Questo lavoro è stato supportato da una sovvenzione di progetto pilota da CREH centro sponsorizzato dal NIEHS e dalla Fondazione nazionale di scienze naturali della Cina (No. 31572626).

Tutti gli esperimenti sugli animali sono stati eseguiti in conformità con tutte le pertinenti linee guida, regolamenti e agenzie di regolamentazione. Il protocollo in questione è stato effettuato sotto la guida e l'approvazione del istituzionale Animal Care e uso Committee (IACUC) della Texas A & M. Istituto per la medicina genomica.
1. soluzione preparazione
<ol><li>Diluire la soluzione salina bilanciata di Hank di 10 x 1 x con doppio distillata H2O e conservare a 4 ° C.</li>
	<li>Preparare la soluzione di isolamento aggiungendo HEPES (10 mM), MgCl2 (1 mM) e glucosio (5 mM). Regolare il pH a 7,4 e tenere sul ghiaccio.</li>
	<li>Preparare la soluzione di collagenasi da collagenasi tipo 4. Nota: In particolare, collagenasi tipo 4 contiene 160 U per mg di peso a secco. 1 g di collagenasi tipo 4 è diluito in 5 mL doppio distillata H2O con una concentrazione di 200 mg/mL. 2 mL della collagenosi diluita viene aggiunto alla soluzione di isolamento freddo ghiaccio 30 mL e 6 mL di soluzione di collagenasi viene trasferito in una provetta 50 mL per ogni mouse.</li>
	<li>Preparare la soluzione di lavaggio aggiungendo 1 mM CaCl2 per la soluzione di isolamento.</li>
	<li>Preparare la soluzione di purificazione con soluzione di sodio polysucrose freddo diatrizoate (1,1119 g/mL, 5 mL).</li>
	<li>Preparare 500 mL di terreno di coltura dell'isolotto con l'aggiunta di L-Glutammina (20 mM), penicillina (100 U/mL), streptomicina (100 µ g/mL) e siero bovino fetale (FBS) (10%) nel medium RPMI.</li>
	<li>Preparare la soluzione di riserva di DCFH-DA sciogliendo la polvere in acqua distillata a 200 µM e conservare a-20 ° C. Nota: Il ROS macchiatura soluzione viene preparato diluendo la soluzione di riserva di DCFH-DA alla concentrazione finale di 5 µM in RPMI. Questo reagente dovrebbe essere protetto dalla luce.</li>
</ol>2. preparazione chirurgica
<ol><li>Iniettare per via intraperitoneale (I.P.) un mouse con avertin (2,5% avertin, 0,4 mL/20 g). Dopo che il mouse è completamente anestetizzato e non risponde più a posteriori del piede pizzichi, eutanasia il mouse e spostare la cappa biologica.</li>
	<li>Posizionare il mouse eutanasizzato col lato addominale rivolto verso l'alto e spruzzare sulla pelle con etanolo al 70% per la sterilizzazione.</li>
	<li>Aprire la cavità addominale con un 1 cm U-incisione sulla parte superiore dell'addome e ritrarre la pelle in direzione rostrale sopra la cassa per esporre la cavità addominale.</li>
</ol>3. rimozione e l'aspersione del pancreas
<ol><li>Come illustrato nella Figura 1, trovare la posizione del ampulla. Utilizzare un paio di pinze curve per serrare il duodeno vicina alla posizione dello sfintere di Oddi. Utilizzare un altro paio di pinzetta per serrare la parete del duodeno per bloccare la via biliare nel duodeno. Nota: L'ampolla non è stata inserita in questo passaggio. Questo passaggio è destinato a bloccare la via biliare nel duodeno.</li>
	<li>Riposizionare il mouse con la testa prossimale e distale per quanto riguarda il ricercatore piedi.</li>
	<li>Trovare il dotto biliare comune e iniettare lentamente 3 mL di soluzione della collagenosi con una siringa di ago e 5 mL di 30 G. Assicurarsi che il dotto biliare comune e il pancreas sono gonfiati dopo l'iniezione.</li>
	<li>Rimuovere il pancreas dilatato usando la pinzetta e forbice per separarla da discendente del colon, intestino, stomaco e milza. Posizionare il pancreas in un tubo da 50 mL contenente 3 mL di soluzione di collagenasi e tenerlo sul ghiaccio.</li>
