Cette étude est soutenue financièrement par ZonMw dans le cadre du programme LSH 2Treat (436001003) et de la Dutch Kidney Foundation (14a2d507). N.A.K. reconnaît le soutien du Conseil européen de la recherche (851960). Nous remercions le programme gravitation « Materials Driven Regeneration », financé par l’Organisation néerlandaise pour la recherche scientifique (024.003.013).

Les auteurs n’ont rien à divulguer.

Le bioréacteur décrit ici permet l’évaluation systématique des contributions de l’individu et des effets combinés de la contrainte de cisaillement et de l’étirement cyclique sur l’inflammation et la régénération tissulaire dans les échafaudages tubulaires résorbables. Cette approche permet également d’effectuer une grande variété d’analyses sur des constructions vasculaires, comme l’illustre la section des résultats représentatifs. Ces résultats montrent l’impact distinctif des différent...

L’ingénierie tissulaire cardiovasculaire (TE) est poursuivie comme une option de traitement alternative aux prothèses cardiovasculaires permanentes actuellement utilisées (par exemple, greffes vasculaires, remplacements de valves cardiaques), qui sont sous-optimales pour de grandes cohortes de patients1,2,3,4. Les applications très recherchées comprennent les greffes vasculaires d’ingénierie tissulaire (TEVG)5,6 et les valves cardiaques (TEHV)7,8. Le plus souvent, les méthodologies d’ÉT cardiovasculaire utilisent des biomatériaux résorbables (naturels ou synthétiques) qui servent d’échafaudage instructif pour la formation du nouveau tissu. La formation de nouveaux tissus peut soit être conçue complètement in vitro, en ensemencant l’échafaudage avec des cellules et en le cultivant dans un bioréacteur avant l’implantation (TE in vitro)9,10,11, soit directement in situ, dans laquelle l’échafaudage synthétique est implanté sans pré-culture afin d’induire la formation de nouveaux tissus directement dans le corps (TE in situ)12,13,14. Pour les approches cardiovasculaires TE in vitro et in situ, la régénération fonctionnelle réussie dépend principalement de la réponse immunitaire de l’hôte à la construction implantée et de la charge biomécanique appropriée.
L’importance de la charge biomécanique pour les TE cardiovasculaires est bien reconnue15. Dans le cas des implants cardiovasculaires, les cellules qui peuplent l’échafaudage sont exposées à des contraintes d’étirement et de cisaillement cycliques résultant de l’environnement hémodynamique. De nombreuses études ont rapporté l’effet stimulant de l’étirement (cyclique) sur la formation de composants de la matrice,tels que le collagène16,17,18,19, glycosaminoglycanes (GAGs)20, etl’élastine 21,22, par divers types de cellules. Par exemple, Huang et al. ont démontré que l’étirement biaxial élevait le dépôt et l’organisation du collagène et de l’élastine dans les TEVG in vitro en utilisant un bioréacteur vasculaire23. Bien que l’accent soit généralement mis sur l’étirement en tant que charge dominante, ces études utilisent souvent des bioréacteurs pilotés par écoulement dans lesquels l’échantillon est également exposé à un écoulement de cisaillement. Bien que l’on sache relativement peu de choses sur l’influence isolée des contraintes de cisaillement sur la formation des tissus et l’inflammation en 3D, certaines données sont disponibles. Par exemple, Hinderer et al. et Eoh et al. ont démontré que le flux de cisaillement, en plus d’une microstructure d’échafaudage 3D, était important pour la formation d’élastine mature par les cellules musculaires lisses vasculaires humaines dans un système de modèle in vitro24,25. Dans l’ensemble, ces résultats illustrent la pertinence de l’étirement cyclique et du stress de cisaillement pour l’ET cardiovasculaire.
Un autre déterminant important du succès ou de l’échec des implants TE est la réponse immunitaire de l’hôte au greffon implanté26. Ceci est particulièrement important pour les stratégies TE in situ axées sur les matériaux, qui reposent en fait sur la réponse inflammatoire aiguë à l’échafaudage pour lancer les processus ultérieurs d’afflux cellulaire et de formation et de remodelage des tissus endogènes27. Le macrophage est un initiateur critique de la régénération fonctionnelle des tissus, ce qui a été démontré par de multiples études28,29,30. Analogue à la cicatrisation des plaies, la régénération des tissus est régie par la signalisation paracrine entre les macrophages et les cellules productrices de tissus telles que les fibroblastes et les myofibroblastes31,32,33. En plus de coordonner les nouveaux dépôts tissulaires, les macrophages sont impliqués dans la résorption active des échafaudages étrangers34,35. A ce titre, la réponse in vitro des macrophages à un biomatériau a été identifiée comme un paramètre prédictif du succès in vivo des implants36,37,38.
La réponse des macrophages à un échafaudage implanté dépend des caractéristiques de conception de l’échafaudage telles que la composition du matériau et la microstructure35,39,40. En plus des propriétés de l’échafaudage, la réponse des macrophages à un échafaudage et leur diaphonie avec les myofibroblastes sont également affectées par les charges hémodynamiques. Par exemple, l’étirement cyclique s’est avéré être un modulateur important du phénotype des macrophages41,42,43,44 et de la sécrétion de cytokines 43 ,44,45,46 dans les échafaudages électrospunés 3D. En utilisant un système de co-culture de macrophages et de cellules musculaires lisses vasculaires, Battiston et al. ont démontré que la présence de macrophages entraînait une augmentation des niveaux d’élastine et de GAG et que des niveaux modérés d’étirement cyclique (1,07-1,10) stimulaient le dépôt de collagène I et d’élastine47. Dans des travaux antérieurs, nous avons démontré que le stress de cisaillement est un déterminant important pour le recrutement des monocytes dans les échafaudages électro filés3D 48,49, et que le stress de cisaillement et l’étirement cyclique ont un impact sur la signalisation paracrine entre les monocytes humains et les cellules stromales mésenchymateuses50. Fahy et al. ont démontré que le flux de cisaillement augmentait la sécrétion de cytokines pro-inflammatoires par les monocytes humains51.
