Questo studio è stato sostenuto da NIH R00HL102154, e un American Society of Hematology premio studioso P Ji.

Gli esperimenti descritti in questo protocollo sono stati eseguiti in conformità con le linee guida e regolamenti stabiliti dalla Northwestern University Institutional Animal Care and Use Committee. 1 Preparazione del terreno di coltura <ol><li> Preparare la soluzione fibronectina. Aggiungere 1 ml di acqua per una fiala di fibronectina umana (1 mg). Lasciare soluzione nel cappuccio coltura tissutale per 30 minuti senza agitazione. Trasferire il liquido totale di 50 ml di PBS per fare una concentrazione finale di 20 mg / ml e mescolare delicatamente bene. Rendere la soluzione fibronectina fresco prima del rivestimento della piastra (vedi sotto). </li><li> Preparare 50 ml di mezzo privo di Epo (SCF medio). Unire gli ingredienti elencati nella Tabella 1. Il terreno può essere conservato a 4 ° C per 1 mese se fatta fresca. </li><li> Preparare 50 ml di terreno contenente Epo. Unire gli ingredienti elencati nella Tabella 2. Il terreno può essere conservato a 4 ° C per 1 mese se fatta fresca. </li></ol&gt; 2 fibronectina piastra ricoperta <ol><li> Aggiungere 1 ml di soluzione fibronectina a ciascun pozzetto di una piastra da 6 pozzetti (o 0,5 ml a ciascun pozzetto di una piastra ben 12). Lasciare la piastra nella cappa coltura tissutale per 1 ora. </li><li> Sciacquare pozzi con acqua sterile per due volte e asciugare la piastra. </li><li> Avvolgere la piastra e salvare in cella a 4 ° C. </li></ol> 3. Purificazione di fegato fetali eritroblasti NOTA: Utilizzare i fegati fetali da E13 a E15 cronometrati topi in gravidanza (C57BL / 6). Fegati E13.5 sono preferiti per massimizzare il rendimento di CFU-E progenitori. Per ottenere i topi in gravidanza cronometrati, da 6 a 8 settimane di età maschi e femmine di topo sono stati collocati in una gabbia (di solito un maschio con una o due femmine). Tappi vaginali femminili sono state controllate la mattina seguente per determinare se l&#39;accoppiamento ha avuto successo. Il primo giorno di gestazione è stato il giorno dopo che è stata trovata la spina. <ol><li> Preparazione delle cellule totali fetale epatiche <ol><li> Sacrifica il mouse da CO 2 inalazione e dislocazione cervicale. Spruzzare l&#39;addome con etanolo al 70% per la disinfezione. Aprire l&#39;addome con dissezione forbici per rimuovere l&#39;utero. Lavare l&#39;utero in 1x PBS. </li><li> Sezionare i feti in condizioni sterili utilizzando una cappa coltura tissutale e strumenti in autoclave e lavare in PBS 1x. </li><li> Sezionare i fegati fetali da feti. Tenere il corpo del feto con una pinza, tirare delicatamente il fegato fetale (di colore rosa) lontano dal corpo con un altro pinze. Pulire il fegato fetale con le pinze per rimuovere i tessuti fibrotici associati. Mettere tutti i fegati fetali in fresco 1x PBS contenente siero fetale bovino al 10%. </li><li> Meccanicamente interrompere fegati fetali pipettando su e giù. </li><li> Filtrare la sospensione cellulare attraverso un colino cella di 40 micron in una provetta da 50 ml. Agglomerare le cellule a 800 xg per 5 min. </li><li> Aspirare il surnatante e risospendere le cellule in 1 ml di PBS con 10% FBS (circa 8 E13.5 fegati fetaliper ml). </li></ol></li><li> Purificazione di TER119 eritroblasti negativi <ol><li> Bloccare le cellule con IgG di ratto (0,2 mg / ml) in ghiaccio per 15 min. </li><li> Senza lavaggio o centrifugazione, aggiungere anticorpo anti-TER119 biotinilato alla sospensione cellulare (1 mg / ml). Incubare per 15 min in ghiaccio. </li><li> Lavare in 1x PBS con 10% FBS (1,10) e centrifugare a 800 xg per 5 min. Risospendere le cellule in 1 ml di PBS con 10% FBS. </li><li> Aggiungere 75 microlitri streptavidina coniugata con particelle magnetiche e incubare per 10 minuti in ghiaccio. </li><li> Aggiungere il volume a 2,5 ml con PBS contenente 10% FBS. Trasferire la sospensione cellulare in un 5 ml in polipropilene tondo tubo inferiore. </li><li> Inserire il tubo in un apparato cellulare smistamento magnetico e incubare per 10 min. Cellule positive TER119 potranno allegare al lato del tubo. Gli eritroblasti negativi TER119 distaccato rimarranno in sospensione. </li><li> Versare la sospensione cellulare in un nuovo 5 ml in polipropilene tondo tubo inferiore. </li><li><html> Ripetere i punti 3.2.6 e 3.2.7 per rimuovere le cellule positive TER119 residuo. </li><li> Agglomerare le cellule a 800 xg per 5 min. Aspirare il sopranatante. Risospendere le cellule in 1 ml di PBS contenente 10% FBS e contare le cellule vive con Trypan Blue. </li></ol></li></ol> 4. trasduzione con virus codifica cDNA o shRNA <ol><li> Piastra le cellule del fegato fetali negativi TER119 purificata a 3-5 x 10 5 / bene in un fibronectina rivestito 12-pozzetti (regolare il numero di cellulare se si utilizza un piatto diverso). </li><li> Aggiungere polibrene ad una concentrazione finale di 10 mg / ml per facilitare trasduzione virale. Spin infettare le cellule con lentivirus o retrovirus, cDNA codifica o shRNA, a 800 xg per 1-1,5 ore a 37 ° C. </li></ol> 5. Cultura dei trasdotte TER119 mouse Negativo fetali Fegato eritroblasti <ol><li> Per provare le funzioni del gene nella fase iniziale dell&#39;eritropoiesi terminale (Figura 1 linee tratteggiate).&quot;&gt; </ol.><ol><li><ol. li=""> Coltivare le cellule trasdotte in Epo mezzo privo (SCF media) per 12 ore per consentire l&#39;espressione dei geni e la manutenzione dello stato progenitore trasdotte. </ol.></li><li> Centrifugare le cellule a 800 xg per 5 min. Aspirare il surnatante. Risospendere le cellule in 1 ml di Epo contenenti mezzo in ogni pozzetto di una piastra 12 pozzetti. </li><li> Dopo cultura per 24 o 48 ore, raccogliere le cellule per ulteriori analisi. </li></ol></li><li> Funzioni del gene Test nella fase tardiva dell&#39;eritropoiesi terminale (Figura 1 linee continue). <ol><li> Coltivare le cellule trasdotte immediatamente in terreno contenente Epo. </li><li> Dopo cultura per 24 o 48 ore, raccogliere le cellule per ulteriori analisi. </li></ol></li></ol> 6. colorazione delle cellule in coltura fetale fegato per analisi citofluorimetrica <ol><li> Lavare e risospendere le cellule in PBS 1x. Harvest 2 x 10 5 cellule in coltura per l&#39;analisi di citometria di flusso. </li><li> Covarele cellule con anticorpi coniugati fluoroforo per 20 minuti a temperatura ambiente al buio. Per testare la differenziazione, utilizzare APC coniugato anti-CD71 e PE coniugato anti-TER119. Per testare enucleazione, utilizzare Hoechst 33342 macchia in aggiunta agli altri anticorpi. </li><li> Lavare le cellule con PBS 1x. Risospendere le cellule in 0,5 ml di PBS contenente 1% FBS e ioduro di propidio (PI) (1 mg / ml) per colorare le cellule morte ed escluderli dall&#39;analisi. </li><li> Comportamento analisi dei flussi cytrometric. Analizzare colore macchiato e non colorati cellule di controllo singole primo per la regolazione e la compensazione del citometro a flusso. </li></ol>