</ol>4. pancreas digestione
<ol><li>Collocare ciascuna provetta da 50 mL in bagnomaria a 37 ° C. Incubare per 15-20 minuti (il tempo varia con lo sforzo e l'età dei topi).</li>
	<li>Vibrare il tubo con un vortex.</li>
	<li>Girone 4-5 pancreas digerito in un colino grande lavandino sterile e utilizzare una paletta per rendere il pancreas cadere a pezzi accuratamente. Utilizzare una siringa di ago e 10ml 23g contenente la soluzione di lavaggio per pipettare con forza le cellule digerite fuori dallo schermo. Raccogliere la soluzione di lavaggio in un tubo da 50 mL.</li>
	<li>Centrifugare le provette a 97 x g a 4 ° C per 1 min e decantare il supernatante.</li>
	<li>Aggiungere 25 mL di soluzione di lavaggio in provette e risospendere il tessuto delicato nel Vortex. Rotazione verso il basso i tessuti a 97 x g a 4 ° C per 1 min e decantare il supernatante. Ripetere per 3 volte. Fare attenzione a non spostare il tessuto pellettato.</li>
</ol>5. purificazione degli isolotti
<ol><li>Aggiungere 10 mL di soluzione di purificazione al pellet di tessuto lavato e Risospendere delicatamente il contenuto.</li>
	<li>Sovrapposizione delicatamente 5 mL di soluzione di isolamento sulla soluzione di purificazione. Prestare attenzione a mantenere un'interfaccia liquida tagliente tra le due soluzioni.</li>
	<li>Centrifugare la provetta a 560 x g a 4 ° C per 15 min con accelerazione lenta e senza freno. Inserire la pipetta nell'interfaccia e raccogliere lo strato di isolotti in nuove provette da 50 mL.</li>
	<li>Lavare gli isolotti come descritto al punto 3.5.</li>
</ol>6. placcatura e trattamento delle cellule dell'isolotto
<ol><li>Risospendere le isolette in 10 mL di soluzione di cultura di isolotti, delicatamente mescolare bene e mettere 100 µ l/pozzetto con una pipetta multicanale per una piastra a 96 pozzetti. Posizionare bene circa 5 isolotti a 96.</li>
	<li>Posizionare la piastra nell'incubatore coltura tissutale per 12 h.</li>
	<li>Centrifugare (112 x g) la piastra a 96 pozzetti e rimuovere il terreno di coltura.</li>
	<li>Diluire i prodotti chimici ambientali nel terreno di coltura di isolotti. Aggiungere 100 µ l di ciascuno dei diluenti chimici in pozzetti separati della piastra. Risospendere le isolette in ogni pozzetto e incubare per 12 ore a 37 ° C (la concentrazione varia per i diversi prodotti chimici ambientali).</li>
</ol>7. ROS macchiatura e misurazione
<ol><li>Dopo il trattamento di isolotti, lavare con PBS 1X (200 µ l per ogni 96 pozzetti). Nota: La concentrazione delle sostanze chimiche è come segue: AFB1: 3 µM, atrazina: 100 µM, BaP: 10 µM, BPA: 100 µM, β-estrogeno, PCB126: 10 µM, nonilfenolo e BPA: 100 µM.</li>
	<li>Utilizzare N-acetil cisteina (NAC) come antiossidante per placare ROS. Aggiungere 5 mM di NAC per i diluenti chimici indotta da ROS e incubare per 12 ore a 37 ° C.</li>
	<li>Centrifugare la piastra a 96 pozzetti a 112 x g e incubare con soluzione di 5 µM di sonda fluorescente (H2-DCFH-DA dissolto nei media RPMI) a 37 ° C per 60 min.</li>
	<li>Lavare le cellule dell'isolotto trattate 3 volte con PBS e misurare la fluorescenza con un lettore di micropiastre a 488 nm. Nota: L'accumulo di DCF in cellule può essere misurata tramite un aumento nella fluorescenza a 530 nm quando il campione è eccitato a 488 nm.</li>
	<li>Eseguire il glucosio-stimolata dell'insulina secrezione (GSIS) dosaggio9 su xenobiotici che inducono ROS trattati isolette e isolotti non trattati per misurare gli effetti degli xenobiotici sulla funzione fisiologica degli isolotti pancreatici.</li>
</ol>

