Tracy C. Grikscheit, Erik R. Barthel, e Frédéric G. Sala sono supportati dal California Institute for Regenerative Medicine (CIRM), i numeri di concedere RN2-00946-1 (TCG) e TG2-01168 (ERB, FGS). Allison L. Speer è una Società di Chirurgia dell&#39;Università Ethicon studioso. Yashuhiro Torashima è finanziato da un ospedale pediatrico Fellowship Los Angeles Saban Research Career Development Institute.

1. Organoid unità di preparazione <ol><li> Strumenti adeguati per la dissezione del mouse (forbici e pinze) devono essere sterilizzati in autoclave. </li><li> Umanamente eutanasia il mouse donatore secondo protocolli locali IACUC. Assicurarsi che l&#39;animale è morto prima di procedere. </li><li> Fare una incisione mediana per accedere alla cavità peritoneale. Lembi cutanei può essere riflessa come necessario per migliorare l&#39;esposizione. </li><li> Sventrare il piccolo intestino e dividerlo appena distalmente al legamento di Treitz. Separare il piccolo intestino dal suo mesentere con tagliente e dolce smussa. Identificare la giunzione ileocecale e dividere il piccolo intestino 5 millimetri prossimale a questo. </li><li> Con forbici, aprire l&#39;intestino longitudinalmente lungo il confine antimesenterico in una piastra di Petri con 10 ml 4 ° C, soluzione salina tamponata sterile Hanks &#39;(HBSS, Invitrogen, Carlsbad CA) / 1X antibiotico-antimicotico (Anti-Anti, Invitrogen) soluzione. Cancella materia fecale dall&#39;intestino aperto conagitazione poi trasferimento intestino aperto un tubo da centrifuga 15 ml con 10 ml di 4 ° C, sterili HBSS / 1X anti-anti. </li><li> Lavare l&#39;intestino aperto tre volte in 10 ml di 4 ° C, HBSS 1X sterile / anti-anti in una provetta. Ogni lavaggio può essere eseguito con lieve agitazione del tubo 15 ml per 30 sec. Dopo agitazione, il tessuto intestinale scende sul fondo della provetta. Eliminare materiale galleggiante, che è detriti mesenchimale. Rimuovere la soluzione di lavaggio accuratamente con una pipetta. </li><li> Tritare l&#39;intestino lavato in una piastra di Petri con 10 ml di 4 ° C, HBSS 1X sterile / anti-anti a meno di 1 millimetro pezzi quadrati utilizzando un paio di forbici. Raccogliere il materiale tritato con una pipetta automatica e metterla in una provetta. </li><li> Centrifugare la provetta a 500 rpm per 8 min. Eliminare il supernatante, che contiene grassi e mesenchima. </li><li> Digerire il tritato, materiale lavato con 10 ml di HBSS sterili / 1X anti-anti + 0,125 mg / ml dispasi (Invitrogen) e 800 unità / ml collagenasi di tipo 1 (Worthington, Lakewood NJ). Per preparare 40 ml della soluzione di digestione, pesare 5 mg di dispasi, 142 mg di collagenasi, e aggiungere HBSS sterili fino ad un volume di 40 ml. Preparare questa soluzione fresca ogni unità di tempo organoid sono preparati, e mantenere a 4 ° C fino al momento dell&#39;uso. Aggiungere la soluzione digestione direttamente al pellet dal passo 1,8. </li><li> Incubare la provetta contenente il macinato, materiale lavato con la soluzione di digestione a 37 ° C per 20 min. </li><li> Recuperare la provetta e in seguito a distruggere il tessuto digerito da triturazione con una pipetta 10 ml. Ripetere tra 20 fino a 50 volte un aspetto uniforme. </li><li> Centrifugare la provetta per 5 min a 800 rpm. Eliminare il supernatante, che contiene le cellule singole. </li><li> Arrestare la reazione di digestione con 10 ml di 4 ° C, sterile Eagle modificato da Dulbecco (DMEM, Invitrogen) più 10% v / v di calore-siero fetale bovino inattivato (HI-FBS, Invitrogen). Risospendere la pellet e agitare la provetta. </li><li> Centrifugare la provetta per 5 min a 800 rpm. Rimuovere il surnatante con cura con una