This work was funded by a New Faculty Award II from the California Institute of Regenerative Medicine (CIRM; RN2-00921-1), NIH-funded National Research Award (F32-HL104924), and CIRM Training Grant (TG21163). Materials were provided by: Glycosan Biosystems Inc / BioTime and Dr. Stephen Badylak (University of Pittsburgh)

1 Criação de placas PNIPAAm revestidas <ol><li> Dissolve-se o 2,6 g de PNIPAAm em 2 ml de uma solução de hexano a 60% de tolueno / 40%. </li><li> Aquecer a mistura a 60 ° C durante 10 minutos agitou-se, até que a PNIPAAm é dissolvido. </li><li> Cortar papel de filtro para um círculo de diâmetro 60 mm e coloque o papel no funil de Buchner. </li><li> Filtrar a solução através de Buchner Funil para a pré-pesado copo de vidro (não use plástico, como o hexano vai derreter plásticos). </li><li> Colocar a proveta e o conteúdo para um vácuo de sino (24 psi) S / N (16 horas). Nota: Até o resíduo é reagido com isopropílico vai oxidar para ter certeza que não entra em contato com o oxigênio. </li><li> Pesar no copo para estabelecer o peso do PNIPAAm. </li><li> Adicionar álcool isopropílico para a PNIPAAm, criando uma 50/50 w / w solução. </li><li> Coloque 2 ml da solução sobre a superfície da placa de cultura de tecidos, e no revestimento, durante 5 min, sob luz UV. </li><li> Lava-se a placa com 2 ml de PBS quente duas vezesantes de usar para cultura de células. </li></ol> 2 Criação de Fichas de celulares Nota: as folhas da pilha de células primárias para o órgão-alvo podem ser criadas através de um número de métodos diferentes, ou por revestimento de superfícies de cultura de tecidos com o polímero termo-sensível, tal como descrito aqui. Placas termossensíveis Pré-revestidos também são oferecidos por um número de fornecedores. Nota: Este protocolo é para a cultura usando um prato de 35 mm. Resumidamente, as células são primeiro incubadas a 37 ° C durante um mínimo de 24 horas à confluência para estabelecer conexões laterais entre as células adjacentes. Para soltar as folhas de células, as placas são sujeitas a temperaturas inferiores a 32 ° C. A camada de células é então transferido para a matriz fibrosa base forte contendo um hidrogel permissiva neovascular com as células endoteliais vasculares. <ol><li> Isolar a população de células. Nota: Este método é dependente dos procedimentos de derivação individuais e o tipo de células. Rato mu liso aórticocélulas LECSA (RASMC) são utilizadas neste exemplo. Estas são células primárias de músculo liso isoladas a partir da aorta abdominal de um rato. </li><li> Lavam-se as células com 2 ml de PBS quente. </li><li> Adicionar 3 ml de tripsina (ou outro / solução dissociando clivagem) para as células durante 5 min. </li><li> Inibir a tripsina por adição de 3 ml do meio de cultura, ou uma solução tampão de fosfato (PBS) contendo 10% de soro fetal bovino (FBS). </li><li> Recolher as células num tubo cónico e contagem de uma alíquota. </li><li> Rodar as células a 1.000 rpm (228 xg) durante 5 min. </li><li> Aspirar o sobrenadante e ressuspender as células no seu meio de crescimento (mais SmGM2 kit bala meio de cultura é usada para RASMC). </li><li> Coloque a mídia que contém as células em um termo-sensível placa 35 mm - PNIPAAm placa revestida com uma concentração que vai atingir 100% de confluência. Nota: Para RASMCs que o número foi determinado como sendo de 100.000 células / cm 2. No entanto, devido à perda de células durante a passagem, 120% do que va<html> lue é usado. </li><li> Colocar numa incubadora a 37 ° CO / N. Nota: É importante manter as células a 37 ° C, para manter a adesão de células à placa. </li></ol> 3: Preparação da Matriz Fundamental Nota: Várias matrizes fibrosas em 3D podem ser utilizados para a camada de matriz fibrosa forte entre as camadas de células delicadas. Alguns exemplos incluem: gelfoam, biovidro, materiais naturais acellularized 26 ou nanospun materiais 27,28 A matriz de bexiga do porco (UBM) utilizada nesses estudos foi generosamente fornecidos a partir de nosso colaborador, o Dr. Badylak 29. <ol><li> Antes de usar, determinar as características da matriz, incluindo a falta de conteúdo celular se descelularizados matriz é usado, 27,28 viabilidade celular específica, e o espaço vazio 22. </li><li> Cortar a matriz pré-esterilizados em um tamanho e forma desejados. Nota: Aqui, um furador é utilizada para cortar um círculo diâmetro de 4 mm. </li></ol>ve_title &quot;&gt; 4. células endoteliais de semeadura em um Neovascular Permissivo Hidrogel Nota: As células endoteliais podem ser obtidos a partir de uma variedade de fontes, incluindo a diferenciação de células estaminais ou progenitoras. Aqui, são utilizadas células HUVEC. <ol><li> Use qualquer hidrogel permissiva (fibrina, géis de colagénio), enquanto o tempo de reticulação é suficientemente curto para permitir que as células permanecem viáveis. Nota: Aqui, um gel de hialuronano (HA), com base reticulados com uma ponte de dissulfureto é utilizado. </li><li> Prepare o hidrogel de HA, de acordo com o protocolo da empresa. </li><li> Recolher as células endoteliais e dispersam-se numa solução de uma única célula utilizando tripsina 1x. Nota: Accutase ou dissociação celular Tampão também poderia ser utilizada para a dispersão de células individuais. </li><li> Desactivar a enzima tripsina, utilizando uma quantidade igual de inibidor de tripsina de soja (que é importante que as células não entram em contacto com o soro) ou 10% de FBS em PBS, recolhendo a solução / células para um tubo de 15 ml. </li><li> CONT as células, e calcular o volume necessário para as dimensões de emenda (previamente quantificada). Nota: Para um patch 4 milímetros, aqui de 2 milhões de células endoteliais são usados. </li><li> Extrato de 2 milhões de células, e coloque em um novo tubo de 15 ml. </li><li> Giram em (228 xg) por 5 min. </li><li> Aspirar o sobrenadante, deixando as células como um sedimento num tubo cónico. </li><li> Misturar os materiais líquidos de HA e de gelatina numa proporção de 1: 1 ração. Em seguida, adicionar 80% do volume total dentro do tubo cónico contendo o sedimento. </li><li> Ressuspender as células endoteliais na mistura 1: 1 HA / Gelatina </li><li> Colocar as células em suspensão na mistura de HA / gelatina para a base de matriz fibrosa a partir do Passo 2. </li><li> Adicionar 1/5 (20 por cento) do volume total desejada do agente de reticulação </li><li> Incubar durante 1 hora a 37 ° C. </li></ol> 5. Isolamento de Folhas Celulares <ol><li> Retirar as placas tratadas com PNIPAAm 35 milímetros contendo as células a partir do incubador e colocar num capuz de cultura de células emRT. </li><li> Aspirar rapidamente o meio das células, e adicionar 2 ml de 6% de gelatina normal que foi aquecido a 37 ° C. </li><li> Enquanto que a gelatina está ainda quente, coloque a estrutura de metal em que a gelatina, submergindo-a abaixo da superfície da gelatina normal (Filme 1). </li><li> Coloque a totalidade da placa em gelo durante 5 a 7 minutos, permitindo que a gelatina endureça. </li><li> Após 7 min, uma espátula para separar cuidadosamente os bordos de gelatina do lado da placa, e em seguida utilizar uma pinça para levantar a estrutura de metal da placa Nota: A gelatina 6%, e a folha de célula deve levantar com a estrutura. </li><li> Mover a lâmina da célula para o prato e colocar na parte superior do conjunto de matriz de hidrogel de base fibrosa, ajustando cuidadosamente a estrutura no topo da construção. Nota: O lado apical da camada de células ainda estará na posição superior. </li><li> Adicionar 2 ml de meio morno (37 ° C). </li><li> Incubar S / N permitindo que a folha de células para aderirem à superfície do hidrogel. </li><li> Remover tele grade metálica após a solução aquece (aproximadamente 1 hora), ou no dia seguinte. </li></ol>

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We have nothing to disclose.