<ol>
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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alpha4beta1+integrin+and+erythropoietin+mediate+temporally+distinct+steps+in+erythropoiesis:+integrins+in+red+cell+development.">Alpha4beta1 integrin and erythropoietin mediate temporally distinct steps in erythropoiesis: integrins in red cell development.</a> The Journal of cell biology. 177 (5), 871-880 (2007).</li><li>Koury, M. J., Bondurant, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maintenance+by+erythropoietin+of+viability+and+maturation+of+murine+erythroid+precursor+cells.">Maintenance by erythropoietin of viability and maturation of murine erythroid precursor cells.</a> Journal of cellular physiology. 137 (1), 65-74 (1988).</li><li>Ji, P., Yeh, V., Ramirez, T., Murata-Hori, M., Lodish, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histone+deacetylase+2+is+required+for+chromatin+condensation+and+subsequent+enucleation+of+cultured+mouse+fetal+erythroblasts.">Histone deacetylase 2 is required for chromatin condensation and subsequent enucleation of cultured mouse fetal erythroblasts.</a> Haematologica. 95 (12), 2013-2021 (2010).</li><li>Dumitriu, B., 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=Sox6+cell-autonomously+stimulates+erythroid+cell+survival,+proliferation,+and+terminal+maturation+and+is+thereby+an+important+enhancer+of+definitive+erythropoiesis+during+mouse+development.">Sox6 cell-autonomously stimulates erythroid cell survival, proliferation, and terminal maturation and is thereby an important enhancer of definitive erythropoiesis during mouse development.</a> Blood. 108 (4), 1198-1207 (2006).</li><li>Rector, K., Liu, Y., Van Zant, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comprehensive+hematopoietic+stem+cell+isolation+methods.">Comprehensive hematopoietic stem cell isolation methods.</a> Methods in molecular biology. 976, 1-15 (2013).</li><li>Rossi, L., Challen, G. A., Sirin, O., Lin, K. K., Goodell, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hematopoietic+stem+cell+characterization+and+isolation.">Hematopoietic stem cell characterization and isolation.</a> Methods in molecular biology. 750, 47-59 (2011).</li><li>Choi, H. S., Lee, E. M., Kim, H. O., Park, M. I., Baek, E. 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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+Ras+signaling+in+erythroid+differentiation+of+mouse+fetal+liver+cells:+functional+analysis+by+a+flow+cytometry-based+novel+culture+system.">Role of Ras signaling in erythroid differentiation of mouse fetal liver cells: functional analysis by a flow cytometry-based novel culture system.</a> Blood. 102 (12), 3938-3946 (2003).</li><li>Socolovsky, 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=Ineffective+erythropoiesis+in+Stat5a(-/-)5b(-/-)+mice+due+to+decreased+survival+of+early+erythroblasts.">Ineffective erythropoiesis in Stat5a(-/-)5b(-/-) mice due to decreased survival of early erythroblasts.</a> Blood. 98 (12), 3261-3273 (2001).</li><li>Ji, P., Jayapal, S. R., Lodish, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enucleation+of+cultured+mouse+fetal+erythroblasts+requires+Rac+GTPases+and+mDia2.">Enucleation of cultured mouse fetal erythroblasts requires Rac GTPases and mDia2.</a> Nature cell biology. 10 (3), 314-321 (2008).</li><li>Chida, D., Miura, O., Yoshimura, A., Miyajima, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+cytokine+signaling+molecules+in+erythroid+differentiation+of+mouse+fetal+liver+hematopoietic+cells:+functional+analysis+of+signaling+molecules+by+retrovirus-mediated+expression.">Role of cytokine signaling molecules in erythroid differentiation of mouse fetal liver hematopoietic cells: functional analysis of signaling molecules by retrovirus-mediated expression.</a> Blood. 93 (5), 1567-1578 (1999).</li><li>Patel, V. P., Lodish, H. 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Gli autori dichiarano di non avere interessi finanziari in competizione.