pipetta automatica fino a quando le ultime gocce. Utilizzare una pipetta di plastica monouso per le ultime gocce per evitare di risospensione del pellet. </li></ol> 2. Caricamento di acido poliglicolico impalcatura <ol><li> Formare 2-mm, 5 mm di diametro scaffold cilindriche esterne di acido poliglicolico non tessuto (2 mm di spessore, 60 mg cm-3 densità apparente, la porosità&gt; 95%, Fibre Concordia, RI Coventry) come descritto nel rif. 4. </li><li> Tagliare il distale 2 mm di una usa e getta 1000 pipetta microlitro punta con le forbici preparati con etanolo al 70% in acqua distillata. </li><li> Posizionare il patibolo in un 4-pozzetti cultura. Caricare le unità organoid sull&#39;impalcatura con la pipetta 1000 microlitri, prima nel lume e quindi sulla superficie esterna. Utilizzare una pinza per garantire rivestimento del lume. Non disturbare o rompere la forma cilindrica del polimero. </li&gt; </ol> 3. L&#39;impianto in mouse Host <ol><li> Utilizzare un mouse singenici host lo stesso sfondo del donatore, se disponibile. In caso contrario, impiegano un diabetico non obesi immunocompromessi / immunodeficienza combinata grave o NOD / SCID animale (Jackson Laboratories, Sacramento CA). </li><li> Indurre l&#39;anestesia generale con isoflurano. Shave, preparazione ed attaccare l&#39;addome del mouse. </li><li> Eseguire un&#39;incisione 5 millimetri linea mediana per guadagnare l&#39;accesso alla cavità peritoneale. Identificare e sviscerare con attenzione l&#39;omento maggiore. Posizionare il polimero caricato sulla omento e avvolgerlo con il tessuto. Non strappare l&#39;omento. </li><li> Fissare il polimero all&#39;omento con una sutura 5-0 monocryl. Delicatamente sostituire il omento con il polimero avvolto nella sua posizione anatomica. </li><li> Chiudere l&#39;incisione addominale a strati con 4-0 punti di sutura Vicryl. Eseguire la chiusura dei muscoli e fare attenzione a non danneggiare i visceri addominali sotto l&#39;incisione. Utilizzare punti staccati per la pelle. </li><li> Somministrare analgesia postoperatoria con 2 mg / kg di ketoprofene (Ketofen, Fort Dodge Animal Health) in acqua sterile come un pomfo sottocutanea adiacente alla incisione. Gli animali devono essere valutati tutti i giorni e se l&#39;animale sta dimostrando segni di dolore o disagio, una dose supplementare di ketoprofene può essere somministrato il giorno post operatorio 2. Il terzo giorno post-operatorio, l&#39;animale deve essere totalmente recuperato senza evidenza di dolore o disagio. Se il dolore o angoscia continua il giorno post operatorio 3, questo è considerato anormale e dovrebbe essere affrontata in conformità con i protocolli di cura IACUC e animale degli impianti. </li><li> Lasciare il mouse per recuperare e il tessuto-ingegnerizzato intestino a crescere per quattro settimane. Dare l&#39;annuncio accesso animale libitum nei roditori chow (Lab Dieta 5001, PMI nutrizione, St. Louis MO) e acqua con Septra 200 mg / 40 mg per 5 ml (Hi-Tech Pharmacal, Amityville NY) alla diluizione 1:100. </li></ol> 4. Raccolto <ol><li> HumaNely eutanasia l&#39;animale ospite quattro settimane dopo l&#39;impianto. </li><li> Riaprire l&#39;incisione originale e riflettere la pelle cranialmente per facilitare l&#39;accesso alla cavità peritoneale. </li><li> Aprite il livello muscolare e di identificare il tessuto ingegnerizzato costrutto come un globo di tessuto. </li><li> Abbattere adesioni al costrutto da intra-addominale con visceri dissezione netta. </li><li> Fissare il costrutto in formalina per paraffina dopo il montaggio, oppure utilizzare il tessuto fresco per saggi biochimici come real-time PCR o isolamento delle proteine. </li></ol>