Os passos críticos no protocolo incluem: revestimento das superfícies das placas com o polímero thermoresponsive e manipular as folhas de células após o arrefecimento das placas. Como as células diferentes apresentam diferentes propriedades físicas, como adesividade, o tempo de elevação deve ser otimizado para cada tipo de célula diferente. O segundo, e mais importante desafio componente deste protocolo, centra-se na manipulação da camada de células, um aspecto crítico dos métodos para a montagem do tecid...

Injection of cells and/or single materials alone has shown variable success in other organ systems and limited success in cardiac regeneration.5,7-12 Currently, stem cell-derived cells are delivered to damaged tissue using a variety of delivery methods including: direct cell injection into tissue and perfusion into the blood supply.13-17 Others have implanted cells alone, materials alone and/or in combination with material carriers to help regenerate damaged organs.18-21 This design combines multiple strategies that provide material strength, patterning in multiple materials and multiple cell types. 
Specifically, the base acellularized fibrous matrix provides the foundational physical strength to the construct, making it suitable for suturing in into the patient, if necessary. The void spaces in the base matrix are filled with endothelial cells in a neovascular permissive hydrogel22 for rapidly establishing vascularization of the implanted construct. This composite is then integrated with pre-patterned cell sheets that allow enhanced cell-to-cell communication, more closely mimic the native tissue.1,23-25 The overall production process for the layered cellular patch is outlined by the flowchart in Figure 1.

<table border="0" cellpadding="0" cellspacing="0" width="695">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:207px;">Table of Reagents:</td>
			<td style="width:128px;"></td>
			<td style="width:140px;"></td>
			<td style="width:221px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Reagent</td>
			<td style="width:128px;">Company</td>
			<td style="width:140px;">Catalogue number</td>
			<td style="width:221px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Calcein-AM</td>
			<td style="width:128px;">Invitrogen</td>
			<td style="width:140px;">C3099</td>
			<td style="width:221px;">Cell tracker / live dye</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Lysotracker Red</td>
			<td style="width:128px;">Invitrogen</td>
			<td style="width:140px;">L7528</td>
			<td style="width:221px;">Cell tracker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Neutral Red</td>
			<td style="width:128px;">Sigma</td>
			<td style="width:140px;">N7005</td>
			<td style="width:221px;">Visible Cell dye</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:207px;">pNIPAAM</td>
			<td style="width:128px;">Sigma Aldrich</td>
			<td style="width:140px;">412780250</td>
			<td style="width:221px;">Poly(N-isopropylacrylamide)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Toluene</td>
			<td style="width:128px;">Sigma Aldrich</td>
			<td style="width:140px;">244511-1L</td>
			<td style="width:221px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Hexane</td>
			<td style="width:128px;">Sigma Aldrich</td>
			<td style="width:140px;">296090-1L</td>
			<td style="width:221px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">RAOSMC</td>
			<td style="width:128px;">Lonza</td>
			<td style="width:140px;">R-ASM-580</td>
			<td style="width:221px;">Rat Aortic Smooth Muscle Cells</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:207px;">SmGM2</td>
			<td style="width:128px;">Lonza</td>
			<td style="width:140px;">CC-4149</td>
			<td style="width:221px;">Smooth Muscle Media</td>
		</tr>
		<tr height="24">
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tissue engineering: construction of a multicellular 3d scaffold for the delivery of layered cell sheets