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Gli autori dichiarano di non avere nessun concorrenti interessi finanziari.

Raccogliendo la prova suggerisce che l'esposizione ai prodotti chimici ambientali svolge un ruolo importante nello sviluppo di T2DM. ROS indotta da xenobiotici è stato riconosciuto come un potenziale fattore eziologico che contribuiscono allo sviluppo di T2DM. Gli esseri umani sono esposti a una vasta gamma di prodotti chimici xenobiotici e c'è un grande bisogno di tecniche di ricerca romanzo di identificare in modo efficace le sostanze tossiche del pancreas e di studiare il meccanismo della tossicità specifica per le cellule pancreatiche.
In questo studio, basato su procedure pubblicate14, abbiamo sviluppato un protocollo per isolare gli isolotti pancreatici da mouse e schermo le cellule con prodotti chimici xenobiotici per danneggiamento indotto da stress ossidativo le cellule pancreatiche. Abbiamo anche utilizzare questa procedura per indagare le risposte tossiche specifiche pancreatiche indotte da composti xenobiotici. Per ottenere il pancreas da mouse, preferiamo usare avertin sopra altri anestesia perché non altera i livelli di glucosio nel sangue e non influisce il sistema vascolare del pancreas15,16,17. Abbiamo trovato che la fase di centrifugazione su gradiente di densità è critica per l'isolamento dell'isolotto con elevata purezza. Cura dovrebbe essere presa per ottenere il livello di distinto tra la fase di tampone sodio polysucrose e isolamento per ottenere un campione di isolotti puro, privo di detriti e di tessuti o cellule esocrini. Il metodo può essere utilizzato per l'analisi in vitro degli effetti chimici ambientali sulla fisiologia dell'isolotto pancreatico, ad esempio, il saggio GSIS (come mostrato nella Figura 3). Gli isolotti devono essere attentamente dispersa con ripetute dispensazione in celle separate per garantire il numero di cellulare in uniforme nella piastra di coltura 96-cellulare. Il metodo descritto qui combinato l'isolamento dell'isolotto e un'analisi rapida per la generazione di ROS e di conseguenza, è una schermata iniziale semplice ed efficace per i potenziali prodotti chimici danneggiano il pancreas.
Abbiamo usato la secrezione dell'insulina in risposta alla sfida del glucosio per confermare l'identità degli isolotti pancreatici isolati. La procedura è altamente adattabile per l'analisi dei cambiamenti nei parametri, tra cui la secrezione dell'insulina (Figura 3) e generazione di accampamento, in risposta a trattamenti xenobiotici18.

Aumento della prevalenza di T2DM è diventati una crisi sanitaria globale negli ultimi anni ponevano una seria minaccia alla salute pubblica1. Molti fattori sono stati trovati per essere causalmente collegato allo sviluppo di T2DM, tra i quali, ricorrenti risultati suggeriscono che un comune punto convergente per questi fattori è l'induzione di stress ossidativo che porta alla generazione di eccessivo ROS2 , 3.
Un ampio spettro di prodotti chimici ambientali compresi PCB, diossine e BaP è stato trovato per indurre stress ossidativo, che può alterare la funzione delle cellule β del pancreas e portare a insulino-resistenza e T2DM4. Anche se il livello fisiologico di ROS svolge un ruolo importante nelle funzioni cellulari, l'esposizione a ROS che supera la capacità del sistema antiossidante provoca il danno ai tessuti o cellule e conduce a malattie5. Le cellule β del pancreas esprimere un basso livello di enzima antiossidante e quindi sono un obiettivo sensibile per il danno ossidativo di sforzo-mediati6,7. L'esposizione cronica ad alti livelli di ROS è stato indicato per causare la disfunzione di cellula pancreatica indotta da stress5 così come la resistenza di insulina nel fegato e nel tessuto adiposo8.
L'obiettivo generale di questo progetto è quello di sviluppare un'analisi basata su celle a sostanze chimiche di schermo per loro potenziali diabetogeni basati su loro induzione del ROS in cellule pancreatiche. Il pancreas manca disintossicazione metabolica ed è un obiettivo sensibile per danni indotti da xenobiotici6,7. Pertanto, misurando direttamente i ROS generati nelle cellule del pancreas, questo test dovrebbe fornire un'approssimazione diretta della ferita indotta da prodotto nel pancreas. Per sviluppare questo metodo, abbiamo isolato isolotti pancreatici del topo, coltivate l'isolotto isolato sotto condizione di cultura delle cellule con sostanze chimiche e utilizzate la generazione di ROS indotta da sostanze chimiche come la lettura. Questa procedura è semplice ed efficace nell'identificazione di prodotti chimici che inducono ROS nell'isolato isolotto; può essere ulteriormente sviluppato per indagine dei meccanismi di tossicità che sono specifici per il pancreas in vitro.

<table><tbody><tr><td>10&amp;times;Hank&amp;rsquo;s balanced salt solution&amp;nbsp;</td><td>GIBCO</td><td>14185-052</td><td></td></tr><tr><td>Collagenase Type 4</td><td>Worthington Biochemical Corporation</td><td>CLS-4</td><td></td></tr><tr><td>polysucrose/sodium diatrizoate solution&amp;nbsp;</td><td>Sigma</td><td>10771</td><td></td></tr><tr><td>2&amp;rsquo;,7&amp;rsquo;-dichlorofluorescein (DCFH-DA)</td><td>Sigma</td><td>D6883-50MG</td><td></td></tr><tr><td>fluorescence microplate reader&amp;nbsp;</td><td>Biotek</td><td></td><td></td></tr><tr><td>L-glutamine</td><td>Sigma</td><td>G8540-25G</td><td></td></tr><tr><td>streptomycin</td><td>GIBCO</td><td>15140148</td><td></td></tr><tr><td>FBS</td><td>GIBCO</td><td>26140079</td><td></td></tr><tr><td>RPMI 1640</td><td>GIBCO</td><td>11875-085</td><td></td></tr><tr><td>avertin</td><td>Sigma</td><td>T48402-25G</td><td></td></tr><tr><td>Rat/Mouse Insulin ELISA Kit</td><td>Millipore</td><td>EZRMI-13K</td><td></td></tr><tr><td>Centrifuge</td><td>Sorval</td><td>Sorval RT7</td><td>for 96-well plate centrifuge</td></tr><tr><td>Microplate reader</td><td>Biotek</td><td>Epoch 2</td><td>for fluorescence reading</td></tr></tbody></table>

a murine pancreatic islet cell-based screening for diabetogenic environmental chemicals