Pris ensemble, les preuves ci-dessus montrent qu’une compréhension et un contrôle adéquats des charges hémodynamiques sont cruciaux pour l’ÉT cardiovasculaire, et qu’il est important de prendre en compte la réponse inflammatoire pour y parvenir. De nombreux bioréacteurs ont été décrits précédemment pour la culture in vitro52,53,54,55,56,57,58 ou ex vivo59,60,61 de tissus cardiovasculaires. Cependant, tous ces systèmes sont conçus pour imiter autant que possible les conditions physiologiques de charge hémodynamique. Bien que cela soit très utile dans le but de créer des tissus cardiovasculaires in vitro ou de maintenir des cultures ex vivo, de tels systèmes ne permettent pas d’études systématiques sur les effets individuels d’indices individuels. En effet, l’application de la contrainte d’étirement et de cisaillement cyclique dans ces bioréacteurs est entraînée par le même écoulement sous pression, qui les lie intrinsèquement. Alors que des microsystèmes permettant une manipulation mécanique multi-signaux précise ont été décrits pour les substrats2D 62 ou les configurations d’hydrogel 3D63,64, de telles configurations ne permettent pas l’incorporation d’échafaudages de biomatériaux élastomères 3D.
Nous présentons ici l’application d’un système de bioréacteur tubulaire qui permet de manière unique le découplage de la contrainte de cisaillement et de l’étirement cyclique et aide à étudier mécaniquement leurs effets individuels et combinés. Ce système permet de tester une grande variété de greffes vasculaires d’ingénierie tissulaire (par exemple, origine synthétique ou naturelle, micro-architecture différente, porosités diverses). Pour découpler efficacement l’application de la contrainte de cisaillement et de l’étirement, les concepts clés utilisés par le bioréacteur sont (1) la séparation du contrôle de la contrainte de cisaillement et de l’étirement à l’aide de systèmes de pompage distincts et (2) la stimulation des échafaudages de manière « à l’envers » avec des dimensions pilotées par calcul. L’écoulement est appliqué sur la surface extérieure de l’échafaudage tubulaire à l’utilisation d’une pompe à débit, tandis que l’étirement circonférentiel de l’échafaudage est induit par l’expansion d’un tube en silicone sur lequel l’échafaudage est monté à l’utilisation d’une pompe de contrainte séparée. Les dimensions du tube en silicone et du tube en verre qui contient la construction sont soigneusement choisies et validées à l’aide de simulations computationnelles de la dynamique des fluides, afin de s’assurer que la contrainte de cisaillement sur l’échafaudage (due à l’écoulement) et l’étirement circonférentiel (dû à l’expansion du tube) ne s’affectent pas de manière significative. Cette conception à l’envers a plusieurs justifications pratiques. Si l’étirement est appliqué par la pression du fluide luminal (similaire à la charge physiologique), il nécessite intrinsèquement que le plan d’échantillonnage soit exempt de fuites. De plus, la pression requise pour étirer l’échantillon serait entièrement déterminée par la rigidité de l’échantillon, qui peut varier d’un échantillon à l’autre et à l’intérieur d’un échantillon au fil du temps, ce qui rend difficile le contrôle de l’étirement. Ce bioréacteur monte la greffe de tissu autour d’un tube en silicone et permet l’application de contraintes de cisaillement de la paroi (WSS) sur la paroi externe de la greffe et met la greffe sous pression de l’intérieur. De cette façon, des conditions de charge égales entre les échantillons et à l’intérieur des échantillons au fil du temps peuvent être assurées, et de plus, les échantillons sont autorisés à fuir, comme c’est le cas pour les échafaudages vasculaires poreux19. Ce bioréacteur à l’envers est spécifiquement destiné à des études systématiques sur les effets du cisaillement et / ou de l’étirement, plutôt qu’à l’ingénierie d’un vaisseau sanguin de type natif in vitro, pour lequel les configurations de bioréacteur vasculaire traditionnelles sont plus appropriées. Voir la figure 1A–B pour les dessins de conception du bioréacteur et le tableau 1 correspondant pour une description fonctionnelle et une justification des principaux composants du bioréacteur.
L’utilisation du bioréacteur est démontrée sur la base d’une série d’études récentes de notre groupe dans lesquelles nous avons étudié les influences individuelles et combinées du stress de cisaillement et de l’étirement cyclique sur l’inflammation et la formation de tissus dans des échafaudages électrospunables résorbables pour les tissus cardiovasculaires in situ19,43,44. À cette fin, nous avons utilisé des macrophages humains et des myofibroblastes en monoculture ou en co-culture pour simuler les différentes phases de la cascade régénérative in situ. Nous avons démontré que la sécrétion de cytokines par les macrophages humains est nettement affectée par l’étirement cyclique et la contrainte de cisaillement, affectant le dépôt et l’organisation de la matrice par les myofibroblastes humains dans ces échafaudages, à la fois via la signalisation paracrine et le contact direct19,43,44. Notamment, ces études ont révélé que dans le cas de l’application combinée de contrainte de cisaillement et d’étirement, les effets sur la formation tissulaire et l’inflammation sont soit dominés par l’une des deux charges, soit il existe des effets synergiques des deux charges. Ces résultats illustrent la pertinence du découplage des deux charges pour mieux comprendre la contribution de l’environnement mécanique sur les processus TE. Cette compréhension peut être appliquée pour optimiser systématiquement les paramètres de conception des échafaudages dans les régimes de charge hémodynamique pertinents. En outre, les données mécanistes de ces environnements bien contrôlés peuvent servir d’entrée pour des modèles numériques en cours de développement pour prédire l’évolution du remodelage tissulaire in situ, comme cela a été récemment rapporté pour les TEVG65 ou TEHV66,afin d’améliorer encore la capacité prédictive.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >advanced Dulbecco&#8217;s modified EagleMedium (aDMEM)</td>
			<td >Gibco</td>
			<td >12491-015</td>
			<td >cell culture medium for fibroblasts</td>
		</tr>
		<tr >
			<td >Aqua Stabil</td>
			<td >Julabo</td>
			<td >8940012</td>