Muitos tecidos, como os corações humanos adultos, são incapazes de se regenerar adequadamente após a lesão. 2,3 Estratégias em engenharia de tecidos propor inovações para ajudar o corpo a recuperação e reparação. Por exemplo, as abordagens TE pode ser capaz de atenuar a remodelação cardíaca após infarto do miocárdio (IM) e, possivelmente, aumentar a função cardíaca total a um próximo nível pré-MI normal. 4 Tal como acontece com qualquer tecido funcional, regeneração bem sucedida do tecido cardíaco envolve a entrega dos vários tipos de células com sinais ambientais que favoreçam a integração e sobrevivência do enxerto de células / tecido implantado. Tecidos artificiais devem abordar vários parâmetros, incluindo: sinais solúveis, interações célula-célula, e materiais de matriz avaliados como veículos de entrega, os seus efeitos sobre a sobrevivência da célula, resistência do material, e facilitação de organização célula-tecido. Estudos empregando a injeção direta de células do enxerto apenas ignorar esses elementos essenciais. 2,5,6Um projeto de tecidos combinando esses ingredientes ainda tem de ser desenvolvido. Aqui, apresentamos um exemplo de projetos integrados que utilizam camadas de folhas de células padronizadas com dois tipos distintos de materiais biológicos derivados contendo o tipo de célula para órgãos-alvo e células endoteliais para aumentar a formação de novos vasos no &quot;tecido&quot;. Embora esses estudos concentram-se na geração de tecido cardíaco semelhante, este projeto tecido pode ser aplicado a muitos outros do que o coração com design e material alterações mínimas órgãos, e é destinado a ser um produto off-the-shelf para terapias regenerativas. O protocolo contém cinco etapas detalhadas. Uma temperatura de poli sensível (N -isopropylacrylamide) (PNIPAAm) é usado para placas de cultura de tecidos revestimento. Em seguida, as células são cultivadas de tecido específico sobre a superfície das placas revestidas / superfícies micropattern para formar camadas de células com aderências laterais fortes. Em terceiro lugar, uma matriz de base, é criado para o tecido através da combinação de matriz porosa com Permissi neovascularve hidrogéis e células endoteliais. Finalmente, as folhas de células são levantados a partir dos pratos PNIPAAm revestidos e transferido para o elemento de base, fazendo com que a construção completa.

O diagrama de fluxo (Figura 1) mostra o método geral para fazer o penso multicamadas. Folhas de células são separadas da placa tratada PNIPAAm por baixar a temperatura abaixo de 32 ° C. Em seguida, a camada de células é colocada em cima do hidrogel reticulado contendo as células endoteliais semeadas na matriz fibrosa subjacente (Figura 1). As placas pré-tratados termossensíveis, também podem ser utilizados para criar as camadas de células. Superfícies topológicas especiais ...

Watch this Scientific Journal Video about Tissue Engineering: Construction of a Multicellular 3D Scaffold for the Delivery of Layered Cell Sheets at JoVE.com

Tissue Engineering: Construction of a Multicellular 3D Scaffold for the Delivery of Layered Cell Sheets

For creation of highly organized structures of complex tissue, one must assemble multiple material and cell types into an integrated composite. This combinatorial design incorporates organ-specific layered cell sheets with two distinct biologically-derived materials containing a strong fibrous matrix base, and endothelial cells for enhancing new vessels formation.

Engenharia de Tecidos: Construção de um multicelular 3D andaime para a entrega de camadas celulares Sheets

Many tissues, such as the adult human hearts, are unable to adequately regenerate after damage.2,3 Strategies in tissue engineering propose innovations to ...

tissue-engineering-construction-multicellular-3d-scaffold-for

Research

JoVE Journal

Bioengineering

14.4K visualizações.  University of California, Merced. For creation of highly organized structures of complex tissue, one must assemble multiple material and cell types into an integrated composite. This combinatorial design incorporates organ-specific layered cell sheets with two distinct biologically-derived materials containing a strong fibrous matrix base, and endothelial cells for enhancing new vessels formation.