Qui vi presentiamo un sistema unico per analizzare cronologicamente topo fetale eritropoiesi terminale del fegato. Attraverso l&#39;applicazione di diverse condizioni di coltura, abbiamo sezionato con successo l&#39;eritropoiesi terminale in fase precoce e tardiva. Ciò è particolarmente importante per determinare i meccanismi di geni con funzioni multiple. Ad esempio, GTPasi Rac svolgono un ruolo importante in diverse fasi della eritropoiesi terminale. Inibizione della Rac GTPasi nella fase iniziale della differenziaz...

L&#39;eritropoiesi è il processo di differenziazione delle cellule staminali ematopoietiche multipotenti a maturare eritrociti. Questo processo graduale prevede la formazione di unità formanti impegnata a raffica eritroide (BFU-Es), le unità formanti colonia in rapida divisione eritroidi (CFU-Es), e morfologicamente riconoscibili eritroblasti 1,2. Eritropoiesi Terminal da cellule progenitrici CFU-E coinvolge sequenziale eritropoietina-dipendente e fasi indipendenti 2,3. Nella fase iniziale dell&#39;eritropoiesi terminale, eritropoietina (Epo) si lega al suo recettore sulla superficie cellulare e induce una serie di vie di segnalazione a valle che impediscono l&#39;apoptosi delle cellule e promuovono divisioni cellulari rapidi e l&#39;espressione genica 1,4. Nella fase tardiva dell&#39;eritropoiesi terminale, eritroblasti subiscono uscita cellula terminale del ciclo, cromatina e di nuclei di condensazione, e l&#39;estrusione dei nuclei altamente condensati 5. La nostra comprensione di terminaleeritropoiesi ha notevolmente migliorato negli ultimi decenni, che è in gran parte dovuto il successo nell&#39;uso di diversi in vitro e in modelli in vivo di topo 6-9. Tra questi modelli, la coltura in vitro di topo fetale eritroblasti fegato fornisce molti vantaggi tra cui la facilità di purificazione delle cellule, la proliferazione e la differenziazione veloce, e una mimica più vicino a eritropoiesi umana 10,11. In questo sistema, un gran numero di cellule progenitrici eritroidi da topo fegati fetali possono essere facilmente isolate dalla purificazione singolo passo di TER119 (un marcatore per le cellule eritroidi mature) eritroblasti negativi. Durante la cultura di due giorni degli eritroblasti, la differenziazione di queste cellule può essere monitorato da un citometria a flusso basato sulla superficie espressione del recettore della transferrina (CD71) e la TER119 dell&#39;antigene 12. Inoltre, l&#39;enucleazione dei eritroblasti differenziazione terminale può essere rilevata da un produttore di DNA (Hoechst 33342) 13. Inoltre, i progenitori purificati possono essere geneticamente modificati espressione esogena di cDNA o piccoli RNA hairpin (shRNAs) per i geni di interesse, che facilita gli studi meccanicistici delle funzioni di espressione genica su eritropoiesi 11,13,14. D&#39;altra parte, il tasso di crescita delle cellule veloce può essere una lama a doppio taglio poiché è difficile caratterizzare funzioni geniche nelle diverse fasi di eritropoiesi terminale. Nella maggior parte dei casi, è difficile stabilire se una specifica funzioni del gene nella fase iniziale dell&#39;eritropoiesi terminale fin dal momento in cui il cDNA o shRNAs espresso, le cellule già superato la fase iniziale. Per risolvere questo problema, abbiamo sviluppato un sistema unico di sezionare prime e ultime fasi dell&#39;eritropoiesi terminale. Per la fase iniziale di eritropoiesi terminale, geneticamente modificati TER119 eritroblasti negative sono state coltivate in terreno Epo-libero ma contenente fattore delle cellule staminali (SCF), IL-6 e FLT3ligando di mantenere il loro status progenitore e consentire i cDNA trasdotte o shRNA all&#39;espressione 13. Le cellule sono state modificate per Epo contenente medio dopo 12 ore per indurre la proliferazione e differenziazione cellulare. In questo modo, quando le cellule hanno cominciato a differenziarsi, i cDNA trasdotte o shRNAs erano già espressi. Per la fase tardiva dell&#39;eritropoiesi terminale, TER119 eritroblasti negative sono state coltivate in terreno contenente Epo subito dopo la trasduzione. Pertanto, si può analizzare le funzioni dei geni di interesse nella fase tardiva della eritropoiesi terminale. In sintesi, una vasta applicazione di questo sistema aiuterebbe funzioni geniche sezionare in diverse fasi della eritropoiesi terminale.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Iscove&#39;s Modified Dulbecco&#39;s MediumIMDM (IMDM)</td>