			<td >prevent microorganism growth in bioreactor-hydraulic reservoir</td>
		</tr>
		<tr >
			<td >Bovine fibrinogen</td>
			<td >Sigma</td>
			<td >F8630</td>
			<td >to prepare fibrinogen gel to seed the cells on the electrospun scaffold</td>
		</tr>
		<tr >
			<td >Bovine thrombin</td>
			<td >Sigma</td>
			<td >T4648</td>
			<td >to prepare fibrinogen gel to seed the cells on the electrospun scaffold</td>
		</tr>
		<tr >
			<td >Centrifuge</td>
			<td >Eppendorf</td>
			<td >5804</td>
			<td >to spin down cells and conditioned medium</td>
		</tr>
		<tr >
			<td >Clamp scissor - &#34;kelly forceps&#34;</td>
			<td >Almedic</td>
			<td >P-422</td>
			<td >clamp the silicone tubing and apply pre-stretch to the scaffold so the scaffold can be sutured into the engraved groove (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >CO2 cell culture incubators</td>
			<td >Sanyo</td>
			<td >MCO-170AIC-PE</td>
			<td >for cell culturing</td>
		</tr>
		<tr >
			<td >Compressed air reservoir</td>
			<td >Festo</td>
			<td >CRVZS-5</td>
			<td >smoothing air pressure fluctuations and create time delays for pressure build-up</td>
		</tr>
		<tr >
			<td >Custom Matlab script to calculate the maximum stretches</td>
			<td >Matlab</td>
			<td >R2017. The Mathworks, Natick, MA</td>
			<td >calculate the minimum and maximum outer diameter of the electrospun scaffold</td>
		</tr>
		<tr >
			<td >Data acquisition board</td>
			<td >National Instruments</td>
			<td >BNC-2090</td>
			<td >data processing in between amplifier system and computer</td>
		</tr>
		<tr >
			<td >Ethanol</td>
			<td >VWR</td>
			<td >VWRK4096-9005</td>
			<td >to keep sterile working conditions</td>
		</tr>
		<tr >
			<td >Fetal bovine calf serum (FBS)</td>
			<td >Greiner</td>
			<td >758087</td>
			<td >cell culture medium supplement; serum-supplement</td>
		</tr>
		<tr >
			<td >Flow culture chamber compartments, consisting of a pressure conduit with engraved grooves and small holes to apply pressure on silicone tubing, a screw thread, nose cone, top compartment with flow inlet and bottom compartment flow outlet, adapter bushing</td>
			<td >Custom made, Department of Biomedical Engineering, Eindhoven University of Technology</td>
			<td >n.a.</td>
			<td >flow culture chamber compartments (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >Glass Pasteur pipet</td>
			<td >Assistant</td>
			<td >HE40567002</td>
			<td >apply vacuum on electrospun scaffold (autoclave at step 1)</td>
		</tr>
		<tr >
			<td >Glass tubes of the flow culture chamber</td>
			<td >Custon made, Equipment &#38; Prototype Center, Eindhoven University of Technology</td>
			<td >n.a.</td>
			<td >part of the flow culture chamber (clean and store in 70% ethanol, at step 1 and 7)</td>
		</tr>
		<tr >
			<td >GlutaMax</td>
			<td >Gibco</td>
			<td >35050061</td>
			<td >cell culture medium amino acid supplement, minimizes ammonia build-up</td>
		</tr>
		<tr >
			<td >High speed camera</td>
			<td >MotionScope</td>
			<td >M-5</td>
			<td >to monitor the stretch during culture; time-lapse photographs of the scaffolds are captured at a frequency of 30 Hz for 6 sec (i.e. 3 stretch cycles)</td>
		</tr>
		<tr >
			<td >High speed camera lens - Micro-NIKKOR 55mm f/2.8 - lens</td>
			<td >Nikon</td>
			<td >JAA616AB</td>
			<td >to monitor the stretch during culture; time-lapse photographs of the scaffolds are captured at a frequency of 30 Hz for 6 sec (i.e. 3 stretch cycles)</td>
		</tr>
		<tr >
			<td >Hose clip</td>
			<td >ibidi GmbH</td>
			<td >10821</td>
			<td >block medium flow (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >Hydraulic reservoir with 8 screw threads for 8 flow culture chambers</td>
			<td >Custom made, Department of Biomedical Engineering, Eindhoven University of Technology</td>
			<td >n.a.</td>
			<td >to apply pressure to the silicone mounted constructs (clean outside with a paper tissue with 70% ethanol, rinse reservoir with 70% ethanol followed by demi water, at step 1 and 7)</td>
		</tr>
		<tr >
			<td >Ibidi pump system (8x) including ibidi pump, PumpControl software, fluidic unit, perfusion set (medium tubing), air pressure tubing, drying bottles with orange silica beads</td>
			<td >ibidi GmbH</td>
			<td >10902</td>
			<td >set up used to control the flow in the flow culture chambers. Note 1: the ibidi pumps were modified by the manufacturer to enable 200 mbar capacity. Note 2: can be replaced by pump system of other manufacturer, as long as same flow regimes can be applied.</td>
		</tr>
		<tr >
			<td >Knives (no.10 sterile blades, individual foil pack) and scalpel handle (stainless steel, individually wrapped)</td>
			<td >Swann Morton</td>
			<td >0301; 0933</td>
			<td >to cut the silicone tubing in the correct size for the scaffold and to cut the suture material</td>
		</tr>
		<tr >
			<td >LabVIEW Software</td>
			<td >National Instruments</td>
			<td >version 2018</td>
			<td >to control the stretch applied to the scaffolds</td>
		</tr>
		<tr >
			<td >Laminar flow biosafety cabinet with UV light</td>
			<td >Labconco</td>
			<td >302310001</td>
			<td >to ensure sterile working conditions. The UV is used to decontaminate everything that cannot be autoclaved, or touched after autoclaving</td>
		</tr>
		<tr >
			<td >Large and small petri dishes</td>
			<td >Greiner</td>
			<td >664-160</td>
			<td >for sterile working conditions</td>
		</tr>
		<tr >
			<td >L-ascorbic acid 2-phosphate (vitamin C)</td>
			<td >Sigma</td>
			<td >A8960</td>
			<td >cell culture medium supplement, important for collagen production</td>
		</tr>
		<tr >
			<td >LED light cold source KL2500</td>
			<td >Zeiss</td>
			<td >Schott AG</td>
			<td >to aid in visualization for the time lapse of the scaffolds during monitoring of the stretch</td>
		</tr>
		<tr >
			<td >Luer (female and male) locks and connectors, white luer caps</td>
			<td >ibidi GmbH</td>
			<td >various, see (https://ibidi.com/26-flow-accessories)</td>
			<td >to close or connect parts of the bioreactor and the ibidi pump (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >Measuring amplifier (PICAS)</td>
			<td >PEEKEL instruments B.V.</td>
			<td >n.a.</td>
			<td >to amplify the signal from the pressure sensor and feedback to LabView</td>
		</tr>
		<tr >