Vídeo: Tissue Engineering: Construction of a Multicellular 3D Scaffold for the Delivery of Layered Cell Sheets

Postproduction Processing of Electrospun Fibres for Tissue Engineering

Electrospinning is a commonly used and versatile method to produce scaffolds (often biodegradable) for 3D tissue engineering.1, 2, 3 Many tissues in vivo undergo biaxial distension to varying extents such as skin, bladder, pelvic floor and even the hard palate as children grow. In producing scaffolds for these purposes there is a need to develop scaffolds of appropriate biomechanical properties (whether achieved without or with cells) and which are sterile for clinical use. The focus of this paper is not how to establish basic electrospinning parameters (as there is extensive literature on electrospinning) but on how to modify spun scaffolds post production to make them fit for tissue engineering purposes - here thickness, mechanical properties and sterilisation (required for clinical use) are considered and we also describe how cells can be cultured on scaffolds and subjected to biaxial strain to condition them for specific applications.
Electrospinning tends to produce thin sheets; as the electrospinning collector becomes coated with insulating fibres it becomes a poor conductor such that fibres no longer deposit on it. Hence we describe approaches to produce thicker structures by heat or vapour annealing increasing the strength of scaffolds but not necessarily the elasticity. Sequential spinning of scaffolds of different polymers to achieve complex scaffolds is also described. Sterilisation methodologies can adversely affect strength and elasticity of scaffolds. We compare three methods for their effects on the biomechanical properties on electrospun scaffolds of poly lactic-co-glycolic acid (PLGA).
Imaging of cells on scaffolds and assessment of production of extracellular matrix (ECM) proteins by cells on scaffolds is described. Culturing cells on scaffolds in vitro can improve scaffold strength and elasticity but the tissue engineering literature shows that cells often fail to produce appropriate ECM when cultured under static conditions. There are few commercial systems available that allow one to culture cells on scaffolds under dynamic conditioning regimes - one example is the Bose Electroforce 3100 which can be used to exert a conditioning programme on cells in scaffolds held using mechanical grips within a media filled chamber.4 An approach to a budget cell culture bioreactor for controlled distortion in 2 dimensions is described. We show that cells can be induced to produce elastin under these conditions. Finally assessment of the biomechanical properties of processed scaffolds cultured with or without cells is described.

Electrospun scaffolds can be processed post production for tissue engineering applications. Here we describe methods for spinning complex scaffolds (by consecutive spinning), for making thicker scaffolds (by multi-layering using heat or vapour annealing), for achieving sterility (aseptic production or sterilisation post production) and for achieving appropriate biomechanical properties.

Processamento de pós-produção de Fibras electrospun para Engenharia de Tecidos

Electrospinning is a commonly used and versatile method to produce  scaffolds (often biodegradable) for 3D tissue engineering.1, 2, 3 Many tissues in vivo ...

Bioengenharia

Design of a Biaxial Mechanical Loading Bioreactor for Tissue Engineering

We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 &mu;m and a resolution of 20 nm, translating to a positional accuracy of less than 3 &mu;m over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0.15% to 0.25% full scale.

We designed a novel mechanical loading bioreactor that can apply uniaxial or biaxial mechanical strain to a cartilage biocomposite prior to transplantation into an articular cartilage defect.

Projeto de um biorreator Carregando Mecânica Biaxial para Engenharia de Tecidos

We  designed a loading device that is capable of applying uniaxial or biaxial  mechanical strain to a tissue engineered biocomposites fabricated for  ...

Tissue Engineering of a Human 3D in vitro Tumor Test System

Cancer is one of the leading causes of death worldwide. Current therapeutic strategies are predominantly developed in 2D culture systems, which inadequately reflect physiological conditions in vivo. Biological 3D matrices provide cells an environment in which cells can self-organize, allowing the study of tissue organization and cell differentiation. Such scaffolds can be seeded with a mixture of different cell types to study direct 3D cell-cell-interactions. To mimic the 3D complexity of cancer tumors, our group has developed a 3D in vitro tumor test system.	
	Our 3D tissue test system models the in vivo situation of malignant peripheral nerve sheath tumors (MPNSTs), which we established with our decellularized porcine jejunal segment derived biological vascularized scaffold (BioVaSc). In our model, we reseeded a modified BioVaSc matrix with primary fibroblasts, microvascular endothelial cells (mvECs) and the S462 tumor cell line. For static culture, the vascular structure of the BioVaSc is removed and the remaining scaffold is cut open on one side (Small Intestinal Submucosa SIS-Muc). The resulting matrix is then fixed between two metal rings (cell crowns).	
	Another option is to culture the cell-seeded SIS-Muc in a flow bioreactor system that exposes the cells to shear stress. Here, the bioreactor is connected to a peristaltic pump in a self-constructed incubator. A computer regulates the arterial oxygen and nutrient supply via parameters such as blood pressure, temperature, and flow rate. This setup allows for a dynamic culture with either pressure-regulated pulsatile or constant flow.	
	In this study, we could successfully establish both a static and dynamic 3D culture system for MPNSTs. The ability to model cancer tumors in a more natural 3D environment will enable the discovery, testing, and validation of future pharmaceuticals in a human-like model.