L'esposizione a determinati prodotti chimici ambientali negli umani e negli animali è stato trovato per causare danno cellulare delle cellule β del pancreas che porterà allo sviluppo di diabete mellito di tipo 2 (T2DM). Anche se i meccanismi per il danno cellulare indotto da chimica β erano poco chiare e probabile che sia complessa, una scoperta ricorrente è che queste sostanze chimiche inducono lo sforzo ossidativo che porta alla generazione di specie di eccessiva reattive dell'ossigeno (ROS) che inducono danni alla la cella β. Per identificare potenziali diabetogeni prodotti chimici ambientali, abbiamo isolato le cellule di Langerhans dai topi C57BL/6 e cellule dell'isolotto coltivate in piastre per colture cellulari di 96 pozzetti; cellule dell'isolotto sono state dosate con prodotti chimici, quindi la generazione di ROS è stata rilevata da 2', 7'-diclorofluorescina (DCFH-DA) tintura fluorescente. Utilizzando questo metodo, abbiamo trovato che il bisfenolo A (BPA), Benzo [a] pirene (BaP) e policlorobifenili (PCB), potrebbe indurre elevati livelli di ROS, suggerendo che potenzialmente possono indurre danni in cellule dell'isolotto. Questo metodo dovrebbe essere utile per lo screening di xenobiotici diabetogeni. Inoltre, cellule dell'isolotto coltivate possono anche essere adattate per l'analisi in vitro della tossicità chimica-indotta in cellule pancreatiche.

Un Micrografo dell'isolotto isolato sano è illustrato nella Figura 2, in cui isolotti hanno una forma rotonda o ovale con relativamente uniforme dimensioni (anche se uniformità di dimensione può variare da ceppo a ceppo). Successivamente abbiamo studiato le funzioni pancreatiche in un'analisi in vitro isolando l'isolotto e stimolando la secrezione di insulina negli isolotti di cultura. La figura 3 Mostra la nostra analisi tipica del dosaggio GSIS da C57BL/6 isolotti di topo isolato indotto da 3,3 mM e 16,7 mM glucosio9.
Usando il metodo della piastra formato schermo, abbiamo identificato diversi xenobiotici che ha causato l'induzione significativa di ROS in cellule dell'isolotto (Figura 4). Abbiamo trattato gli isolotti isolati con diverse sostanze chimiche per 12 h e trovato quello di atrazina, BPA, BaP e PCB126, e β-estrogeno potrebbe causare induzione significativa di ROS in isolotti isolati10,11,12 , 13.
Anche se non è uguale all'induzione diabetogeni ROS, è ampiamente dimostrato che indica l'importante ruolo dei ROS nel causare danni per le funzioni fisiologiche delle cellule β del pancreas, che conduce a T2DM8. Di conseguenza, il valore del lavoro consiste nell'identificare questi ROS inducendo chimico come schermata iniziale. Inoltre, i composti identificati possono essere ulteriormente analizzato in vitro nel sistema di coltura cellulare di isole pancreatiche isolato descritto nel manoscritto. Abbiamo mostrato gli effetti degli xenobiotici che inducono ROS sulla secrezione di insulina glucosio-stimolante degli isolotti isolati, che brevemente forniscono dati diabetogeni per questi composti in esame. Isolotti pancreatici pretrattati con PCB126 e BPA ha mostrato una diminuzione significativa nella secrezione di insulina rispetto al gruppo di controllo (Figura 5).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57327/57327fig1v3.jpg"> Figura 1 : Procedura di aspersione del pancreas di mouse. La procedura prevede i passaggi seguenti: (1) trovare ampulla e utilizzare due coppie di pinzetta per morsetto ampulla. (2) inserire l'ago attraverso la bile comune. (3) lentamente iniettare 3 mL di brodo di soluzione di collagenasi nella siringa 5 mL. (4) raccogliere il pancreas dilatato a partire dal duodeno. 
 