			<td >Medium reservoir (large syringes 60 mL) and reservoir holders</td>
			<td >ibidi GmbH</td>
			<td >10974</td>
			<td >medium reservoir (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >Medium tubing with 4.25 mm outer diameter and 1 mm inner diameter</td>
			<td >Rubber BV</td>
			<td >1805</td>
			<td >to allow for a larger flow rate, the ibidi medium tubing with larger diameter is used. Note: the part of medium tubing guided through the fluidic unit valves are the same as the default ibidi medium tubing</td>
		</tr>
		<tr >
			<td >Motion Studio Software</td>
			<td >Idtvision</td>
			<td >2.15.00</td>
			<td >to make the high speed time lapse images for stretch monitoring</td>
		</tr>
		<tr >
			<td >Needle (19G)</td>
			<td >BD Microlance</td>
			<td >301700</td>
			<td >together with thin flexible tubing used to fill the hydraulic reservoir with ultrapure water without adding air bubbles</td>
		</tr>
		<tr >
			<td >Needle driver</td>
			<td >Adson</td>
			<td >2429218</td>
			<td >to handle the needle of the nylon suture through the silicone tube (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >Paper tissues</td>
			<td >Kleenex</td>
			<td >38044001</td>
			<td >for cleaning of the equipment with 70% ethanol</td>
		</tr>
		<tr >
			<td >Parafilm</td>
			<td >Sigma</td>
			<td >P7793-1EA</td>
			<td >quick fix if leakage occurs</td>
		</tr>
		<tr >
			<td >Penicillin/streptomycin (P/S)</td>
			<td >Lonza</td>
			<td >DE17-602E</td>
			<td >cell culture medium supplement; prevent bacterial contamination</td>
		</tr>
		<tr >
			<td >Phosphate Buffered Saline (PBS)</td>
			<td >Sigma</td>
			<td >P4417-100TAB</td>
			<td >for storage and washing steps (autoclave at step 1)</td>
		</tr>
		<tr >
			<td >Plastic containers (60 mL) with red screw caps</td>
			<td >Greiner</td>
			<td >206202</td>
			<td >to prepare the fibrinogen solution</td>
		</tr>
		<tr >
			<td >Pneumatic cylinder</td>
			<td >Festo</td>
			<td >AEVC-20-10-I-P</td>
			<td >to actuate the Teflon bellow (clean with a paper tissue with 70% ethanol at step 1 and 7)</td>
		</tr>
		<tr >
			<td >Polycaprolactone bisurea (PCL-BU) tubular scaffolds (3 mm inner diameter, 200 &#181;m wall thickness, 20 mm length)</td>
			<td >SyMO-Chem, Eindhoven, The Netherlands</td>
			<td >n.a.</td>
			<td >produced using electrospinning from 15% (w/w) chloroform (Sigma; 372978) polymer solutions. See Van Haaften et al Tissue Engineering Part C (2018) for more details</td>
		</tr>
		<tr >
			<td >Pressure conduit without holes (for static control)</td>
			<td >Custom made, Department of Biomedical Engineering, Eindhoven University of Technology</td>
			<td >n.a.</td>
			<td >to mount electrospun tubes on silicon tubing (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >Pressure sensor and transducer</td>
			<td >BD</td>
			<td >TC-XX and P 10 EZ</td>
			<td >the air pressure going to the pneumatic actuated pump is raised until it reaches the set pressure</td>
		</tr>
		<tr >
			<td >Proportional air pressure control valve and pressure sensor</td>
			<td >Festo</td>
			<td >MPPES-3-1/8-2-010, 159596</td>
			<td >provides compressed air to the pneumatic actuated pump</td>
		</tr>
		<tr >
			<td >Roswell Park Memorial Institute 1640 (RPMI-1640)</td>
			<td >Gibco</td>
			<td >A1049101</td>
			<td >cell culture medium for monocyte/macrophage</td>
		</tr>
		<tr >
			<td >Safe lock Eppendorf tubes (1.5 mL)</td>
			<td >Eppendorf</td>
			<td >30120086</td>
			<td >multiple applications (autoclave at step 1)</td>
		</tr>
		<tr >
			<td >Sodium dodecyl sulfate solution 20%</td>
			<td >Sigma</td>
			<td >5030</td>
			<td >Used to clean materials, at a concentration of 0.1%.&#160;&#160;</td>
		</tr>
		<tr >
			<td >Silicone O-rings</td>
			<td >Technirub</td>
			<td >1250S</td>
			<td >to prevent leakage (autoclave at step 1, step 7)</td>
		</tr>
		<tr >
			<td >Silicone tubing (2.8 mm outer diameter, 400 um wall thickness)</td>
			<td >Rubber BV</td>
			<td >1805</td>
			<td >to mount the electrospun tubes on the pressure conduits (autoclave at step 1)</td>
		</tr>
		<tr >
			<td >Sterile tube (15 mL)</td>
			<td >Falcon</td>
			<td >352095</td>
			<td >multiple applications</td>
		</tr>
		<tr >
			<td >Suture, 5-0 prolene with pre-attached taper point needle</td>
			<td >Ethicon, Johnson&#38;Johnson</td>
			<td >EH7404H</td>
			<td >Prolene suture wire 5-0 (75cm length, TF taper point needle, 1/2 circle, 13 mm needle length)</td>
		</tr>
		<tr >
			<td >Syringe (24 mL)</td>
			<td >B. Braun Melsungen AG</td>
			<td >2057932</td>
			<td >to add the ultrapure water or medium to the hydraulic reservoir or flow culture chamber</td>
		</tr>
		<tr >
			<td >Syringe filter (0.2 &#181;m)</td>
			<td >Satorius</td>
			<td >17597-K</td>
			<td >to filter the fibrinogen solution</td>
		</tr>
		<tr >
			<td >T150 cell culture flask with filter cap</td>
			<td >Nunc</td>
			<td >178983</td>
			<td >to degas culture medium</td>
		</tr>
		<tr >
			<td >T75 Cell culture flask with filter cap</td>
			<td >Nunc</td>
			<td >156499</td>
			<td >to culture static control samples</td>
		</tr>
		<tr >
			<td >Teflon bellow</td>
			<td >Custom made, Department of Biomedical Engineering, Eindhoven University of Technology</td>
			<td >n.a.</td>
			<td >to load the hydraulic reservoir (clean outside with a paper tissue with 70% ethanol at step 1 and 7)</td>
		</tr>
		<tr >
			<td >Tray (stainless steel)</td>
			<td >PolarWare</td>
			<td >15-248</td>
			<td >for easy transport of the fluidic culture chambers and the bioreactor from incubator to laminar flow cabinet and back (clean with a paper tissue with 70% ethanol before and after use)</td>
		</tr>
		<tr >
			<td >Tweezers</td>
			<td >Wironit</td>
			<td >4910</td>
			<td >sterile handling of individual parts (autoclave at step 1 and 7)</td>
		</tr>
		<tr >
			<td >Ultrapure water</td>
			<td >Stakpure</td>
			<td >Omniapure UV 18200002</td>
			<td >to correct for medium evaporation, mixed with aqua stabil mixed and used as hydraulic fluid. (autoclave ultrapure water at step 1)</td>
		</tr>
		<tr >
			<td >UV light</td>
			<td >Philips</td>
			<td >TUV 30W/G30 T8</td>
			<td >for decontamination of grafts and bioreactor parts before seeding</td>
		</tr>
	</tbody>
</table>