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	<li>Grikscheit, T. C., Siddique, A., Ochoa, E. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue-engineered+small+intestine+improves+recovery+after+massive+small+bowel+resection.">Tissue-engineered small intestine improves recovery after massive small bowel resection.</a> Ann. Surg. 240, 748-754 (2004).</li><li>Wales, P. W., Christison-Lagay, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short+bowel+syndrome:+epidemiology+and+etiology.">Short bowel syndrome: epidemiology and etiology.</a> Sem. Ped. Surg. 19, 3-9 (2010).</li><li>Evans, G. S., Flint, N., Somers, A. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+a+method+for+the+preparation+of+rat+intestinal+epithelial+cell+primary+cultures.">The development of a method for the preparation of rat intestinal epithelial cell primary cultures.</a> J. Cell Sci. 101, 219-231 (1992).</li><li>Sala, F. G., Matthews, J. A., Speer, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multicellular+approach+forms+a+significant+amount+of+tissue-engineered+small+intestine+in+the+mouse.">A multicellular approach forms a significant amount of tissue-engineered small intestine in the mouse.</a> Tiss. Eng. Part A. 17, 1841-1850 (2011).</li><li>Speer, A. L., Sala, F. G., Matthews, J. A., Grikscheit, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+tissue-engineered+stomach+demonstrates+epithelial+differentiation.">Murine tissue-engineered stomach demonstrates epithelial differentiation.</a> J. Surg. Res. 171, 6-14 (2011).</li><li>Haxhija, E. Q., Yang, H., Spencer, A. U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intestinal+epithelial+cell+proliferation+is+dependent+on+the+site+of+massive+small+bowel+resection.">Intestinal epithelial cell proliferation is dependent on the site of massive small bowel resection.</a> Pediatr. Surg. Int. 23, 379-390 (2007).</li><li>Zhao, L., Cheng, Z., Dhall, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+corrective+pullthrough+surgery+in+a+mouse+model+of+Hirschsprung's+disease.">A novel corrective pullthrough surgery in a mouse model of Hirschsprung's disease.</a> J. Pediatr. Surg. 44, 759-766 (2009).</li><li>Petrosyan, M., Guner, Y. S., Williams, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+concepts+regarding+the+pathogenesis+of+necrotizing+enterocolitis.">Current concepts regarding the pathogenesis of necrotizing enterocolitis.</a> Ped. Surg. Int. 25, 309-318 (2009).</li><li>Shew, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+concerns+in+malrotation+and+midgut+volvulus.">Surgical concerns in malrotation and midgut volvulus.</a> Ped. Radiol. 39, S167-S171 (2009).</li><li>Sampietro, G. M., Corsi, F., Maconi, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prospective+study+of+long-term+results+and+prognostic+factors+after+conservative+surgery+for+small+bowel+Crohn's+disease.">Prospective study of long-term results and prognostic factors after conservative surgery for small bowel Crohn's disease.</a> Clin. Gastroenterol. Hepatol. 7, 183-191 (2009).</li><li>Klempnauer, J., Grothues, F., Bektas, H., Pichlmayr, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+results+after+surgery+for+acute+mesenteric+ischemia.">Long-term results after surgery for acute mesenteric ischemia.</a> Surgery. , 121-239 (1997).</li><li>Fitzgibbons, S. C., Jones, B. A., Hull, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+between+biopsy-proven+parenteral+nutrition-associated+liver+fibrosis+and+biochemical+cholestasis+in+children+with+short+bowel+syndrome.">Relationship between biopsy-proven parenteral nutrition-associated liver fibrosis and biochemical cholestasis in children with short bowel syndrome.</a> J. Ped. Surg. 45, 95-99 (2010).</li><li>Spencer, A. U., Kovacevich, D., McKinney-Barnett, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pediatric+short+bowel+syndrome:+the+cost+of+comprehensive+care.">Pediatric short bowel syndrome: the cost of comprehensive care.</a> Am. J. Clin. Nutr. 88, 1552-1559 (2008).</li><li>Kato, T., Tzakis, A. G., Selvaggi, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intestinal+and+multivisceral+transplantation+in+children.">Intestinal and multivisceral transplantation in children.</a> Ann. Surg. 243, 756-766 (2006).</li><li>Reyes, J., Bueno, J., Kocoshis, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+status+of+intestinal+transplantation+in+children.">Current status of intestinal transplantation in children.</a> J. Ped. Surg. 33, 243-254 (1998).</li></ol>

Nessun conflitto di interessi dichiarati.