Tissue Engineering of a Human 3D in vitro Tumor Test System

Methods to create human 3D tumor tissues as test systems are described. These technologies are based on a decellularized Biological Vascularized Scaffold (BioVaSc), primary human cells and a tumor cell line, which can be cultured under static as well as under dynamic conditions in a flow bioreactor.

Engenharia de Tecidos de um 3D Humano<em&gt; In vitro</em&gt; Sistema de Teste de Tumor

Cancer is one of the leading causes of death worldwide.  Current therapeutic strategies are predominantly developed in 2D culture  systems, which ...

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.

Andaimes auto-relato para cultura de células 3-Dimensional

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

Engineering 3D Cellularized Collagen Gels for Vascular Tissue Regeneration

Synthetic materials are known to initiate clinical complications such as inflammation, stenosis, and infections when implanted as vascular substitutes. Collagen has been extensively used for a wide range of biomedical applications and is considered a valid alternative to synthetic materials due to its inherent biocompatibility (i.e., low antigenicity, inflammation, and cytotoxic responses). However, the limited mechanical properties and the related low hand-ability of collagen gels have hampered their use as scaffold materials for vascular tissue engineering. Therefore, the rationale behind this work was first to engineer cellularized collagen gels into a tubular-shaped geometry and second to enhance smooth muscle cells driven reorganization of collagen matrix to obtain tissues stiff enough to be handled.
The strategy described here is based on the direct assembling of collagen and smooth muscle cells (construct) in a 3D cylindrical geometry with the use of a molding technique. This process requires a maturation period, during which the constructs are cultured in a bioreactor under static conditions (without applied external dynamic mechanical constraints) for 1 or 2 weeks. The &#8220;static bioreactor&#8221; provides a monitored and controlled sterile environment (pH, temperature, gas exchange, nutrient supply and waste removal) to the constructs. During culture period, thickness measurements were performed to evaluate the cells-driven remodeling of the collagen matrix, and glucose consumption and lactate production rates were measured to monitor the cells metabolic activity. Finally, mechanical and viscoelastic properties were assessed for the resulting tubular constructs. To this end, specific protocols and a focused know-how (manipulation, gripping, working in hydrated environment, and so on) were developed to characterize the engineered tissues.

In this work, we present a technique for the rapid fabrication of living vascular tissues by direct culturing of collagen, smooth muscle cells and endothelial cells. In addition, a new protocol for the mechanical characterization of engineered vascular tissues is described.

Engenharia 3D celularizados Colágeno Gel para Vascular Regeneração Tecidual

Synthetic materials are known to initiate clinical complications such as inflammation, stenosis, and infections when implanted as vascular substitutes. ...

Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall

Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to intrinsic parameters within the process allow a high degree of control over scaffold characteristics including fiber diameter, alignment and porosity. By developing scaffolds with similar dimensions and topographies to organ- or tissue-specific extracellular matrices (ECM), micro-environments representative to those that cells are exposed to in situ can be created. 
The airway bronchiole wall, comprised of three main micro-environments, was selected as a model tissue. Using decellularized airway ECM as a guide, we electrospun the non-degradable polymer, polyethylene terephthalate (PET), by three different protocols to produce three individual electrospun scaffolds optimized for epithelial, fibroblast or smooth muscle cell-culture. Using a commercially available bioreactor system, we stably co-cultured the three cell-types to provide an in vitro model of the airway wall over an extended time period.
This model highlights the potential for such methods being employed in in vitro diagnostic studies investigating important inter-cellular cross-talk mechanisms or assessing novel pharmaceutical targets, by providing a relevant platform to allow the culture of fully differentiated adult cells within 3D, tissue-specific environments.

Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall

Advancements in biomaterial technologies enable the development of three-dimensional multi-cell-type constructs. We have developed electrospinning protocols to produce three individual scaffolds to culture the main structural cells of the airway to provide a 3D in vitro model of the airway bronchiole wall.

Adaptação do Processo Electrospinning para fornecer três ambientes únicos para um Tri-camadas<em&gt; In Vitro</em&gt; Modelo da parede das vias aéreas

Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to ...

Construction of Modular Hydrogel Sheets for Micropatterned Macro-scaled 3D Cellular Architecture

Hydrogels can be patterned at the micro-scale using microfluidic or micropatterning technologies to provide an in vivo-like three-dimensional (3D) tissue geometry. The resulting 3D hydrogel-based cellular constructs have been introduced as an alternative to animal experiments for advanced biological studies, pharmacological assays and organ transplant applications. Although hydrogel-based particles and fibers can be easily fabricated, it is difficult to manipulate them for tissue reconstruction. In this video, we describe a fabrication method for micropatterned alginate hydrogel sheets, together with their assembly to form a macro-scale 3D cell culture system with a controlled cellular microenvironment. Using a mist form of the calcium gelling agent, thin hydrogel sheets are easily generated with a thickness in the range of 100 - 200 &#181;m, and with precise micropatterns. Cells can then be cultured with the geometric guidance of the hydrogel sheets in freestanding conditions. Furthermore, the hydrogel sheets can be readily manipulated using a micropipette with an end-cut tip, and can be assembled into multi-layered structures by stacking them using a patterned polydimethylsiloxane (PDMS) frame. These modular hydrogel sheets, which can be fabricated using a facile process, have potential applications of in vitro drug assays and biological studies, including functional studies of micro- and macrostructure and tissue reconstruction.

We describe the fabrication of micropatterned hydrogel sheets using a simple process, which can be assembled and manipulated in a freestanding form. Using these modular hydrogel sheets, a simple macro-scaled 3D cell culture system can be generated with a controlled cellular microenvironment.

Construção de Fichas de hidrogel modular para micropadronadas Macro-escalado 3D Cellular Arquitetura

Hydrogels can be patterned at the micro-scale using microfluidic or micropatterning technologies to provide an in vivo-like three-dimensional (3D) tissue ...

Fabrication of Inverted Colloidal Crystal Poly(ethylene glycol) Scaffold: A Three-dimensional Cell Culture Platform for Liver Tissue Engineering

The ability to maintain hepatocyte function in vitro, for the purpose of testing xenobiotics&#39; cytotoxicity, studying virus infection and developing drugs targeted at the liver, requires a platform in which cells receive proper biochemical and mechanical cues. Recent liver tissue engineering systems have employed three-dimensional (3D) scaffolds composed of synthetic or natural hydrogels, given their high water retention and their ability to provide the mechanical stimuli needed by the cells. There has been growing interest in the inverted colloidal crystal (ICC) scaffold, a recent development, which allows high spatial organization, homotypic and heterotypic cell interaction, as well as cell-extracellular matrix (ECM) interaction. Herein, we describe a protocol to fabricate the ICC scaffold using poly (ethylene glycol) diacrylate (PEGDA) and the particle leaching method. Briefly, a lattice is made from microsphere particles, after which a pre-polymer solution is added, properly polymerized, and the particles are then removed, or leached, using an organic solvent (e.g., tetrahydrofuran). The dissolution of the lattice results in a highly porous scaffold with controlled pore sizes and interconnectivities that allow media to reach cells more easily. This unique structure allows high surface area for the cells to adhere to as well as easy communication between pores, and the ability to coat the PEGDA ICC scaffold with proteins also shows a marked effect on cell performance. We analyze the morphology of the scaffold as well as the hepatocarcinoma cell (Huh-7.5) behavior in terms of viability and function to explore the effect of ICC structure and ECM coatings. Overall, this paper provides a detailed protocol of an emerging scaffold that has wide applications in tissue engineering, especially liver tissue engineering.