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57327/57327fig2v3.jpg"> Figura 2 : Isolato isolotti topo. Il isolotti pancreatici del topo isolato nel mezzo di coltura sono mostrato. Barra della scala di 500 µm.
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57327/57327fig3v3.jpg"> Figura 3 : Secrezione insulinica glucosio-mediata degli isolotti pancreatici isolati. Secrezione insulinica glucosio-mediata dipendente dalla dose (1, 3.3 e 16,7 mM, trattati per 15 min) è stata misurata in isolotti isolati (media 5 isolotti per pozzetto), usando una mouse l'insulina ELISA kit. Barre di errore indicano le deviazioni standard. p < 0.05.
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57327/57327fig4v3.jpg"> Figura 4 : Induzione di ROS da xenobiotici in isolotti isolati da topi C57BL/6. Isolotti isolati (A) sono stati trattati per 12 h e macchiati con tintura di fluorescenza 2', 7'-diclorofluorescina (DCFH-DA) per 1 h. La fluorescenza è stata determinata da un lettore di fluorescenza. (B) la chimica indotta da ROS sono stati temprati da NAC (5 mM). (AFB1: 3 µM, atrazina: 100 µM, BaP: 10 µM, BPA: 100 µM, PCB126: 10 µM, nonilfenolo, BPA: 100 µM e NAC: 5 mM). Barre di errore indicano le deviazioni standard. p < 0.05. <a href="/files/ftp_upload/57327/57327fig4v3large.jpg" target="_blank">Clicca qui per visualizzare una versione più grande di questa figura.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57327/57327fig5v3.jpg"> Figura 5 : Xenobiotici effetti sulla secrezione insulinica glucosio-mediata degli isolotti isolati. Isolotti isolati sono stati pre-trattati con PCB126, β-estrogeno e BPA (4 h) e mantenuti in terreno di coltura dell'isolotto per 1 h. Il surnatante degli isolotti è stato raccolto per la misura dell'insulina di un'insulina di mouse commercialmente disponibili ELISA test. Barre di errore indicano le deviazioni standard. p < 0.05.

Watch this Scientific Journal Video about A Murine Pancreatic Islet Cell-based Screening for Diabetogenic Environmental Chemicals at JoVE.com

A Murine Pancreatic Islet Cell-based Screening for Diabetogenic Environmental Chemicals

Qui presentiamo un protocollo per isolare le cellule delle isole pancreatiche del mouse per lo screening di induzioni ROS dai xenobiotici al fine di identificare i potenziali prodotti chimici xenobiotici diabetogeni.

Uno Screening basati su cellule dell'isolotto pancreatico murino per prodotti chimici ambientali diabetogeni

Exposure to certain environmental chemicals in human and animals has been found to cause cellular damage of the pancreatic &#946; cells which will lead to ...

a-murine-pancreatic-islet-cell-based-screening-for-diabetogenic

Universidad San Sebastian

Research

JoVE Journal

Immunology and Infection

7.3K Views.  Hunan Agriculture University. Qui presentiamo un protocollo per isolare le cellule delle isole pancreatiche del mouse per lo screening di induzioni ROS dai xenobiotici al fine di identificare i potenziali prodotti chimici xenobiotici diabetogeni.

Video: A Murine Pancreatic Islet Cell-based Screening for Diabetogenic Environmental Chemicals