Vi presentiamo un protocollo per la produzione di tessuti ingegnerizzati intestino nel topo utilizzando un unità-on-scaffold approccio organoid. Le fasi più critiche sono quelle della preparazione organoid unità. Bisogna fare attenzione a pulire in modo adeguato e meccanicamente elaborare il tessuto, ma la stessa cura deve essere presa per non overdigest o overtriturate le unità organoid dopo la digestione viene eseguita (passo 1.11). Se questo è fatto, le unità organoid può essere ridotto a singole cellule, che ...

<table border="1"><tbody><tr><td> Nome del reagente </td><td> Azienda </td><td> Numero di catalogo </td><td> Commenti (opzionale) </td></tr><tr><td> HBSS </td><td> Gibco </td><td> 114170-112 </td><td></td></tr><tr><td> Antibiotico-antimicotica 100X </td><td> Invitrogen </td><td> 15240-062 </td><td></td></tr><tr><td> Dispasi </td><td> Gibco </td><td> 17105-041 </td><td></td></tr><tr><td> Collagenasi tipo 1 </td><td> Worthington </td><td> LS004194 </td><td></td></tr><tr><td> DMEM glucosio Alta 1X </td><td> Gibco </td><td> 11995-065 </td><td></td></tr><tr><td> Di calore FBS inattivato </td><td> Invitrogen </td><td> 16140-071 </td><td></td></tr><tr><td> Biofelt 100% PGA </td><td> Concordia Medical </td><td> FELT01-1005 </td><td> Per la preparazione del polimero, come in rif.4 </td></tr><tr><td> Poli-L-lattico </td><td> Durect </td><td> B6002-1 </td><td> Per la preparazione del polimero, come in rif. 4 </td></tr><tr><td> Collagene di tipo I, coda di topo </td><td> Sigma-Aldrich </td><td> C3867-1VL </td><td> Per la preparazione del polimero, come in rif. 4 </td></tr><tr><td> Ketoprofene 100 mg / ml </td><td> Fort Dodge Animal Health </td><td> 71-cheto-100-50 </td><td></td></tr><tr><td> LabDiet 5001 roditore chow </td><td> LabDiet </td><td> 5001 </td><td></td></tr><tr><td> Septra 200 mg / 40 mg per 5 ml, USP </td><td> Hi-Tech Pharmacal </td><td> 50383-824-16 </td><td></td></tr><tr><td> Isoflurano, USP </td><td> Phoenix Pharmaceuticals </td><td> 57319-507-06 </td><td></td></tr></tbody></table>

tissue engineering of the intestine in a murine model

Dell&#39;ingegneria tissutale piccolo intestino (TESI) è stato utilizzato con successo per salvare i ratti Lewis dopo massiccia resezione dell&#39;intestino tenue, con conseguente ritorno al peso pre-operatorie entro 40 giorni. 1 negli esseri umani, massiccia resezione del piccolo intestino può causare sindrome da intestino corto, un malassorbimento funzionale stato che conferisce una significativa morbidità, mortalità e costi sanitari tra cui la dipendenza nutrizione parenterale, insufficienza epatica e cirrosi, e la necessità di trapianti di organi multiviscerale. 2 In questo lavoro si descrivono e documentano il nostro protocollo per la creazione di tessuti ingegnerizzati intestino in un modello murino con una unità multicellulare organoid-on-scaffold approccio. Unità Organoid sono aggregati multicellulari derivanti dall&#39;intestino che contengono elementi sia delle mucose e mesenchimali, 3 il rapporto tra che conserva l&#39;intestinale nicchia delle cellule staminali. 4 Nella ricerca in corso e future, la transizione della nostra tecnica nelladel mouse consentirà di indagine dei processi che intervengono durante la formazione TESI utilizzando gli strumenti disponibili transgeniche in questa specie. 5 La disponibilità di ceppi di topi immunocompromessi inoltre ci permette di applicare la tecnica di tessuto intestinale umano e ottimizzare la formazione di TESI umana come xenotrapianto del mouse prima della sua transizione verso gli esseri umani. Il nostro metodo utilizza le buone prassi di fabbricazione (GMP) reagenti e materiali che sono già stati approvati per l&#39;uso in pazienti umani, e offre quindi un vantaggio significativo rispetto agli approcci che si basano su tessuti animali decellularizzato. L&#39;obiettivo finale di questo metodo è la sua traduzione per gli esseri umani come una strategia di medicina rigenerativa terapeutico per la sindrome dell&#39;intestino corto.

