo is labeled with 125I for radioisotope tracing and labeled NCs are added to the upper chamber over the cell monolayer for varying periods of time. NCs associated to the cells and/or transported to the underlying chamber can be detected. Measurement of free 125I allows subtraction of the degraded fraction. The paracellular route is assessed by determining potential changes caused by NC transport to the barrier parameters described above. Transcellular transport is determined by addressing the effect of modulating endocytosis and transcytosis pathways.

Many therapeutic applications require safe and efficient transport of drug carriers and their cargoes across cellular barriers in the body. This article describes an adaptation of established methods to evaluate the rate and mechanism of transport of drug nanocarriers (NCs) across cellular barriers, such as the gastrointestinal (GI) epithelium.

Modelleri ve Hücresel Engeller Arasında İlaç Taşıyıcı Sistemlerin Transport Değerlendirmesinde Yöntemleri

Sub-micrometer carriers (nanocarriers; NCs) enhance efficacy of drugs by improving solubility, stability, circulation time, targeting, and release. ...

Human Cartilage Tissue Fabrication Using Three-dimensional Inkjet Printing Technology

Bioprinting, which is based on thermal inkjet printing, is one of the most attractive enabling technologies in the field of tissue engineering and regenerative medicine. With digital control&#160;cells, scaffolds, and growth factors can be precisely deposited to the desired two-dimensional (2D) and three-dimensional (3D) locations rapidly. Therefore, this technology is an ideal approach to fabricate tissues mimicking their native anatomic structures. In order to engineer cartilage with native zonal organization, extracellular matrix composition (ECM), and mechanical properties, we developed a bioprinting platform using a commercial inkjet printer with simultaneous photopolymerization capable for 3D cartilage tissue engineering. Human chondrocytes suspended in poly(ethylene glycol) diacrylate (PEGDA) were printed for 3D neocartilage construction via layer-by-layer assembly. The printed cells were fixed at their original deposited positions, supported by the surrounding scaffold in simultaneous photopolymerization. The mechanical properties of the printed tissue were similar to the native cartilage. Compared to conventional tissue fabrication, which requires longer UV exposure, the viability of the printed cells with simultaneous photopolymerization was significantly higher. Printed neocartilage demonstrated excellent glycosaminoglycan (GAG) and collagen type II production, which was consistent with gene expression. Therefore, this platform is ideal for accurate cell distribution and arrangement for anatomic tissue engineering.

The methods described in this paper show how to convert a commercial inkjet printer into a bioprinter with simultaneous UV polymerization. The printer is capable of constructing 3D tissue structure with cells and biomaterials. The study demonstrated here constructed a 3D neocartilage.

Üç boyutlu Mürekkep Püskürtmeli Baskı Teknolojisi Kullanımı İnsan Kıkırdak Doku Fabrikasyon

Bioprinting, which is based on thermal inkjet printing, is one of the most attractive enabling technologies in the field of tissue engineering and ...

A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials

This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. brain, liver, tendon, fat, etc.) when exposed to high strain rates. This study utilized a Split-Hopkinson Pressure Bar (SHPB) to generate strain rates of 100-1,500 sec-1. The SHPB employed a striker bar consisting of a viscoelastic material (polycarbonate). A sample of the biomaterial was obtained shortly postmortem and prepared for SHPB testing. The specimen was interposed between the incident and transmitted bars, and the pneumatic components of the SHPB were activated to drive the striker bar toward the incident bar. The resulting impact generated a compressive stress wave (i.e. incident wave) that traveled through the incident bar. When the compressive stress wave reached the end of the incident bar, a portion continued forward through the sample and transmitted bar (i.e. transmitted wave) while another portion reversed through the incident bar as a tensile wave (i.e. reflected wave). These waves were measured using strain gages mounted on the incident and transmitted bars. The true stress-strain behavior of the sample was determined from equations based on wave propagation and dynamic force equilibrium. The experimental stress-strain response was three dimensional in nature because the specimen bulged. As such, the hydrostatic stress (first invariant) was used to generate the stress-strain response. In order to extract the uniaxial (one-dimensional) mechanical response of the tissue, an iterative coupled optimization was performed using experimental results and Finite Element Analysis (FEA), which contained an Internal State Variable (ISV) material model used for the tissue. The ISV material model used in the FE simulations of the experimental setup was iteratively calibrated (i.e. optimized) to the experimental data such that the experiment and FEA strain gage values and first invariant of stresses were in good agreement.

The current study prescribes a coupled experiment-finite element simulation methodology to obtain the uniaxial dynamic mechanical response of soft biomaterials (brain, liver, tendon, fat, etc.). The multiaxial experimental results that arose because of specimen bulging obtained from Split-Hopkinson Pressure Bar testing were rendered to a uniaxial true stress-strain behavior when simulated through iterative optimization of the finite element analysis of the biomaterial.