a multi-cue bioreactor to evaluate the inflammatory and regenerative capacity of biomaterials under flow and stretch

L’utilisation de biomatériaux résorbables pour induire la régénération directement dans le corps est une stratégie attrayante d’un point de vue translationnel. Ces matériaux induisent une réponse inflammatoire lors de l’implantation, qui est le moteur de la résorption ultérieure du matériau et de la régénération de nouveaux tissus. Cette stratégie, également connue sous le nom d’ingénierie tissulaire in situ, est poursuivie pour obtenir des remplacements cardiovasculaires tels que des greffes vasculaires modifiées par des tissus. Les processus inflammatoires et régénératifs sont déterminés par les signaux biomécaniques locaux sur l’échafaudage (c.-à-d. contrainte d’étirement et de cisaillement). Ici, nous décrivons en détail l’utilisation d’un bioréacteur développé sur mesure qui permet de manière unique le découplage de la contrainte d’étirement et de cisaillement sur un échafaudage tubulaire. Cela permet l’évaluation systématique et standardisée de la capacité inflammatoire et régénératrice des échafaudages tubulaires sous l’influence de charges mécaniques bien contrôlées, que nous démontrons sur la base d’une expérience de co-culture dynamique utilisant des macrophages et des myofibroblastes humains. Les principales étapes pratiques de cette approche – la construction et la mise en place du bioréacteur, la préparation des échafaudages et de l’ensemencement des cellules, l’application et le maintien de l’écoulement d’étirement et de cisaillement, et la récolte d’échantillons pour analyse – sont discutées en détail.