La figura 1 mostra uno schema generale per il protocollo qui documentato. Il risultato finale di questo protocollo è una struttura sferica del globo o tissutale intestino murino con un lume, mucosa, sottomucosa, muscolare e circostante. Figura 2A mostra un globo tipico rispetto ad un polimero di partenza patibolo. Figura 2B mostra lo stesso costrutto bruscamente bivalved di rivelare le sue lumen. Figura 3 illustra un ematossilina / eosina-stained paraf...

Watch this Scientific Journal Video about Tissue Engineering of the Intestine in a Murine Model at JoVE.com

Tissue Engineering of the Intestine in a Murine Model

Questo articolo e il video di accompagnamento presentare il nostro protocollo per la generazione di tessuto ingegnerizzato intestino nel topo, utilizzando un organoid unità-on-scaffold approccio.

L&#39;ingegneria dei tessuti del colon in un modello murino

Tissue-engineered small intestine (TESI) has successfully been used to rescue Lewis rats after massive small bowel resection, resulting in return to ...

tissue-engineering-of-the-intestine-in-a-murine-model

Research

JoVE Journal

Bioengineering

14.8K Views.  Keck School of Medicine of the University of Southern California. Questo articolo e il video di accompagnamento presentare il nostro protocollo per la generazione di tessuto ingegnerizzato intestino nel topo, utilizzando un organoid unità-on-scaffold approccio.

Video: Tissue Engineering of the Intestine in a Murine Model

Encapsulation of Cardiomyocytes in a Fibrin Hydrogel for Cardiac Tissue Engineering

Culturing cells in a three dimensional hydrogel environment is an important technique for developing constructs for tissue engineering as well as studying cellular responses under various culture conditions in vitro. The three dimensional environment more closely mimics what the cells observe in vivo due to the application of mechanical and chemical stimuli in all dimensions 1. Three-dimensional hydrogels can either be made from synthetic polymers such as PEG-DA 2 and PLGA 3 or a number of naturally occurring proteins such as collagen 4, hyaluronic acid 5 or fibrin 6,7. Hydrogels created from fibrin, a naturally occurring blood clotting protein, can polymerize to form a mesh that is part of the body's natural wound healing processes 8. Fibrin is cell-degradable and potentially autologous 9, making it an ideal temporary scaffold for tissue engineering.
Here we describe in detail the isolation of neonatal cardiomyocytes from three day old rat pups and the preparation of the cells for encapsulation in fibrin hydrogel constructs for tissue engineering. Neonatal myocytes are a common cell source used for in vitro studies in cardiac tissue formation and engineering 4. Fibrin gel is created by mixing fibrinogen with the enzyme thrombin. Thrombin cleaves fibrinopeptides FpA and FpB from fibrinogen, revealing binding sites that interact with other monomers 10. These interactions cause the monomers to self-assemble into fibers that form the hydrogel mesh. Because the timing of this enzymatic reaction can be adjusted by altering the ratio of thrombin to fibrinogen, or the ratio of calcium to thrombin, one can injection mold constructs with a number of different geometries 11,12. Further we can generate alignment of the resulting tissue by how we constrain the gel during culture 13.
After culturing the engineered cardiac tissue constructs for two weeks under static conditions, the cardiac cells have begun to remodel the construct and can generate a contraction force under electrical pacing conditions 6. As part of this protocol, we also describe methods for analyzing the tissue engineered myocardium after the culture period including functional analysis of the active force generated by the cardiac muscle construct upon electrical stimulation, as well as methods for determining final cell viability (Live-Dead assay) and immunohistological staining to examine the expression and morphology of typical proteins important for contraction (Myosin Heavy Chain or MHC) and cellular coupling (Connexin 43 or Cx43) between myocytes.

We describe the isolation of neonatal cardiomyocytes and the preparation of the cells for encapsulation in fibrin hydrogel constructs for tissue engineering. We describe methods for analyzing the tissue engineered myocardium after the culture period including active force generated upon electrical stimulation and cell viability and immunohistological staining.

Incapsulamento di cardiomiociti in un idrogel di fibrina per l&#39;ingegneria tissutale cardiaca

Culturing cells in a three dimensional hydrogel environment is an important technique for developing constructs for tissue engineering as well as studying ...

Ricerca

Bioingegneria

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.