Murine Pancreatic Islet Isolation

Hi, I am Greg Zott. I'm with the UCSF Diabetes Center in the Bluestone Laboratory, and today I'm gonna show you the process for isolating mouse eyelets. The procedure involves the injection of a collagenase solution into the pancreas of a C3 H donor mouse, where we will then remove that pancreas, digest it away, purify the eyelets on a fial gradient, and then handpick them for ultimate transplant into the kidney capsule of a diabetic NOD mouse, Which will be our recipient.Before we start this procedure, we diluted our ATE solution in a modified Hanks buffer and we have adjusted the concentration specific for the strain of mouse that we're using the C3 H.We found digests better at a 0.8 mgs per mil collagenase solution, and we will use that to inject into the common bile duct to distend the pancreas.Performing. The procedure today Will be Pavo codre of the diabetes center. He will inject, open up the mouse, expose the the intestines, and then inject into the common bile duct.We will spray down the mouse with ethanol to keep the hair down, and then we will also verify that the mouse has been sacrificed properly with a toe pinch. Pavo will now open up the mouse and exposing the intestine and the pancreas with a midline incision. The diaphragm will also be cut to verify that the mouse will be sacrificed.Before we get started, I'd like to point out some of the important structures. The stomach is lying right here with the pancreas attached underneath into the duodenum and above. This is the liver where we'll find the gallbladder and the common bile duct, which you can see right here.So what Pavo will do next is he will isolate the small intestine, find where the common bile duct enters the small intestine. Once the intestine is exposed, we clamp on either side of the common bile duct with mosquito clamps. We find that this allows more collagenates to enter the pancreas while other groups try to direct the clamp on top of the common bile duct.We find that this is a better technique in allowing enzyme to enter the pancreas. This is a gentle procedure. You don't want to tear the bowel.You wanna allow the clamps to lie gently on either side of the common bile duct. Now we will find a gallbladder, and once the gallbladder's exposed, we will use that as a guide to injecting the collagenase into the common bile duct. Powell's using a 30 gauge needle with a five cc syringe containing three mills of collagenase solution.As he's entering the common bile duct, he's distending that duct with collagenase solution and then he travels down the common bile duct till he reaches near the intestine. And as he's going down, the enzyme solutions being pumped into the injected into the pancreas. Now that the pancreas is inflated with collagenase solution, Powell's gonna remove the hemostats and then remove the pancreas from the the mouse carefully tearing it away from the intestine.He removes it from the stomach. Okay, and then using the spleen as a handle, he lifts up the pancreas and then slowly snips it away in the common bile duct, and that's it. Pancreas is laid out and then the spleen is removed, and there he's removing the meso enteric tissue, and then the pancreas is placed in a two mill collagenase solution and a sterilized glass vial and it's placed back on Ice.The isolated pancreas that we put into the glass vials will now be placed into a 37 degree water bath for approximately 17 minutes. We placed them into a 50 mil conical rack so that they don't float up. Once during the bath, the timer starts and the digestion begins.Once the digestion time is completed, vials are removed, and then they are shaken and disrupted gently. And once the tissue starts falling apart, the vial is then placed on ice. A sterile screen is placed over a 400 mil beaker that contains washing buffer.The pancreas digest is then carefully poured over the screen into the wash buffer. For demonstration purposes, the hood has been turned off and the glass of the hood has been raised so we could see what we're doing. Once the pancreas digest is poured into the beaker, the vials are rinsed with the same washing buffer and the wash buffer placed over the screen.We have a syringe filled with washing buffer. We will use that to forcefully wash the tissue through the screen. The idea is to release any loose eyelets that are unattached to the matrix, but leaving the membranes and the undigested tissue on the screen.And when you're finished washing a tissue, this is what you usually See at the end of the procedure. The Pancreas tissue that's in the bottom of the tube will now be transferred to two 50 mil conical, and the tissue will be washed, the tissue's mixed evenly, and then distributed evenly so that we have a equal pellet volume in each tube. The beaker is now rinsed with more washing buffer.The sides are rinse so that you get all tissue that is entered the beaker again. Then it's equally distributed between each two, both 50 mil. Conical then are topped off with wash buffer.The tissue is inverted several times and then placed into a centrifuge. This is a quick spin. The centrifuge is allowed to reach a thousand RPM and then is turned off.The tissue at this time is very S eyelets are very sensitive, and you don't want to over compact them. The tubes are removed and we will do this wash step three more times. This is the end of the third wash.The components of the 50 mil conical tube are transferred to the 15 conical tube and centrifuge for a thousand RP M and then stopped. The supernat will be removed and the first part of the FI Call will be started. We are at the step where we Have our pelleted di pancreas digest.We'll resuspend that tissue so it's nice and loose to the pellets. We'll add the first density gradient, which is 1 1 0 8. We'll add five mils to each tube.The pellet is then mixed thoroughly in each of the gradients. It's important that you get good tissue distribution in your heaviest gradient. Now we will layer two mils of 1 0 9 6 density.We will then on top of that, layer two mils of 1 0 6 9 density, and then on top of that 1 0 3 7 density. It's important while you're layering the densities that you don't mix. Then all the layers have been added to the tube.And you can see this is the top of 1 1 0 8, the top of 9 1 0 9 6, the top of 1 0 6 9 and the top of 1 0 3 7. And you could see the tissue is already starting to move to its proper density even without centri fusion. The fial gradients are brought up to speed at 1800 RPM for 15 minutes, and remember to keep the brake off after the tubes are removed from the centrifuge.You can see between the 0 0 9 6 and 0 0 7 layer, there's a nice band of eyelet tissue Pablo's. Now removing the 0 3 7 layer to remove any tissue debris and DNA that might have been released during the processing. Using a sterile plastic pasture pipette, he will now remove the islet layer and transfer them to a 50 mil conical containing 25 mils of wash buffer.You want do this step quickly because fol is toxic to eyelets. We actually removed the entire 0 6 9 and 0 9 6 layer. Pavo cuts the top of the plastic pasture pipette and rinses it with wash buffer.The eyelets are then centrifuge like we centrifuge previously. Centrifuge is brought up to a Thousand RPM and then we stop it and We aspirate off. The supernatant eyelets will be washed three times with wash media.So we just completed the eyelid Isolation process we took from the digest to the fol gradient to the purified eyelets after our third wash with wash buffer, we resuspended the eyelets in our RPMI media and we played it in a tissue culture plate. These eyelets are now ready for in vitro assays or in vivo preps like eyelet Transplant.