Ce bioréacteur a été développé pour étudier les effets individuels et combinés du stress de cisaillement et de l’étirement cyclique sur la croissance et le remodelage des tissus vasculaires dans les échafaudages de biomatériaux 3D. La conception du bioréacteur permet de cultiver jusqu’à huit constructions vasculaires dans diverses conditions de charge(Figure 1A). Les constructions vasculaires sont positionnées dans une chambre de culture en flux(Figure 1...

Watch this Scientific Journal Video about A Multi-Cue Bioreactor to Evaluate the Inflammatory and Regenerative Capacity of Biomaterials under Flow and Stretch at JoVE.com

A Multi-Cue Bioreactor to Evaluate the Inflammatory and Regenerative Capacity of Biomaterials under Flow and Stretch

L’objectif de ce protocole est d’exécuter une co-culture dynamique de macrophages humains et de myofibroblastes dans des échafaudages tubulaires électrospunés pour étudier la régénération tissulaire entraînée par les matériaux, à l’aide d’un bioréacteur qui permet le découplage de la contrainte de cisaillement et de l’étirement cyclique.

Un bioréacteur multi-cue pour évaluer la capacité inflammatoire et régénératrice des biomatériaux sous écoulement et étirement

The use of resorbable biomaterials to induce regeneration directly in the body is an attractive strategy from a translational perspective. Such materials ...

a-multi-cue-bioreactor-to-evaluate-inflammatory-regenerative-capacity

Research

JoVE Journal

Engineering

5.4K vues.  Eindhoven University of Technology. L’objectif de ce protocole est d’exécuter une co-culture dynamique de macrophages humains et de myofibroblastes dans des échafaudages tubulaires électrospunés pour étudier la régénération tissulaire entraînée par les matériaux, à l’aide d’un bioréacteur qui permet le découplage de la contrainte de cisaillement et de l’étirement cyclique.