Elaborazione Postproduzione di fibre elettrofilate per l&#39;ingegneria tissutale

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

Engineering Skeletal Muscle Tissues from Murine Myoblast Progenitor Cells and Application of Electrical Stimulation

Engineered muscle tissues can be used for several different purposes, which include the production of tissues for use as a disease model in vitro, e.g. to study pressure ulcers, for regenerative medicine and as a meat alternative 1. The first reported 3D muscle constructs have been made many years ago and pioneers in the field are Vandenburgh and colleagues 2,3. Advances made in muscle tissue engineering are not only the result from the vast gain in knowledge of biochemical factors, stem cells and progenitor cells, but are in particular based on insights gained by researchers that physical factors play essential roles in the control of cell behavior and tissue development. State-of-the-art engineered muscle constructs currently consist of cell-populated hydrogel constructs. In our lab these generally consist of murine myoblast progenitor cells, isolated from murine hind limb muscles or a murine myoblast cell line C2C12, mixed with a mixture of collagen/Matrigel and plated between two anchoring points, mimicking the muscle ligaments. Other cells may be considered as well, e.g. alternative cell lines such as L6 rat myoblasts 4, neonatal muscle derived progenitor cells 5, cells derived from adult muscle tissues from other species such as human 6 or even induced pluripotent stem cells (iPS cells) 7. Cell contractility causes alignment of the cells along the long axis of the construct 8,9 and differentiation of the muscle progenitor cells after approximately one week of culture. Moreover, the application of electrical stimulation can enhance the process of differentiation to some extent 8. Because of its limited size (8 x 2 x 0.5 mm) the complete tissue can be analyzed using confocal microscopy to monitor e.g. viability, differentiation and cell alignment. Depending on the specific application the requirements for the engineered muscle tissue will vary; e.g. use for regenerative medicine requires the up scaling of tissue size and vascularization, while to serve as a meat alternative translation to other species is necessary.

Engineered muscle tissue has great potential in regenerative medicine, as disease model and also as an alternative source for meat. Here we describe the engineering of a muscle construct, in this case from mouse myoblast progenitor cells, and the stimulation by electrical pulses.

Ingegneria tessuti muscolo scheletrico di cellule murine progenitrici mioblasti e di applicazione di stimolazione elettrica

Engineered muscle tissues can be used for several different purposes, which include the production of tissues for use as a disease model in vitro, e.g. to ...

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.

Progettazione di un biassiale Carico meccanico bioreattore per l&#39;ingegneria tissutale

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.

Ingegneria dei tessuti di un Umano 3D<em&gt; In vitro</em&gt; Sistema Tumore test

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

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

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

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

Generazione di una tridimensionale a tutto spessore della pelle Equivalent e Automated Ferimento

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

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.

Ingegneria 3D Cellularized collagene Gel per Vascolare Rigenerazione Tissutale

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

Tissue Engineering by Intrinsic Vascularization in an In Vivo Tissue Engineering Chamber

In reconstructive surgery, there is a clinical need for an alternative to the current methods of autologous reconstruction which are complex, costly and trade one defect for another. Tissue engineering holds the promise to address this increasing demand. However, most tissue engineering strategies fail to generate stable and functional tissue substitutes because of poor vascularization. This paper focuses on an in vivo tissue engineering chamber model of intrinsic vascularization where a perfused artery and a vein either as an arteriovenous loop or a flow-through pedicle configuration is directed inside a protected hollow chamber. In this chamber-based system angiogenic sprouting occurs from the arteriovenous vessels and this system attracts ischemic and inflammatory driven endogenous cell migration which gradually fills the chamber space with fibro-vascular tissue. Exogenous cell/matrix implantation at the time of chamber construction enhances cell survival and determines specificity of the engineered tissues which develop. Our studies have shown that this chamber model can successfully generate different tissues such as fat, cardiac muscle, liver and others. However, modifications and refinements are required to ensure target tissue formation is consistent and reproducible. This article describes a standardized protocol for the fabrication of two different vascularized tissue engineering chamber models in vivo.

Tissue Engineering by Intrinsic Vascularization in an In Vivo Tissue Engineering Chamber

This is a guideline for constructing in vivo vascularized tissue using a microsurgical arteriovenous loop or a flow-through pedicle configuration inside a tissue engineering chamber. The vascularized tissues generated can be employed for organ regeneration and replacement of tissue defects, as well as for drug testing and disease modeling.