Murino pancreatica isolamento Islet

Ricerca

Biologia

Scaffold-supported Transplantation of Islets in the Epididymal Fat Pad of Diabetic Mice

Islet transplantation has been clinically proven to be effective at treating type 1 diabetes. However, the current intrahepatic transplantation strategy may incur acute whole blood reactions and result in poor islet engraftment. Here, we report a robust protocol for the transplantation of islets at the extrahepatic transplantation site-the epididymal fat pad (EFP)-in a diabetic mouse model. A protocol to isolate and purify islets at high yields from C57BL/6J mice is described, as well as a transplantation method performed by seeding islets onto a decellularized scaffold (DCS) and implanting them at the EFP site in syngeneic C57BL/6J mice rendered diabetic by streptozotocin. The DCS graft containing 500 islets reversed the hyperglycemic condition within 10 days, while the free islets without DCS required at least 30 days. The normoglycemia was maintained for up to 3 months until the graft was explanted. In conclusion, DCS enhanced the engraftment of islets into the extrahepatic site of the EFP, which could easily be retrieved and might provide a reproducible and useful platform for investigating the scaffold materials, as well as other transplantation parameters required for a successful islet engraftment.

This protocol demonstrates murine islet isolation and seeding onto a decellularized scaffold. Scaffold-supported islets were transplanted into the epididymal fat pad of streptozotocin (STZ)-induced diabetic mice. Islets survived at the transplantation site and reversed the hyperglycemic condition.

Il trapianto di isole nel supporto del grasso epididimico dei topi diabetici

Islet transplantation has been clinically proven to be effective at treating type 1 diabetes. However, the current intrahepatic transplantation strategy ...

Bioingegneria

Leprdb Mouse Model of Type 2 Diabetes: Pancreatic Islet Isolation and Live-cell 2-Photon Imaging Of Intact Islets

Type 2 diabetes is a chronic disease affecting 382 million people in 2013, and is expected to rise to 592 million by 2035 1. During the past 2 decades, the role of beta-cell dysfunction in type 2 diabetes has been clearly established 2. Research progress has required methods for the isolation of pancreatic islets. The protocol of the islet isolation presented here shares many common steps with protocols from other groups, with some modifications to improve the yield and quality of isolated islets from both the wild type and diabetic Leprdb (db/db) mice. A live-cell 2-photon imaging method is then presented that can be used to investigate the control of insulin secretion within islets.

Leprdb Mouse Model of Type 2 Diabetes: Pancreatic Islet Isolation and Live-cell 2-Photon Imaging Of Intact Islets

We present here a protocol for the isolation of islets from the mouse model of type 2 diabetes, Leprdb and details of a live-cell assay for measurement of insulin secretion from intact islets that utilizes 2 photon microscopy.

LEPR<sup&gt; Db</sup&gt; Mouse Modello di diabete di tipo 2: pancreas isolamento Islet e live-cella 2-Photon Imaging di isolotti Intact

Type 2 diabetes is a chronic disease affecting 382 million people in 2013, and is expected to rise to 592 million by 2035 1. During the past 2 decades, ...

Medicina

Intraportal Transplantation of Pancreatic Islets in Mouse Model

Pancreatic islet transplantation to reduce hyperglycemia is highly successful in rodents with chemically-induced diabetes. The most common transplantation site in experimental islet transplantation is the kidney capsule. However, as less is known about the interaction of pancreatic islets with blood constituents, it also makes sense to utilize the portal vein approach in experimental islet transplantation.
This protocol demonstrates an intraportal islet transplantation technique in NMRI nude mice. Streptozotocin (180 mg/kg) is injected intraperitoneally to induce hyperglycemia in recipient mice. They are considered as diabetic at a non-fasting blood glucose level greater than 20 mmol/L. One day prior to transplantation, mouse pancreatic islets are isolated from the donor pancreas by collagenase digestion; a minimum of 350 islets are utilized per diabetic recipient. Depending upon the islet isolation yield, two or more donor mice are utilized per recipient. After overnight culture at 37 &#176;C, islets are administered into the recipient liver via the portal vein. After surgery, the mice are protected in red Makrolon houses and observed until are awake. This protocol maintains glycemic control for 120 days in syngeneic mice and 15 days in allogeneic mice.

Pancreatic islet transplantation is a way to achieve normoglycemia in type 1 diabetes. This article focuses on the transplantation technique through the intraportal route to maintain normal glucose levels in diabetic mice.

Intraportal trapianto di isole pancreatiche nel modello del topo

Pancreatic islet transplantation to reduce hyperglycemia is highly successful in rodents with chemically-induced diabetes. The most common transplantation ...