Vidéo: A Multi-Cue Bioreactor to Evaluate the Inflammatory and Regenerative Capacity of Biomaterials under Flow and Stretch

Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering

A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is presented. The SANS shear cell consists of a concentric cylinder Couette geometry that is sealed and rotating about a horizontal axis so that the vorticity direction of the flow field is aligned with the neutron beam enabling scattering from the 1-2 plane of shear (velocity-velocity gradient, respectively). This approach is an advance over previous shear cell sample environments as there is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. Flow-instabilities, such as shear banding, can also be studied by spatially resolved measurements. This is accomplished in this sample environment by using a narrow aperture for the neutron beam and scanning along the velocity gradient direction. Time resolved experiments, such as flow start-ups and large amplitude oscillatory shear flow are also possible by synchronization of the shear motion and time-resolved detection of scattered neutrons. Representative results using the methods outlined here demonstrate the useful nature of spatial resolution for measuring the microstructure of a wormlike micelle solution that exhibits shear banding, a phenomenon that can only be investigated by resolving the structure along the velocity gradient direction. Finally, potential improvements to the current design are discussed along with suggestions for supplementary experiments as motivation for future experiments on a broad range of complex fluids in a variety of shear motions.

A shear cell is developed for small-angle neutron scattering measurements in the velocity-velocity gradient plane of shear and is used to characterize complex fluids. Spatially resolved measurements in the velocity gradient direction are possible for studying shear-banding materials. Applications include investigations of colloidal dispersions, polymer solutions, and self-assembled structures.

Mesure microstructure du matériau sous flux utilisant 1-2 Avion Flow-Petit Angle Neutron Scattering

A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is ...

Recherche

Ingénierie

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

The durability of polymers and fiber-reinforced polymer composites in service is a critical aspect for their designs and condition-based maintenance. We present a novel low-cost laboratory testing platform for the investigation of the influence of concurrent mechanical and environmental loadings, and may help design more efficient yet safer composite structures.

Une plate-forme d&#39;essais pour une durabilité études de polymères renforcés de fibres et polymères Composites sous stimuli Concurrent Hygrothermo-mécanique

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs ...

Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too.

In this article, an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering is presented. Results on the emission of engineered nanomaterials, in the form of aerosols are presented. The specific experimental set-up is described in detail.

Protocole expérimental pour enquêter sur des particules Aérosolisation d&#39;un produit sous Abrasion et sous Weathering environnementale

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental ...

Design and Use of a Full Flow Sampling System (FFS) for the Quantification of Methane Emissions

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas industry faces continued scrutiny for methane emissions from across the supply chain, due to methane&#39;s relatively high global warming potential (25-84x that of carbon dioxide, according to the Energy Information Administration). Currently, a variety of techniques of varied uncertainties exists to measure or estimate methane emissions from components or facilities. Currently, only one commercial system is available for quantification of component level emissions and recent reports have highlighted its weaknesses.
In order to improve accuracy and increase measurement flexibility, we have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases based on transportation emissions measurement principles. The FFS is a modular system that consists of an explosive-proof blower(s), mass airflow sensor(s) (MAF), thermocouple, sample probe, constant volume sampling pump, laser based greenhouse gas sensor, data acquisition device, and analysis software. Dependent upon the blower and hose configuration employed, the current FFS is able to achieve a flow rate ranging from 40 to 1,500 standard cubic feet per minute (SCFM). Utilization of laser-based sensors mitigates interference from higher hydrocarbons (C2+). Co-measurement of water vapor allows for humidity correction. The system is portable, with multiple configurations for a variety of applications ranging from being carried by a person to being mounted in a hand drawn cart, on-road vehicle bed, or from the bed of utility terrain vehicles (UTVs). The FFS is able to quantify methane emission rates with a relative uncertainty of &#177; 4.4%. The FFS has proven, real world operation for the quantification of methane emissions occurring in conventional and remote facilities.

Design and Use of a Full Flow Sampling System FFS for the Quantification of Methane Emissions

We have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases from across the natural gas supply chain.

Conception et utilisation d&#39;un système d&#39;échantillonnage plein débit (FFS) pour la quantification des émissions de méthane

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas ...

A Robotic Platform to Study the Foreflipper of the California Sea Lion

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most of their thrust with their large foreflippers. This protocol describes a robotic platform designed to study the hydrodynamic performance of the swimming California sea lion (Zalophus californianus). The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;). The kinematics of the sea lion&#39;s propulsive stroke are extracted from video data of unmarked, non-research sea lions at the Smithsonian Zoological Park (SNZ). Those data form the basis of the actuation motion of the robotic flipper presented here. The geometry of the robotic flipper is based a on high-resolution laser scan of a foreflipper of an adult female sea lion, scaled to about 60% of the full-scale flipper. The articulated model has three joints, mimicking the elbow, wrist and knuckle joint of the sea lion foreflipper. The robotic platform matches dynamics properties&#8212;Reynolds number and tip speed&#8212;of the animal when accelerating from rest. The robotic flipper can be used to determine the performance (forces and torques) and resulting flowfields.