Yumuşak Biyomalzeme Yüksek Deformasyon Hızı Mekanik Tepki değerlendirilmesi için Coupled Deney-sonlu Eleman Modelleme Metodolojisi

This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. ...

3D Hydrogel Scaffolds for Articular Chondrocyte Culture and Cartilage Generation

Human articular cartilage is highly susceptible to damage and has limited self-repair and regeneration potential. Cell-based strategies to engineer cartilage tissue offer a promising solution to repair articular cartilage. To select the optimal cell source for tissue repair, it is important to develop an appropriate culture platform to systematically examine the biological and biomechanical differences in the tissue-engineered cartilage by different cell sources. Here we applied a three-dimensional (3D) biomimetic hydrogel culture platform to systematically examine cartilage regeneration potential of juvenile, adult, and osteoarthritic (OA) chondrocytes. The 3D biomimetic hydrogel consisted of synthetic component poly(ethylene glycol) and bioactive component chondroitin sulfate, which provides a physiologically relevant microenvironment for in vitro culture of chondrocytes. In addition, the scaffold may be potentially used for cell delivery for cartilage repair in vivo. Cartilage tissue engineered in the scaffold can be evaluated using quantitative gene expression, immunofluorescence staining, biochemical assays, and mechanical testing. Utilizing these outcomes, we were able to characterize the differential regenerative potential of chondrocytes of varying age, both at the gene expression level and in the biochemical and biomechanical properties of the engineered cartilage tissue. The 3D culture model could be applied to investigate the molecular and functional differences among chondrocytes and progenitor cells from different stages of normal or aberrant development.

Cartilage repair represents an unmet medical challenge and cell-based approaches to engineer human articular cartilage are a promising solution. Here, we describe three-dimensional (3D) biomimetic hydrogels as an ideal tool for the expansion and maturation of human articular chondrocytes.

Eklem Kondrosit Kültür ve Kıkırdak Üretimi için 3D hidrojel iskeleleri

Human articular cartilage is highly susceptible to damage and has limited self-repair and regeneration potential. Cell-based strategies to engineer ...

An Experimental Protocol for Assessing the Performance of New Ultrasound Probes Based on CMUT Technology in Application to Brain Imaging

The possibility to perform an early and repeatable assessment of imaging performance is fundamental in the design and development process of new ultrasound (US) probes. Particularly, a more realistic analysis with application-specific imaging targets can be extremely valuable to assess the expected performance of US probes in their potential clinical field of application.
The experimental protocol presented in this work was purposely designed to provide an application-specific assessment procedure for newly-developed US probe prototypes based on Capacitive Micromachined Ultrasonic Transducer (CMUT) technology in relation to brain imaging.
The protocol combines the use of a bovine brain fixed in formalin as the imaging target, which ensures both realism and repeatability of the described procedures, and of neuronavigation techniques borrowed from neurosurgery. The US probe is in fact connected to a motion tracking system which acquires position data and enables the superposition of US images to reference Magnetic Resonance (MR) images of the brain. This provides a means for human experts to perform a visual qualitative assessment of the US probe imaging performance and to compare acquisitions made with different probes. Moreover, the protocol relies on the use of a complete and open research and development system for US image acquisition, i.e. the Ultrasound Advanced Open Platform (ULA-OP) scanner.
The manuscript describes in detail the instruments and procedures involved in the protocol, in particular for&#160;the calibration, image acquisition and registration of US and MR images. The obtained results prove the effectiveness of the overall protocol presented, which is entirely open (within the limits of the instrumentation involved), repeatable, and covers the entire set of acquisition and processing activities for US images.

The development of new ultrasound (US) probes based on Capacitive Micromachined Ultrasonic Transducer (CMUT) technology requires an early realistic assessment of imaging capabilities. We describe a repeatable experimental protocol for US image acquisition and comparison with magnetic resonance images, using an ex vivo bovine brain as an imaging target.

Beyin görüntüleme uygulamaya CMUT teknolojisi tabanlı yeni ultrason probları performansını değerlendirmek için deneysel bir iletişim kuralı

The possibility to perform an early and repeatable assessment of imaging performance is fundamental in the design and development process of new ...