Fabrication of Inverted Colloidal Crystal Polyethylene glycol Scaffold: A Three-dimensional Cell Culture Platform for Liver Tissue Engineering

This manuscript presents a detailed protocol for the fabrication of an emerging three-dimensional hepatocyte culture platform, the inverted colloidal crystal scaffold, and the concomitant techniques to assess hepatocyte behavior. The size-controllable pores, interconnectivity and ability to conjugate extracellular matrix proteins to the poly(ethylene glycol) (PEG) scaffold enhance Huh-7.5 cell performance.

Fabricação de Inverted coloidal de cristal poli (etileno-glicol) Andaime: Uma Plataforma Cultura celular tridimensional para Liver Engenharia de Tecidos

The ability to maintain hepatocyte function in vitro, for the purpose of testing xenobiotics&#39; cytotoxicity, studying virus infection and developing ...

Fabrication of Extracellular Matrix-derived Foams and Microcarriers as Tissue-specific Cell Culture and Delivery Platforms

Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus of this article is on the methods for fabricating ECM-derived porous foams and microcarriers for use as biologically-relevant substrates in advanced 3D in vitro cell culture models or as pro-regenerative scaffolds and cell delivery systems for tissue engineering and regenerative medicine. Using decellularized tissues or purified insoluble collagen as a starting material, the techniques can be applied to synthesize a broad array of tissue-specific bioscaffolds with customizable geometries. The approach involves mechanical processing and mild enzymatic digestion to yield an ECM suspension that is used to fabricate the three-dimensional foams or microcarriers through controlled freezing and lyophilization procedures. These pure ECM-derived scaffolds are highly porous, yet stable without the need for chemical crosslinking agents or other additives that may negatively impact cell function. The scaffold properties can be tuned to some extent by varying factors such as the ECM suspension concentration, mechanical processing methods, or synthesis conditions. In general, the scaffolds are robust and easy to handle, and can be processed as tissues for most standard biological assays, providing a versatile and user-friendly 3D cell culture platform that mimics the native ECM composition. Overall, these straightforward methods for fabricating customized ECM-derived foams and microcarriers may be of interest to both biologists and biomedical engineers as tissue-specific cell-instructive platforms for in vitro and in vivo applications.

The tissue-specific extracellular matrix (ECM) is a key mediator of cell function. This article describes methods for synthesizing pure ECM-derived foams and microcarriers that are stable in culture without the need for chemical crosslinking for applications in advanced 3D in vitro cell culture models or as pro-regenerative bioscaffolds.

Fabricação de espumas de Matriz Extracelular derivados e Microcarregadores como cultura celular de tecidos específicos e plataformas de entrega

Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus ...

Bioprinting of Cartilage and Skin Tissue Analogs Utilizing a Novel Passive Mixing Unit Technique for Bioink Precellularization

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both cartilage and skin analogs were fabricated after bioink pre-cellularization utilizing a novel passive mixing unit technique. This technique was developed with the aim to simplify the steps involved in the mixing of a cell suspension into a highly viscous bioink. The resolution of filaments deposited through bioprinting necessitates the assurance of uniformity in cell distribution prior to printing to avoid the deposition of regions without cells or retention of large cell clumps that can clog the needle. We demonstrate the ability to rapidly blend a cell suspension with a bioink prior to bioprinting of both cartilage and skin analogs. Both tissue analogs could be cultured for up to 4 weeks. Histological analysis demonstrated both cell viability and deposition of tissue specific extracellular matrix (ECM) markers such as glycosaminoglycans (GAGs) and collagen I respectively.

Cartilage and skin analogs were bioprinted using a nanocellulose-alginate based bioink. The bioinks were cellularized prior to printing via a single step passive mixing unit. The constructs were demonstrated to be uniformly cellularized, have high viability, and exhibit favorable markers of differentiation.

Bioprinting da cartilagem e Analogs de tecido de pele utilizando um romance passiva unidade técnica de mistura para Bioink Precellularization

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both ...