A robotic platform is described that will be used to study the hydrodynamic performance&#8212;forces and flowfields&#8212;of the swimming California sea lion. The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;).

Une plate-forme robotique pour étudier la Foreflipper de la mer Lion Californie

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

Collage de solvant pour la fabrication de PMMA et COP dispositifs microfluidiques

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes. The combination of the sapphire window from the micro-reactor with the cross-polarizer module of the microscope on the light path allows high-contrast imaging of isotropic and anisotropic media. While observations are carried out, the micro-reactor can be heated to the temperature range of cracking reactions (up to 450 &#176;C), can be subjected to H2 pressure relevant to hydroconversion reactions (up to 16 MPa), and can stir the sample by magnetic coupling. 
Observations are typically carried out by taking snapshots of the sample under cross-polarized light at regular time intervals. Image analyses may not only provide information on the temperature, pressure, and reactive conditions yielding phase separation, but may also give an estimate of the evolution of the chemical (absorption/reflection spectra) and physical (refractive index) properties of the sample before the onset of phase separation.

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

This article describes a setup and method for the in situ visualization of oil samples under a variety of temperature and pressure conditions that aim to emulate refining and upgrading processes. It is primarily used for studying isotropic and anisotropic media involved in the fouling behavior of petroleum feeds.

In Situ Visualisation du comportement des échantillons de pétrole Phase Sous raffinerie processus Conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

Méthodologie basée sur le Profiler de diffusion de lumière de balayage (SLPS) pour évaluer quantitativement la diffusion de lumière vers l&#39;avant et vers l&#39;arrière à partir de lentilles intraoculaires

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

A Novel Biaxial Testing Apparatus for the Determination of Forming Limit under Hot Stamping Conditions

The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional experimental approaches, such as out-of-plane and in-plane tests, are not applicable to the determination of forming limits when heating and rapid cooling processes are introduced prior to forming for tests conducted under hot stamping conditions. A novel in-plane biaxial testing system was designed and used for the determination of forming limits of sheet metals at various strain paths, temperatures, and strain rates after heating and cooling processes in a resistance heating uniaxial testing machine. The core part of the biaxial testing system is a biaxial apparatus, which transfers a uniaxial force provided by the uniaxial testing machine to a biaxial force. One type of cruciform specimen was designed and verified for the formability test of aluminum alloy 6082 using the proposed biaxial testing system. The digital image correlation (DIC) system with a high-speed camera was used for taking strain measurements of a specimen during a deformation. The aim of proposing this biaxial testing system is to enable the forming limits of an alloy to be determined at various temperatures and strain rates under hot stamping conditions.

This protocol proposes a novel biaxial testing system used on a resistance heating uniaxial tensile test machine in order to determine the forming limit diagram (FLD) of sheet metals under hot stamping conditions.

Un nouvel appareil d&#39;essai biaxiale pour la détermination de la limite de formage à chaud sous conditions Stamping

The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional ...

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the main trend in the advanced development of flow cytometry. Notably, adding high-resolution imaging capabilities allows for the complex morphological analysis of cellular/sub-cellular structures. This is not possible with standard flow cytometers. However, it is valuable for advancing our knowledge of cellular functions and can benefit life science research, clinical diagnostics, and environmental monitoring. Incorporating imaging capabilities into flow cytometry compromises the assay throughput, primarily due to the limitations on speed and sensitivity in the camera technologies. To overcome this speed or throughput challenge facing imaging flow cytometry while preserving the image quality, asymmetric-detection time-stretch optical microscopy (ATOM) has been demonstrated to enable high-contrast, single-cell imaging with sub-cellular resolution, at an imaging throughput as high as 100,000 cells/s. Based on the imaging concept of conventional time-stretch imaging, which relies on all-optical image encoding and retrieval through the use of ultrafast broadband laser pulses, ATOM further advances imaging performance by enhancing the image contrast of unlabeled/unstained cells. This is achieved by accessing the phase-gradient information of the cells, which is spectrally encoded into single-shot broadband pulses. Hence, ATOM is particularly advantageous in high-throughput measurements of single-cell morphology and texture &#8211; information indicative of cell types, states, and even functions. Ultimately, this could become a powerful imaging flow cytometry platform for the biophysical phenotyping of cells, complementing the current state-of-the-art biochemical-marker-based cellular assay. This work describes a protocol to establish the key modules of an ATOM system (from optical frontend to data processing and visualization backend), as well as the workflow of imaging flow cytometry based on ATOM, using human cells and micro-algae as the examples.

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy ATOM

This protocol describes the implementation of an asymmetric-detection time-stretch optical microscopy system for single-cell imaging in ultrafast microfluidic flow and its applications in imaging flow cytometry.

Cytométrie de flux d&#39;imagerie microfluidique par détection asymétrique Microscopie optique à temps-étirement (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the ...