			<td>Gibco</td>
			<td>12440-053</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum (FBS)</td>
			<td>GEMINI Bio-product</td>
			<td>700-102P</td>
			<td></td>
		</tr>
		<tr>
			<td>b-mecaptoethanol</td>
			<td>Sigma</td>
			<td>M6250</td>
			<td>0.1 M in IMDM,&#160; 4&#8451;stock</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin solution</td>
			<td>Hyclone</td>
			<td>SV30010</td>
			<td>100 X</td>
		</tr>
		<tr>
			<td>L-Glutamine</td>
			<td>Hyclone</td>
			<td>SH30034.01</td>
			<td>200 mM</td>
		</tr>
		<tr>
			<td>Stem cell factor (SCF)</td>
			<td>STEMCELL TECH</td>
			<td>2630</td>
			<td>100 ng/ul, -20&#8451; stock</td>
		</tr>
		<tr>
			<td>Mouse FIT3 Ligand (Flt-3L)</td>
			<td>BD Biosciences&#160;</td>
			<td>14-8001-80</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse Recombinant Interleukin-6 (IL-6)&#160;</td>
			<td>GEMINI Bio-product</td>
			<td>300-327P</td>
			<td></td>
		</tr>
		<tr>
			<td>fibronectin</td>
			<td>BD Biosciences&#160;</td>
			<td>354008</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin (BSA)</td>
			<td>STEMCELL TECH</td>
			<td>9300</td>
			<td>10% stock in IMDM</td>
		</tr>
		<tr>
			<td>Insulin solution, human</td>
			<td>Sigma</td>
			<td>I9278</td>
			<td>4&#8451; stock</td>
		</tr>
		<tr>
			<td>holo-transferrin human</td>
			<td>Sigma</td>
			<td>T0665</td>
			<td>50 mg/ml in Water -20&#8451; stock</td>
		</tr>
		<tr>
			<td>Erythropoietin(Epo)</td>
			<td>PROCRIT</td>
			<td>NOC 59676-303-00</td>
			<td>3,000 U/ml stock</td>
		</tr>
		<tr>
			<td>Streptavidin particles Plus</td>
			<td>BD Pharmingen</td>
			<td>557812</td>
			<td></td>
		</tr>
		<tr>
			<td>EasySep Magnet</td>
			<td>STEMCELL TECH</td>
			<td>18000</td>
			<td></td>
		</tr>
		<tr>
			<td>Polypropylene Round-Bottom Tube, 5 ml</td>
			<td>FALCON</td>
			<td>352063</td>
			<td></td>
		</tr>
	</tbody>
</table>

mouse fetal liver culture system to dissect target gene functions at the early and late stages of terminal erythropoiesis

Eritropoiesi comporta un processo dinamico che inizia con unità formanti impegnata a raffica eritroide (BFU-Es), seguita da rapida divisione eritroide unità formanti colonia (CFU-E). Dopo CFU-Es, le cellule sono morfologicamente riconoscibili e generalmente chiamato eritroblasti terminali. Una delle sfide per lo studio dell&#39;eritropoiesi terminale è la mancanza di approcci sperimentali per analizzare le funzioni del gene in modo cronologico. In questo protocollo, si descrive una strategia unica per determinare le funzioni del gene nelle prime e ultime fasi dell&#39;eritropoiesi terminale. In questo sistema, il mouse TER119 fegato fetale (marker delle cellule eritroidi mature) eritroblasti negativi sono stati purificati e trasdotto con espressione esogena di cDNA o piccoli RNA hairpin (shRNAs) per i geni di interesse. Le cellule sono state poi coltivate in terreno contenente fattori di crescita diversi eritropoietina (Epo) per mantenere la loro fase progenitore per 12 ore, consentendo cDNA esogeni o shRNAsdi esprimere. Le cellule sono state modificate per Epo media dopo 12 ore di indurre il differenziamento e la proliferazione cellulare, mentre il materiale genetico esogeno erano già espressi. Questo protocollo facilita l&#39;analisi delle funzioni dei geni nella fase iniziale dell&#39;eritropoiesi terminale. Per studiare terminale eritropoiesi fase tardiva, le cellule sono state coltivate in Epo immediatamente medio dopo trasduzione. In questo modo, le cellule sono state già differenziate per la fase tardiva dell&#39;eritropoiesi terminale quando sono stati espressi i materiali genetici trasdotte. Si consiglia una applicazione generale di questa strategia che potrebbe aiutare a capire le funzioni del gene dettagliate in diverse fasi della eritropoiesi terminale.

La figura 1 illustra le strategie sperimentali. Il protocollo consiste di due condizioni indipendenti per il targeting le funzioni delle molecole di segnalazione nelle prime e ultime fasi della eritropoiesi terminale. TER119 eritroblasti fegato fetale negativi sono stati purificati da topo E13.5 feto. Analisi citofluorimetrica delle cellule eritroidi fegato fetale prima e dopo la purificazione dimostrato che la purificazione era efficiente (Figure 2A e 2B). Per la fase ...

Watch this Scientific Journal Video about Mouse Fetal Liver Culture System to Dissect Target Gene Functions at the Early and Late Stages of Terminal Erythropoiesis at JoVE.com

Mouse Fetal Liver Culture System to Dissect Target Gene Functions at the Early and Late Stages of Terminal Erythropoiesis

Vi presentiamo un mouse fetale sistema di coltura in vitro eritroblasto fegato che analizza le fasi precoce e tardiva dell&#39;eritropoiesi terminale. Questo sistema facilita l&#39;analisi funzionale di geni specifici in diversi stadi di sviluppo.

Mouse fetale Fegato Cultura di sistema per sezionare Funzioni gene bersaglio nelle fasi precoci e tardivi del Terminal eritropoiesi

Erythropoiesis involves a dynamic process that begins with committed erythroid burst forming units (BFU-Es) followed by rapidly dividing erythroid colony ...

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Cell Biology

Immunology and Infection

Unit 1

A Hierarchical Stem-Cell System: Blood Cell Formation

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14.8K Views.  Northwestern University.  Vi presentiamo un mouse fetale sistema di coltura in vitro eritroblasto fegato che analizza le fasi precoce e tardiva dell'eritropoiesi terminale. Questo sistema facilita l'analisi funzionale di geni specifici in diversi stadi di sviluppo. 

Video: Mouse Fetal Liver Culture System to Dissect Target Gene Functions at the Early and Late Stages of Terminal Erythropoiesis

Introducing Shear Stress in the Study of Bacterial Adhesion

During bacterial infections a sequence of interactions occur between the pathogen and its host. Bacterial adhesion to the host cell surface is often the initial and determining step of the pathogenesis. Although experimentally adhesion is mostly studied in static conditions adhesion actually takes place in the presence of flowing liquid. First encounters between bacteria and their host often occur at the mucosal level, mouth, lung, gut, eye, etc. where mucus flows along the surface of epithelial cells. Later in infection, pathogens occasionally access the blood circulation causing life-threatening illnesses such as septicemia, sepsis and meningitis. A defining feature of these infections is the ability of these pathogens to interact with endothelial cells in presence of circulating blood. The presence of flowing liquid, mucus or blood for instance, determines adhesion because it generates a mechanical force on the pathogen. To characterize the effect of flowing liquid one usually refers to the notion of shear stress, which is the tangential force exerted per unit area by a fluid moving near a stationary wall, expressed in dynes/cm2. Intensities of shear stress vary widely according to the different vessels type, size, organ, location etc. (0-100 dynes/cm2). Circulation in capillaries can reach very low shear stress values and even temporarily stop during periods ranging between a few seconds to several minutes 1. On the other end of the spectrum shear stress in arterioles can reach 100 dynes/cm2 2. The impact of shear stress on different biological processes has been clearly demonstrated as for instance during the interaction of leukocytes with the endothelium 3. To take into account this mechanical parameter in the process of bacterial adhesion we took advantage of an experimental procedure based on the use of a disposable flow chamber 4. Host cells are grown in the flow chamber and fluorescent bacteria are introduced in the flow controlled by a syringe pump. We initially focused our investigations on the bacterial pathogen Neisseria meningitidis, a Gram-negative bacterium responsible for septicemia and meningitis. The procedure described here allowed us to study the impact of shear stress on the ability of the bacteria to: adhere to cells 1, to proliferate on the cell surface 5and to detach to colonize new sites 6 (Figure 1). Complementary technical information can be found in reference 7. Shear stress values presented here were chosen based on our previous experience1 and to represent values found in the literature. The protocol should be applicable to a wide range of pathogens with specific adjustments depending on the objectives of the study.

During the infection process, a key step is the adhesion of pathogens with host cells. In most instances this adhesion step occurs in the presence of mechanical stress generated by flowing liquid. We describe a technique that introduces shear stress as an important parameter in the study of bacterial adhesion.

L&#39;introduzione di shear stress nello studio di adesione batterica

During bacterial infections a sequence of interactions occur between the pathogen and its host. Bacterial adhesion to the host cell surface is often the ...

Ricerca

Immunologia e infezioni

Using the BLT Humanized Mouse as a Stem Cell based Gene Therapy Tumor Model

Small animal models such as mice have been extensively used to study human disease and to develop new therapeutic interventions. Despite the wealth of information gained from these studies, the unique characteristics of mouse immunity as well as the species specificity of viral diseases such as human immunodeficiency virus (HIV) infection led to the development of humanized mouse models. The earlier models involved the use of C. B 17 scid/scid mice and the transplantation of human fetal thymus and fetal liver termed thy/liv (SCID-hu) 1, 2 or the adoptive transfer of human peripheral blood leukocytes (SCID-huPBL) 3. Both models were mainly utilized for the study of HIV infection.
One of the main limitations of both of these models was the lack of stable reconstitution of human immune cells in the periphery to make them a more physiologically relevant model to study HIV disease. To this end, the BLT humanized mouse model was developed. BLT stands for bone marrow/liver/thymus. In this model, 6 to 8 week old NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) immunocompromised mice receive the thy/liv implant as in the SCID-hu mouse model only to be followed by a second human hematopoietic stem cell transplant 4. The advantage of this system is the full reconstitution of the human immune system in the periphery. This model has been used to study HIV infection and latency 5-8.
We have generated a modified version of this model in which we use genetically modified human hematopoietic stem cells (hHSC) to construct the thy/liv implant followed by injection of transduced autologous hHSC 7, 9. This approach results in the generation of genetically modified lineages. More importantly, we adapted this system to examine the potential of generating functional cytotoxic T cells (CTL) expressing a melanoma specific T cell receptor. Using this model we were able to assess the functionality of our transgenic CTL utilizing live positron emission tomography (PET) imaging to determine tumor regression (9).
The goal of this protocol is to describe the process of generating these transgenic mice and assessing in vivo efficacy using live PET imaging. As a note, since we use human tissues and lentiviral vectors, our facilities conform to CDC NIH guidelines for Biosafety Level 2 (BSL2) with special precautions (BSL2+). In addition, the NSG mice are severely immunocompromised thus, their housing and maintenance must conform to the highest health standards (<a href="http://jaxmice.jax.org/research/immunology/005557-housing.html" target="_blank">http://jaxmice.jax.org/research/immunology/005557-housing.html</a>).

The generation and characterization of tumor specific T cells using humanized mice is described here. Human thymic tissue and genetically modified human hematopoietic stem cells are transplanted into immunocompromised mice. This results in the reconstitution of an engineered human immune system allowing for in vivo examination of anti-tumor immune responses.

Uso del mouse BLT umanizzato come cellule staminali basata su un Modello Tumore Terapia Genica

Small animal models such as mice have been extensively used to study human  disease and to develop new therapeutic interventions. Despite the wealth of  ...

Multi-target Parallel Processing Approach for Gene-to-structure Determination of the Influenza Polymerase PB2 Subunit

Pandemic outbreaks of highly virulent influenza strains can cause widespread morbidity and mortality in human populations worldwide. In the United States alone, an average of 41,400 deaths and 1.86 million hospitalizations are caused by influenza virus infection each year 1. Point mutations in the polymerase basic protein 2 subunit (PB2) have been linked to the adaptation of the viral infection in humans 2. Findings from such studies have revealed the biological significance of PB2 as a virulence factor, thus highlighting its potential as an antiviral drug target.
The structural genomics program put forth by the National Institute of Allergy and Infectious Disease (NIAID) provides funding to Emerald Bio and three other Pacific Northwest institutions that together make up the Seattle Structural Genomics Center for Infectious Disease (SSGCID). The SSGCID is dedicated to providing the scientific community with three-dimensional protein structures of NIAID category A-C pathogens. Making such structural information available to the scientific community serves to accelerate structure-based drug design.
Structure-based drug design plays an important role in drug development. Pursuing multiple targets in parallel greatly increases the chance of success for new lead discovery by targeting a pathway or an entire protein family. Emerald Bio has developed a high-throughput, multi-target parallel processing pipeline (MTPP) for gene-to-structure determination to support the consortium. Here we describe the protocols used to determine the structure of the PB2 subunit from four different influenza A strains.

Structure-based drug design plays an important role in drug development. Pursuing multiple targets in parallel greatly increases the chance of success for lead discovery. The following article highlights how the Seattle Structural Genomics Center for Infectious Disease utilizes a multi-target approach for gene-to-structure determination of the PB2 influenza A subunit.

Multi-target Parallel Processing Approccio per Gene-to-struttura Determinazione della polimerasi Influenza PB2 subunità

Pandemic outbreaks of highly virulent influenza strains can cause widespread morbidity and mortality in human populations worldwide. In the United States ...

Vaccinia Reporter Viruses for Quantifying Viral Function at All Stages of Gene Expression

Poxviruses are a family of double stranded DNA viruses that include active human pathogens such as monkeypox, molluscum contagiousum, and Contagalo virus. The family also includes the smallpox virus, Variola. Due to the complexity of poxvirus replication, many questions still remain regarding their gene expression strategy. In this article we describe the conceptualization and usage of recombinant vaccinia viruses that enable real-time measurement of single and multiple stages of viral gene expression in a high-throughput format. This is enabled through the use of spectrally distinct fluorescent proteins as reporters for each of three stages of viral replication. These viruses provide a high signal-to-noise ratio while retaining stage specific expression patterns, enabling plate-based assays and microscopic observations of virus propagation and replication. These tools have uses for antiviral discovery, studies of the virus-host interaction, and evolutionary biology.

We describe the usage of a fluorescent reporter vaccinia virus that enables real-time measurement of viral infectivity and gene expression through the stage-specific expression of spectrally distinct reporter fluorophores. We detail a plate-based method for accurately identifying the stage at which virus replication is affected in response to small molecule inhibition.

Vaccinia Reporter virus per quantificare Funzione virale in tutte le fasi di espressione genica

Poxviruses are a family of double stranded DNA viruses that include active human pathogens such as monkeypox, molluscum contagiousum, and Contagalo virus. ...

Isolation of Leukocytes from the Murine Tissues at the Maternal-Fetal Interface

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing fetus. This tolerance is initiated during coitus, established during fecundation and implantation, and maintained throughout pregnancy. Active cellular and molecular mediators of maternal-fetal tolerance are enriched at the site of contact between fetal and maternal tissues, known as the maternal-fetal interface, which includes the placenta and the uterine and decidual tissues. This interface is comprised of stromal cells and infiltrating leukocytes, and their abundance and phenotypic characteristics change over the course of pregnancy. Infiltrating leukocytes at the maternal-fetal interface include neutrophils, macrophages, dendritic cells, mast cells, T cells, B cells, NK cells, and NKT cells that together create the local micro-environment that sustains pregnancy. An imbalance among these cells or any inappropriate alteration in their phenotypes is considered a mechanism of disease in pregnancy. Therefore, the study of leukocytes that infiltrate the maternal-fetal interface is essential in order to elucidate the immune mechanisms that lead to pregnancy-related complications. Described herein is a protocol that uses a combination of gentle mechanical dissociation followed by a robust enzymatic disaggregation with a proteolytic and collagenolytic enzymatic cocktail to isolate the infiltrating leukocytes from the murine tissues at the maternal-fetal interface. This protocol allows for the isolation of high numbers of viable leukocytes (&#62;70%) with sufficiently conserved antigenic and functional properties. Isolated leukocytes can then be analyzed by several techniques, including immunophenotyping, cell sorting, imaging, immunoblotting, mRNA expression, cell culture, and in vitro functional assays such as mixed leukocyte reactions, proliferation, or cytotoxicity assays.

Described herein is a protocol to isolate and analyze the infiltrating leukocytes of tissues at the maternal-fetal interface (uterus, decidua, and placenta) of mice. This protocol maintains the integrity of most cell surface markers and yields enough viable cells for downstream applications including flow cytometry analysis.

L&#39;isolamento dei leucociti di tessuti murini all&#39;interfaccia materno-fetale

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing ...

Human Placental and Decidual Organ Cultures to Study Infections at the Maternal-fetal Interface

The placenta shows a large degree of interspecies anatomic variability. To best understand biology and pathophysiology of the human placenta, it is imperative to design experiments using human cells and tissues. An advantage of organ culture is maintenance of three-dimensional (3D) structural organization and extracellular matrix. The goal of the method described here is successful establishment of ex vivo human gestational tissue organ cultures and their healthy culture maintenance for 72-96 hr. The protocol details the immediate processing of research-consented, placental and decidual specimens fresh from the operating suite. These are abundant specimens that would otherwise be discarded. Detailed instructions on the sterile collection of these samples, including morphologic details on how to select appropriate tissues to establish 3D organ cultures, is provided. Placental villous and decidual tissues are microdissected into 2-3 mm3 pieces and placed separately on matrix-lined transwell filters and cultured for several days. Villous and decidual organ cultures are well suited for the study of human host-pathogen interaction. As compared to other model organisms, these human cultures are particularly advantageous to examine mechanism of infection for pathogens that demonstrate variable patterns of host specificity. As an example, we demonstrate infection of placental and decidual organ cultures with the clinically relevant, facultative intracellular bacterial pathogen Listeria monocytogenes.

A simple method to establish primary human placental (villous) and decidual organ cultures is described. Villous and decidual organ cultures are invaluable tools for studying pathogenesis at the human maternal-fetal interface. Infection with the facultative intracellular bacterium Listeria monocytogenes is demonstrated.

Culture placentare e deciduale organo umano allo Studio infezioni all&#39;interfaccia materno-fetale

The placenta shows a large degree of interspecies anatomic variability. To best understand biology and pathophysiology of the human placenta, it is ...