Ingegneria dei tessuti da parte intrinseca Vascolarizzazione in un<em&gt; In Vivo</em&gt; Camera ingegneria dei tessuti

In reconstructive surgery, there is a clinical need for an alternative to the current methods of autologous reconstruction which are complex, costly and ...

The Arteriovenous (AV) Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering

A functional blood vessel network is a prerequisite for the survival and growth of almost all tissues and organs in the human body. Moreover, in pathological situations such as cancer, vascularization plays a leading role in disease progression. Consequently, there is a strong need for a standardized and well-characterized in vivo model in order to elucidate the mechanisms of neovascularization and develop different vascularization approaches for tissue engineering and regenerative medicine.
We describe a microsurgical approach for a small animal model for induction of a vascular axis consisting of a vein and artery that are anastomosed to an arteriovenous (AV) loop. The AV loop is transferred to an enclosed implantation chamber to create an isolated microenvironment in vivo, which is connected to the living organism only by means of the vascular axis. Using 3D imaging (MRI, micro-CT) and immunohistology, the growing vasculature can be visualized over time. By implanting different cells, growth factors and matrices, their function in blood vessel network formation can be analyzed without any disturbing influences from the surroundings in a well controllable environment. 
In addition to angiogenesis and antiangiogenesis studies, the AV loop model is also perfectly suited for engineering vascularized tissues. After a certain prevascularization time, the generated tissues can be transplanted into the defect site and microsurgically connected to the local vessels, thereby ensuring immediate blood supply and integration of the engineered tissue. By varying the matrices, cells, growth factors and chamber architecture, it is possible to generate various tissues, which can then be tailored to the individual patient's needs.

The Arteriovenous AV Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering

We describe a microsurgical approach for the generation of an arteriovenous (AV) loop as a model for analyzing vascularization in vivo in an isolated and well-characterized environment. This model is not only useful for the investigation of angiogenesis, but is also optimally suited for engineering axially vascularized and transplantable tissues.

Il arterovenosa (AV) loop in un modello di Piccoli Animali per studiare Angiogenesi e ingegneria dei tessuti vascolarizzati

A functional blood vessel network is a prerequisite for the survival and growth of almost all tissues and organs in the human body. Moreover, in ...

Treatment of Ligament Constructs with Exercise-conditioned Serum: A Translational Tissue Engineering Model

In vitro experiments are essential to understand biological mechanisms; however, the gap between monolayer tissue culture and human physiology is large, and translation of findings is often poor. Thus, there is ample opportunity for alternative experimental approaches. Here we present an approach in which human cells are isolated from human anterior cruciate ligament tissue remnants, expanded in culture, and used to form engineered ligaments. Exercise alters the biochemical milieu in the blood such that the function of many tissues, organs and bodily processes are improved. In this experiment, ligament construct culture media was supplemented with experimental human serum that has been &#39;conditioned&#39; by exercise. Thus the intervention is more biologically relevant since an experimental tissue is exposed to the full endogenous biochemical milieu, including binding proteins and adjunct compounds that may be altered in tandem with the activity of an unknown agent of interest. After treatment, engineered ligaments can be analyzed for mechanical function, collagen content, morphology, and cellular biochemistry. Overall, there are four major advantages versus traditional monolayer culture and animal models, of the physiological model of ligament tissue that is presented here. First, ligament constructs are three-dimensional, allowing for mechanical properties (i.e., function) such as ultimate tensile stress, maximal tensile load, and modulus, to be quantified. Second, the enthesis, the interface between boney and sinew elements, can be examined in detail and within functional context. Third, preparing media with post-exercise serum allows for the effects of the exercise-induced biochemical milieu, which is responsible for the wide range of health benefits of exercise, to be investigated in an unbiased manner. Finally, this experimental model advances scientific research in a humane and ethical manner by replacing the use of animals, a core mandate of the National Institutes of Health, the Center for Disease Control, and the Food and Drug Administration.

We present a model of ligament tissue in which three-dimensional constructs are treated with the human exercise-conditioned serum and analyzed for collagen content, function, and cellular biochemistry.

Trattamento delle strutture ligamentali con serum esercitato-condizionato: un modello di ingegneria tessuto transazionale

In vitro experiments are essential to understand biological mechanisms; however, the gap between monolayer tissue culture and human physiology is large, ...