Creating a Structurally Realistic Finite Element Geometric Model of a Cardiomyocyte to Study the Role of Cellular Architecture in Cardiomyocyte Systems Biology

With the advent of three-dimensional (3D) imaging technologies such as electron tomography, serial-block-face scanning electron microscopy and confocal microscopy, the scientific community has unprecedented access to large datasets at sub-micrometer resolution that characterize the architectural remodeling that accompanies changes in cardiomyocyte function in health and disease. However, these datasets have been under-utilized for&#160;investigating the role of cellular architecture remodeling in cardiomyocyte function. The purpose of this protocol is to outline how to create an accurate finite element model of a cardiomyocyte using high resolution electron microscopy and confocal microscopy images. A detailed and accurate model of cellular architecture has significant potential to provide new insights into cardiomyocyte biology, more than experiments alone can garner. The power of this method lies in its ability to computationally fuse information from two disparate imaging modalities of cardiomyocyte ultrastructure to develop one unified and detailed model of the cardiomyocyte. This protocol outlines steps to integrate electron tomography and confocal microscopy images of adult male Wistar (name for a specific breed of albino rat) rat cardiomyocytes to develop a half-sarcomere finite element model of the cardiomyocyte. The procedure generates a 3D finite element model that contains an accurate, high-resolution depiction (on the order of ~35 nm) of the distribution of mitochondria, myofibrils and ryanodine receptor clusters that release the necessary calcium for cardiomyocyte contraction from the sarcoplasmic reticular network (SR) into the myofibril and cytosolic compartment. The model generated here as an illustration does not incorporate details of the transverse-tubule architecture or the sarcoplasmic reticular network and is therefore a minimal model of the cardiomyocyte. Nevertheless, the model can already be applied in simulation-based investigations into the role of cell structure in calcium signaling and mitochondrial bioenergetics, which is illustrated and discussed using two case studies that are presented following the detailed protocol.

This protocol outlines a novel method to create a spatially detailed finite element model of the intracellular architecture of cardiomyocytes from electron microscopy and confocal microscopy images. The power of this spatially detailed model is demonstrated using case studies in calcium signaling and bioenergetics.

Cardiomyocyte sistemleri Biyoloji hücresel mimarisi rolü eğitim için bir Cardiomyocyte bir yapısal olarak gerçekçi Sonlu elemanlar geometrik Model oluşturma

With the advent of three-dimensional (3D) imaging technologies such as electron tomography, serial-block-face scanning electron microscopy and confocal ...

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

Organ engineering is a novel strategy to generate liver organ substitutes that can potentially be used in transplantation. Recently, in vivo liver engineering, including in vivo organ decellularization followed by repopulation, has emerged as a promising approach over ex vivo liver engineering. However, postoperative survival was not achieved. The aim of this study is to develop a novel surgical technique of in vivo selective liver lobe perfusion in rats as a prerequisite for in vivo liver engineering. We generate a circuit bypass only through the left lateral lobe. Then, the left lateral lobe is perfused with heparinized saline. The experiment is performed with 4 groups (n = 3 rats per group) based on different perfusion times of 20 min, 2 h, 3 h, and 4 h. Survival, as well as the macroscopically visible change of color and the histologically determined absence of blood cells in the portal triad and the sinusoids, is taken as an indicator for a successful model establishment. After selective perfusion of the left lateral lobe, we observe that the left lateral lobe, indeed, turned from red to faint yellow. In a histological assessment, no blood cells are visible in the branch of the portal vein, the central vein, and the sinusoids. The left lateral lobe turns red after reopening the blocked vessels. 12/12 rats survived the procedure for more than one week. We are the first to report a surgical model for in vivo single liver lobe perfusion with a long survival period of more than one week. In contrast to the previously published report, the most important advantage of the technique presented here is that perfusion of 70% of the liver is maintained throughout the whole procedure. The establishment of this technique provides a foundation for in vivo partial liver engineering in rats, including decellularization and recellularization.

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

We establish a novel surgical technique for an in vivo single liver lobe perfusion model in rat as a prerequisite for further studying in vivo partial liver engineering in the future.

Sıçan Vivo içinde kısmi karaciğer Dairesi'nde için bir temel olarak yeni bir cerrahi teknik

Organ engineering is a novel strategy to generate liver organ substitutes that can potentially be used in transplantation. Recently, in vivo liver ...

Fabrication of Decellularized Cartilage-derived Matrix Scaffolds

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage research has focused on the development of regenerative scaffolds. This article describes the development of scaffolds that are completely derived from natural cartilage extracellular matrix, coming from an equine donor. Potential applications of the scaffolds include producing allografts for cartilage repair, serving as a scaffold for osteochondral tissue engineering, and providing in vitro models to study tissue formation. By decellularizing the tissue, the donor cells are removed, but many of the natural bioactive cues are thought to be retained. The main advantage of using such a natural scaffold in comparison to a synthetically produced scaffold is that no further functionalization of polymers is required to drive osteochondral tissue regeneration. The cartilage-derived matrix scaffolds can be used for bone and cartilage tissue regeneration in both in vivo and in vitro settings.

Decellularized cartilage-derived scaffolds can be used as a scaffold to guide cartilage repair and as a means to regenerate osteochondral tissue. This paper describes the decellularization process in detail and provides suggestions to use these scaffolds in in vitro settings.

Decellularized matris kıkırdak elde edilen iskele imalatı

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage ...