Name: mouse fetal liver culture system to dissect target gene functions at the early and late stages of terminal erythropoiesis
Uploaded: 2014-09-09T15:00:00.000+00:00
Duration: 6 min 40 s
Description: 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

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>

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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><tbody><tr><td>Iscove&#039;s Modified Dulbecco&#039;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>Penicillin-Streptomycin solution</td><td>Hyclone</td><td>SV30010</td><td>100x</td></tr><tr><td>L-Glutamine</td><td>Hyclone</td><td>SH30034.01</td><td>200 mM</td></tr><tr><td>Mouse FIT3 Ligand (Flt-3L)</td><td>BD Biosciences&amp;nbsp;</td><td>14-8001-80</td><td></td></tr><tr><td>Mouse Recombinant Interleukin-6 (IL-6)&amp;nbsp;</td><td>GEMINI Bio-product</td><td>300-327P</td><td></td></tr><tr><td>Fibronectin</td><td>BD Biosciences&amp;nbsp;</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>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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A Hierarchical Stem-Cell System: Blood Cell Formation

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14.9K 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

Isolation of Murine Embryonic Hemogenic Endothelial Cells

The specification of hemogenic endothelial cells from embryonic vascular endothelium occurs during brief developmental periods within distinct tissues, and is necessary for the emergence of definitive HSPC from the murine extra embryonic yolk sac, placenta, umbilical vessels, and the embryonic aorta-gonad-mesonephros (AGM) region. The transient nature and small size of this cell population renders its reproducible isolation for careful quantification and experimental applications technically difficult. We have established a fluorescence-activated cell sorting (FACS)-based protocol for simultaneous isolation of hemogenic endothelial cells and HSPC during their peak generation times in the yolk sac and AGM. We demonstrate methods for dissection of yolk sac and AGM tissues from mouse embryos, and we present optimized tissue digestion and antibody conjugation conditions for maximal cell survival prior to identification and retrieval via FACS. Representative FACS analysis plots are shown that identify the hemogenic endothelial cell and HSPC phenotypes, and describe a methylcellulose-based assay for evaluating their blood forming potential on a clonal level.

Hematopoietic stem and progenitor cells (HSPC) derive from specialized (hemogenic) endothelial cells during development, yet little is known about the process by which some endothelial cells specify to become blood forming. We demonstrate a flow-cytometry based method allowing simultaneous isolation of hemogenic endothelial cells and HSPC from murine embryonic tissues.

Isolamento di cellule murine embrionali Hemogenic endoteliali

The specification of hemogenic endothelial cells from embryonic vascular endothelium occurs during brief developmental periods within distinct tissues, ...

Ricerca

Biologia dello sviluppo

Reprogramming Mouse Embryonic Fibroblasts with Transcription Factors to Induce a Hemogenic Program

This protocol details the induction of a hemogenic program in mouse embryonic fibroblasts (MEFs) via overexpression of transcription factors (TFs). We first designed a reporter screen using MEFs from human CD34-tTA/TetO-H2BGFP (34/H2BGFP) double transgenic mice. CD34+ cells from these mice label H2B histones with GFP, and cease labeling upon addition of doxycycline (DOX). MEFS were transduced with candidate TFs and then observed for the emergence of GFP+ cells that would indicate the acquisition of a hematopoietic or endothelial cell fate. Starting with 18 candidate TFs, and through a process of combinatorial elimination, we obtained a minimal set of factors that would induce the highest percentage of GFP+ cells. We found that Gata2, Gfi1b, and cFos were necessary and the addition of Etv6 provided the optimal induction. A series of gene expression analyses done at different time points during the reprogramming process revealed that these cells appeared to go through a precursor cell that underwent an endothelial to hematopoietic transition (EHT). As such, this reprogramming process mimics developmental hematopoiesis "in a dish," allowing study of hematopoiesis in vitro and a platform to identify the mechanisms that underlie this specification. This methodology also provides a framework for translation of this work to the human system in the hopes of generating an alternative source of patient-specific hematopoietic stem cells (HSCs) for a number of applications in the treatment and study of hematologic diseases.

The protocol described here details the induction of a hemogenic program in mouse embryonic fibroblasts via overexpression of a minimal set of transcription factors. This technology may be translated to the human system to provide platforms for future study of hematopoiesis, hematologic disease, and hematopoietic stem cell transplant.

Riprogrammazione fibroblasti embrionali di topo con fattori di trascrizione per indurre un programma Hemogenic

This protocol details the induction of a hemogenic program in mouse embryonic fibroblasts (MEFs) via overexpression of transcription factors (TFs). We ...

Identification Of Erythromyeloid Progenitors And Their Progeny In The Mouse Embryo By Flow Cytometry

Macrophages are professional phagocytes from the innate arm of the immune system. In steady-state, sessile macrophages are found in adult tissues where they act as front line sentinels of infection and tissue damage. While other immune cells are continuously renewed from hematopoietic stem and progenitor cells (HSPC) located in the bone marrow, a lineage of macrophages, known as resident macrophages, have been shown to be self-maintained in tissues without input from bone marrow HSPCs. This lineage is exemplified by microglia in the brain, Kupffer cells in the liver and Langerhans cells in the epidermis among others. The intestinal and colon lamina propria are the only adult tissues devoid of HSPC-independent resident macrophages. Recent investigations have identified that resident macrophages originate from the extra-embryonic yolk sac hematopoiesis from progenitor(s) distinct from fetal hematopoietic stem cells (HSC). Among yolk sac definitive hematopoiesis, erythromyeloid progenitors (EMP) give rise both to erythroid and myeloid cells, in particular resident macrophages. EMP are only generated within the yolk sac between E8.5 and E10.5 days of development and they migrate to the fetal liver as early as circulation is connected, where they expand and differentiate until at least E16.5. Their progeny includes erythrocytes, macrophages, neutrophils and mast cells but only EMP-derived macrophages persist until adulthood in tissues. The transient nature of EMP emergence and the temporal overlap with HSC generation renders the analysis of these progenitors difficult. We have established a tamoxifen-inducible fate mapping protocol based on expression of the macrophage cytokine receptor Csf1r promoter to characterize EMP and EMP-derived cells in vivo by flow cytometry.

While infiltrating macrophages are continuously recruited to adult tissues from circulating precursors, resident macrophages seed their tissue during development, where they are maintained without further input from progenitors. The progenitors for resident macrophages were recently identified. Here, we present methods for the genetic fate mapping of the resident macrophage progenitors.

Identificazione di progenitori eritromieloidi e loro progenie nell&#39;embrione del mouse dalla citometria del flusso

Macrophages are professional phagocytes from the innate arm of the immune system. In steady-state, sessile macrophages are found in adult tissues where ...

Direct Lineage Reprogramming of Adult Mouse Fibroblast to Erythroid Progenitors

Erythroid cell commitment and differentiation proceed through activation of a lineage-restricted transcriptional network orchestrated by a group of cell fate determining and maturing factors. We previously set out to define the minimal set of factors necessary for instructing red blood cell development using direct lineage reprogramming of fibroblasts into induced erythroid progenitors/precursors (iEPs). We showed that overexpression of Gata1, Tal1, Lmo2, and c-Myc (GTLM) can rapidly convert murine and human fibroblasts directly to iEPs that resemble bona fide erythroid cells in terms of morphology, phenotype, and gene expression. We intend that iEPs will provide an invaluable tool to study erythropoiesis and cell fate regulation. Here we describe the stepwise process of converting murine tail tip fibroblasts into iEPs via transcription factor-driven direct lineage reprogramming (DLR). In this example, we perform the reprogramming in fibroblasts from erythroid lineage-tracing mice that express the yellow fluorescent protein (YFP) under the control of the erythropoietin receptor gene (EpoR) promoter, enabling visualization of erythroid cell fate induction upon reprogramming. Following this protocol, fibroblasts can be reprogrammed into iEPs within five to eight days. 
While improvements can still be made to the process, we show that GTLM-mediated reprogramming is a rapid and direct process, yielding cells with properties of bona fide erythroid progenitor and precursor cells.

Here we present our protocol for producing induced erythroid progenitors (iEPs) from mouse adult fibroblasts using transcription factor-driven direct lineage reprogramming (DLR).

Diretto lignaggio riprogrammazione di fibroblasti di topo adulto ai progenitori eritroidi

Erythroid cell commitment and differentiation proceed through activation of a lineage-restricted transcriptional network orchestrated by a group of cell ...

Identification and Isolation of Burst-Forming Unit and Colony-Forming Unit Erythroid Progenitors from Mouse Tissue by Flow Cytometry

Early erythroid progenitors were originally defined by their colony-forming potential in vitro and classified into burst-forming and colony-forming &#34;units&#34; known as BFU-e and CFU-e. Until recently, methods for the direct prospective and complete isolation of pure BFU-e and CFU-e progenitors from freshly isolated adult mouse bone marrow were not available. To address this gap, a single-cell RNA-seq (scRNAseq) dataset of mouse bone marrow was analyzed for the expression of genes coding for cell surface markers. This analysis was combined with cell fate assays, allowing the development of a novel flow cytometric approach that identifies and allows the isolation of complete and pure subsets of BFU-e and CFU-e progenitors in mouse bone marrow or spleen. This approach also identifies other progenitor subsets, including subsets enriched for basophil/mast cell and megakaryocytic potentials. The method consists of labeling fresh bone marrow or spleen cells with antibodies directed at Kit and CD55. Progenitors that express both these markers are then subdivided into five principal populations. Population 1 (P1 or CFU-e, Kit+ CD55+ CD49fmed/low CD105med/high CD71med/high) contains all of the CFU-e progenitors and may be further subdivided into P1-low (CD71med CD150high) and P1-hi (CD71high CD150low), corresponding to early and late CFU-e, respectively; Population 2 (P2 or BFU-e, Kit+ CD55+ CD49fmed/low CD105med/high CD71low CD150high) contains all of the BFU-e progenitors; Population P3 (P3, Kit+ CD55+ CD49fmed/high CD105med/low CD150low CD41low) is enriched for basophil/mast cell progenitors; Population 4 (P4, Kit+ CD55+ CD49fmed/high CD105med/low CD150high CD41+) is enriched for megakaryocytic progenitors; and Population 5 (P5, Kit+ CD55+ CD49fmed/high CD105med/low CD150high CD41-) contains progenitors with erythroid, basophil/mast cell, and megakaryocytic potential (EBMP) and erythroid/ megakaryocytic/ basophil-biased multipotential progenitors (MPPs). This novel approach allows greater precision when analyzing erythroid and other hematopoietic progenitors and also allows for reference to transcriptome information for each flow cytometrically defined population.

Here, we describe a novel flow cytometric method for prospective isolation of early burst-forming unit erythroid (BFU-e) and colony-forming unit erythroid (CFU-e) progenitors directly from fresh mouse bone marrow and spleen. This protocol, developed based on single-cell transcriptomic data, is the first to isolate all the tissue's erythroid progenitors with high purity.

Identificazione e isolamento di progenitori eritroidi dell'unità burst-forming e dell'unità formante colonie da tessuto murino mediante citometria a flusso

Early erythroid progenitors were originally defined by their colony-forming potential in vitro and classified into burst-forming and colony-forming ...

Identification and Analysis of Mouse Erythroid Progenitors using the CD71/TER119 Flow-cytometric Assay

The study of erythropoiesis aims to understand how red cells are formed from earlier hematopoietic and erythroid progenitors. Specifically, the rate of red cell formation is regulated by the hormone erythropoietin (Epo), whose synthesis is triggered by tissue hypoxia. A threat to adequate tissue oxygenation results in a rapid increase in Epo, driving an increase in erythropoietic rate, a process known as the erythropoietic stress response. The resulting increase in the number of circulating red cells improves tissue oxygen delivery. An efficient erythropoietic stress response is therefore critical to the survival and recovery from physiological and pathological conditions such as high altitude, anemia, hemorrhage, chemotherapy or stem cell transplantation. 
The mouse is a key model for the study of erythropoiesis and its stress response. Mouse definitive (adult-type) erythropoiesis takes place in the fetal liver between embryonic days 12.5 and 15.5, in the neonatal spleen, and in adult spleen and bone marrow. Classical methods of identifying erythroid progenitors in tissue rely on the ability of these cells to give rise to red cell colonies when plated in Epo-containing semi-solid media. Their erythroid precursor progeny are identified based on morphological criteria. Neither of these classical methods allow access to large numbers of differentiation-stage-specific erythroid cells for molecular study. Here we present a flow-cytometric method of identifying and studying differentiation-stage-specific erythroid progenitors and precursors, directly in the context of freshly isolated mouse tissue. The assay relies on the cell-surface markers CD71, Ter119, and on the flow-cytometric 'forward-scatter' parameter, which is a function of cell size. The CD71/Ter119 assay can be used to study erythroid progenitors during their response to erythropoietic stress in vivo, for example, in anemic mice or mice housed in low oxygen conditions. It may also be used to study erythroid progenitors directly in the tissues of genetically modified adult mice or embryos, in order to assess the specific role of the modified molecular pathway in erythropoiesis.

A flow-cytometric method for identification and molecular analysis of differentiation-stage-specific murine erythroid progenitors and precursors, directly in freshly &#x2013;harvested mouse bone marrow, spleen or fetal liver. The assay relies on cell-surface markers CD71, Ter119, and cell size.

Identificazione e analisi dei mouse progenitori eritroidi utilizzando il CD71/TER119 Flow-citometria Assay

The study of erythropoiesis aims to understand how red cells are formed from earlier hematopoietic and erythroid progenitors. Specifically, the rate of ...

Biologia

Lentiviral-mediated Knockdown During Ex Vivo Erythropoiesis of Human Hematopoietic Stem Cells

Erythropoiesis is a commonly used model system to study cell differentiation. During erythropoiesis, pluripotent adult human hematopoietic stem cells (HSCs) differentiate into oligopotent progenitors, committed precursors and mature red blood cells 1. This process is regulated for a large part at the level of gene expression, whereby specific transcription factors activate lineage-specific genes while concomitantly repressing genes that are specific to other cell types 2. Studies on transcription factors regulating erythropoiesis are often performed using human and murine cell lines that represent, to some extent, erythroid cells at given stages of differentiation 3-5. However transformed cell lines can only partially mimic erythroid cells and most importantly they do not allow one to comprehensibly study the dynamic changes that occur as cells progress through many stages towards their final erythroid fate. Therefore, a current challenge remains the development of a protocol to obtain relatively homogenous populations of primary HSCs and erythroid cells at various stages of differentiation in quantities that are sufficient to perform genomics and proteomics experiments.
Here we describe an ex vivo cell culture protocol to induce erythroid differentiation from human hematopoietic stem/progenitor cells that have been isolated from either cord blood, bone marrow, or adult peripheral blood mobilized with G-CSF (leukapheresis). This culture system, initially developed by the Douay laboratory 6, uses cytokines and co-culture on mesenchymal cells to mimic the bone marrow microenvironment. Using this ex vivo differentiation protocol, we observe a strong amplification of erythroid progenitors, an induction of differentiation exclusively towards the erythroid lineage and a complete maturation to the stage of enucleated red blood cells. Thus, this system provides an opportunity to study the molecular mechanism of transcriptional regulation as hematopoietic stem cells progress along the erythroid lineage. 
Studying erythropoiesis at the transcriptional level also requires the ability to over-express or knockdown specific factors in primary erythroid cells. For this purpose, we use a lentivirus-mediated gene delivery system that allows for the efficient infection of both dividing and non-dividing cells 7. Here we show that we are able to efficiently knockdown the transcription factor TAL1 in primary human erythroid cells. In addition, GFP expression demonstrates an efficiency of lentiviral infection close to 90%. Thus, our protocol provides a highly useful system for characterization of the regulatory network of transcription factors that control erythropoiesis.

Lentiviral-mediated Knockdown During Ex Vivo Erythropoiesis of Human Hematopoietic Stem Cells

An ex vivo protocol to generate mature human red blood cells from hematopoietic stem/progenitors is described. Additionally we describe an efficient lentiviral-delivery method to knockdown the transcription factor TAL1 in primary erythroid cells. The efficiency of lentivirus mediated gene delivery is demonstrated using GFP expressing viruses.

Lentivirali-mediata Knockdown Durante Ex Vivo</emEritropoiesi> di cellule staminali emopoietiche

Erythropoiesis is a commonly used model system to study cell differentiation. During erythropoiesis, pluripotent adult human hematopoietic stem cells ...

Robust Generation of Hepatocyte-like Cells from Human Embryonic Stem Cell Populations

Despite progress in modelling human drug toxicity, many compounds fail during clinical trials due to unpredicted side effects. The cost of clinical studies are substantial, therefore it is essential that more predictive toxicology screens are developed and deployed early on in drug development (Greenhough et al 2010). Human hepatocytes represent the current gold standard model for evaluating drug toxicity, but are a limited resource that exhibit variable function. Therefore, the use of immortalised cell lines and animal tissue models are routinely employed due to their abundance. While both sources are informative, they are limited by poor function, species variability and/or instability in culture (Dalgetty et al 2009). Pluripotent stem cells (PSCs) are an attractive alternative source of human hepatocyte like cells (HLCs) (Medine et al 2010). PSCs are capable of self renewal and differentiation to all somatic cell types found in the adult and thereby represent a potentially inexhaustible source of differentiated cells. We have developed a procedure that is simple, highly efficient, amenable to automation and yields functional human HLCs (Hay et al 2008 ; Fletcher et al 2008 ; Hannoun et al 2010 ; Payne et al 2011 and Hay et al 2011). We believe our technology will lead to the scalable production of HLCs for drug discovery, disease modeling, the construction of extra-corporeal devices and possibly cell based transplantation therapies.

This article will focus on the generation of human hepatic endoderm from human embryonic stem cell populations.

Generazione robusta di epatociti-come le cellule da popolazioni di cellule staminali embrionali

Despite progress in modelling human drug toxicity, many compounds fail during clinical trials due to unpredicted side effects. The cost of clinical ...

Identification of a Murine Erythroblast Subpopulation  Enriched in Enucleating Events by Multi-spectral Imaging Flow Cytometry

Erythropoiesis in mammals concludes with the dramatic process of enucleation that results in reticulocyte formation. The mechanism of enucleation has not yet been fully elucidated. A common problem encountered when studying the localization of key proteins and structures within enucleating erythroblasts by microscopy is the difficulty to observe a sufficient number of cells undergoing enucleation.&#160;We have developed a novel analysis protocol using multiparameter high-speed cell imaging in flow (Multi-Spectral Imaging Flow Cytometry), a method that combines immunofluorescent microscopy with flow cytometry, in order to identify efficiently a significant number of enucleating events, that allows to obtain measurements and perform statistical analysis.
We first describe here two in vitro erythropoiesis culture methods used in order to synchronize murine erythroblasts and increase the probability of capturing enucleation at the time of evaluation.&#160;Then, we describe in detail the staining of erythroblasts after fixation and permeabilization in order to study the localization of intracellular proteins or lipid rafts during enucleation by multi-spectral imaging flow cytometry.&#160;Along with size and DNA/Ter119 staining which are used to identify the orthochromatic erythroblasts, we utilize the parameters &#8220;aspect ratio&#8221; of a cell in the bright-field channel that aids in the recognition of elongated cells and &#8220;delta centroid XY Ter119/Draq5&#8221; that allows the identification of cellular events in which the center of Ter119 staining (nascent reticulocyte) is far apart from the center of Draq5 staining (nucleus undergoing extrusion), thus indicating a cell about to enucleate.&#160;The subset of the orthochromatic erythroblast population with high delta centroid and low aspect ratio is highly enriched in enucleating cells.

The present protocol describes a novel method of identifying a population of enucleating orthochromatic erythroblasts by multi-spectral imaging flow cytometry, providing a visualization of the erythroblast enucleation process.

Identificazione di un Murine eritroblasto sottopopolazione Enriched in enucleare Eventi da Multi-spettrale Imaging Citometria a Flusso

Erythropoiesis in mammals concludes with the dramatic process of enucleation that results in reticulocyte formation. The mechanism of enucleation has not ...

Cell Type-specific Gene Expression Profiling in the Mouse Liver

Liver repopulation after injury is a crucial feature of mammals which prevents immediate organ failure and death after exposure of environmental toxins. A deeper understanding of the changes in gene expression that occur during repopulation could help identify therapeutic targets to promote the restoration of liver function in the setting of injuries. Nonetheless, methods to isolate specifically the repopulating hepatocytes are inhibited by a lack of cell markers, limited cell numbers, and the fragility of these cells. The development of translating ribosome affinity purification (TRAP) technology in conjunction with the Fah-/- mouse model to recapitulate repopulation in the setting of liver injury allows gene expression profiling of the repopulating hepatocytes. With TRAP, cell type-specific translating mRNA is rapidly and efficiently isolated. We developed a method that utilizes TRAP with affinity-based isolation of translating mRNA from hepatocytes that selectively express the green fluorescent protein (GFP)-tagged ribosomal protein (RP), GFP:RPL10A. TRAP circumvents the long time period required for fluorescence-activated cell sorting that could change the gene expression profile. Furthermore, since only the repopulating hepatocytes express the GFP:RPL10A fusion protein, the isolated mRNA is devoid of contamination from the surrounding injured hepatocytes and other cell types in the liver. The affinity-purified mRNA is of high quality and allows downstream PCR- or high-throughput sequencing-based analysis of gene expression.

Translating ribosome affinity purification (TRAP) enables rapid and efficient isolation of cell type-specific translating mRNA. Here, we demonstrate a method that combines hydrodynamic tail-vein injection in a mouse model of liver repopulation and TRAP to examine the expression profile of repopulating hepatocytes.

Profiling dell'espressione genica specifica del tipo di cella nel fegato del mouse

Liver repopulation after injury is a crucial feature of mammals which prevents immediate organ failure and death after exposure of environmental toxins. A ...

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

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