Flow Cytometry-based Assay for the Monitoring of NK Cell Functions

Natural killer (NK) cells are an important part of the human tumor immune surveillance system. NK cells are able to distinguish between healthy and virus-infected or malignantly transformed cells due to a set of germline encoded inhibitory and activating receptors. Upon virus or tumor cell recognition a variety of different NK cell functions are initiated including cytotoxicity against the target cell as well as cytokine and chemokine production leading to the activation of other immune cells. It has been demonstrated that accurate NK cell functions are crucial for the treatment outcome of different virus infections and malignant diseases. Here a simple and reliable method is described to analyze different NK cell functions using a flow cytometry-based assay. NK cell functions can be evaluated not only for the whole NK cell population, but also for different NK cell subsets. This technique enables scientists to easily study NK cell functions in healthy donors or patients in order to reveal their impact on different malignancies and to further discover new therapeutic strategies.

A simple and reliable method is described here to analyze a set of NK cell functions such as degranulation, cytokine and chemokine production within different NK cell subsets.

Citometria a flusso basato su test per il monitoraggio delle funzioni delle cellule NK

Natural killer (NK) cells are an important part of the human tumor immune surveillance system. NK cells are able to distinguish between healthy and ...

Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), that carry foreign genes such as a reporter or marker protein in their genomes. These recombinant viruses usually faithfully mimic the life cycle of the original virus in infected cells and exhibit the same host range dependence. The development of a recombinant virus enables the efficient screening of inhibitors and the identification of specific host factors. However, to date the construction of recombinant hepatitis B virus (HBV) has been difficult because of various experimental limitations. The main limitation is the compact genome size of HBV, and a fairly strict genome size that does not exceed 1.3 genome sizes, that must be packaged into virions. Thus, the size of a foreign gene to be inserted should be smaller than 0.4 kb if no deletion of the genome DNA is to be performed. Therefore, to overcome this size limitation, the deletion of some HBV DNA is required. Here, we report the construction of recombinant HBV encoding a reporter gene to monitor the early stage of the HBV replication cycle by replacing part of the HBV core-coding region with the reporter gene by deleting part of the HBV pol coding region. Detection of recombinant HBV infection, monitored by the reporter activity, was highly sensitive and less expensive than detection using the currently available conventional methods to evaluate HBV infection. This system will be useful for a number of applications including high-throughput screening for the identification of anti-HBV inhibitors, host factors and virus-susceptible cells.

Here we describe a newly developed hepatitis B virus (HBV) reporter system to monitor the early stages of the HBV life cycle. This simplified in vitro system will aid in the screening of anti-HBV agents using a high-throughput strategy.

Sviluppo di un virus System Reporter dell&#39;epatite B per monitorare la fasi iniziali del ciclo di replicazione

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), ...

Generation of Escape Variants of Neutralizing Influenza Virus Monoclonal Antibodies

Influenza viruses exhibit a remarkable ability to adapt and evade the host immune response. One way is through antigenic changes that occur on the surface glycoproteins of the virus. The generation of escape variants is a powerful method in elucidating how viruses escape immune detection and in identifying critical residues required for antibody binding. Here, we describe a protocol on how to generate influenza A virus escape variants by utilizing human or murine monoclonal antibodies (mAbs) directed against the viral hemagglutinin (HA). With the use of our technique, we previously characterized critical residues required for the binding of antibodies targeting either the head or stalk of the novel avian H7N9 HA. The protocol can be easily adapted for other virus systems. Analyses of escape variants are important for modeling antigenic drift, determining single nucleotide polymorphisms (SNPs) conferring resistance and virus fitness, and in the designing of vaccines and/or therapeutics.

We describe a method by which we identify critical residues required for the binding of human or murine monoclonal antibodies that target the viral hemagglutinin of influenza A viruses. The protocol can be adapted to other virus surface glycoproteins and their corresponding neutralizing antibodies.

Generazione di varianti di fuga di neutralizzare l'Influenza Virus anticorpi monoclonali

Influenza viruses exhibit a remarkable ability to adapt and evade the host immune response. One way is through antigenic changes that occur on the surface ...

A Method to Assess Fc-mediated Effector Functions Induced by Influenza Hemagglutinin Specific Antibodies

Antibodies play a crucial role in coupling the innate and adaptive immune responses against viral pathogens through their antigen binding domains and Fc-regions. Here, we describe how to measure the activation of Fc effector functions by monoclonal antibodies targeting the influenza virus hemagglutinin with the use of a genetically engineered Jurkat cell line expressing an activating type 1 Fc-Fc&#947;R. Using this method, the contribution of specific Fc-Fc&#947;R interactions conferred by immunoglobulins can be determined using an in vitro assay.

We describe a method to measure the activation of Fc-mediated effector functions by antibodies that target the influenza virus hemagglutinin. This assay can also be adapted to assess the ability of monoclonal antibodies or polyclonal sera targeting other viral surface glycoproteins to induce Fc-mediated immunity.

Un metodo per valutare le funzioni effettrici Fc-mediata indotte dagli anticorpi specifici di Hemagglutinin di riossidazione

Antibodies play a crucial role in coupling the innate and adaptive immune responses against viral pathogens through their antigen binding domains and ...