A Method for Mouse Pancreatic Islet Isolation and Intracellular cAMP Determination

Uncontrolled glycemia is a hallmark of diabetes mellitus and promotes morbidities like neuropathy, nephropathy, and retinopathy. With the increasing prevalence of diabetes, both immune-mediated type 1 and obesity-linked type 2, studies aimed at delineating diabetes pathophysiology and therapeutic mechanisms are of critical importance. The &#946;-cells of the pancreatic islets of Langerhans are responsible for appropriately secreting insulin in response to elevated blood glucose concentrations. In addition to glucose and other nutrients, the &#946;-cells are also stimulated by specific hormones, termed incretins, which are secreted from the gut in response to a meal and act on &#946;-cell receptors that increase the production of intracellular cyclic adenosine monophosphate (cAMP). Decreased &#946;-cell function, mass, and incretin responsiveness are well-understood to contribute to the pathophysiology of type 2 diabetes, and are also being increasingly linked with type 1 diabetes. The present mouse islet isolation and cAMP determination protocol can be a tool to help delineate mechanisms promoting disease progression and therapeutic interventions, particularly those that are mediated by the incretin receptors or related receptors that act through modulation of intracellular cAMP production. While only cAMP measurements will be described, the described islet isolation protocol creates a clean preparation that also allows for many other downstream applications, including glucose stimulated insulin secretion, [3H]-thymidine incorporation, protein abundance, and mRNA expression.

Assaying in vitro &#946;-cell function using isolated mouse islets of Langerhans is an important component in the study of diabetes pathophysiology and therapeutics. While many&#160;downstream applications are available, this protocol specifically describes the measurement of intracellular cyclic adenosine monophosphate (cAMP) as an essential parameter determining &#946;-cell function.

Un metodo per l&#39;isolamento del mouse isole pancreatiche e intracellulare cAMP Determinazione

Uncontrolled glycemia is a hallmark of diabetes mellitus and promotes morbidities like neuropathy, nephropathy, and retinopathy. With the increasing ...

Observing Islet Function and Islet-Immune Cell Interactions in Live Pancreatic Tissue Slices

Live pancreatic tissue slices allow for the study of islet physiology and function in the context of an intact islet microenvironment. Slices are prepared from live human and mouse pancreatic tissue embedded in agarose and cut using a vibratome. This method allows for the tissue to maintain viability and function in addition to preserving underlying pathologies such as type 1 (T1D) and type 2 diabetes (T2D). The slice method enables new directions in the study of the pancreas through the maintenance of the complex structures and various intercellular interactions that comprise the endocrine and exocrine tissues of the pancreas. This protocol demonstrates how to perform staining and time-lapse microscopy of live endogenous immune cells within pancreatic slices along with assessments of islet physiology. Further, this approach can be refined to discern immune cell populations specific for islet cell antigens using major histocompatibility complex-multimer reagents.

This study presents the application of live pancreatic tissue slices to the study of islet physiology and islet-immune cell interactions.

Osservare la funzione delle isole e le interazioni isolo-cellule immunitarie nelle fette di tessuto pancreatico vivo

Live pancreatic tissue slices allow for the study of islet physiology and function in the context of an intact islet microenvironment. Slices are prepared ...

Immunologia e infezioni

Visualization of Endogenous Mitophagy Complexes In Situ in Human Pancreatic Beta Cells Utilizing Proximity Ligation Assay

Mitophagy is an essential mitochondrial quality control pathway, which is crucial for pancreatic islet beta cell bioenergetics to fuel glucose-stimulated insulin release. Assessment of mitophagy is challenging and often requires genetic reporters or multiple complementary techniques not easily utilized in tissue samples, such as primary human pancreatic islets. Here we demonstrate a robust approach to visualize and quantify formation of key endogenous mitophagy complexes in primary human pancreatic islets. Utilizing the sensitive proximity ligation assay technique to detect interaction of the mitophagy regulators NRDP1 and USP8, we are able to specifically quantify formation of essential mitophagy complexes in situ. By coupling this approach to counterstaining for the transcription factor PDX1, we can quantify mitophagy complexes, and the factors that can impair mitophagy, specifically within beta cells. The methodology we describe overcomes the need for large quantities of cellular extracts required for other protein-protein interaction studies, such as immunoprecipitation (IP) or mass spectrometry, and is ideal for precious human islet&#160;samples generally not available in sufficient quantities for these approaches. Further, this methodology obviates the need for flow sorting techniques to purify beta cells from a heterogeneous islet population for downstream protein applications. Thus, we describe a valuable protocol for visualization of mitophagy highly compatible for use in heterogeneous and limited cell populations.

This protocol outlines a method for quantitative analysis of mitophagy protein complex formation specifically in beta cells from primary human islet samples. This technique thus allows analysis of mitophagy from limited biological material, which are crucial in precious human pancreatic beta cell samples.

Visualizzazione di complessi mitogeni endogeni in Situ in cellule beta pancreatiche umane utilizzando la generazione di testdi di ligazione di prossimità

Mitophagy is an essential mitochondrial quality control pathway, which is crucial for pancreatic islet beta cell bioenergetics to fuel glucose-stimulated ...

Inguinal Subcutaneous White Adipose Tissue (ISWAT) Transplantation Model of Murine Islets

Pancreatic islet transplantation is a well-established therapeutic treatment for type 1 diabetes. The kidney capsule is the most commonly used site for islet transplantation in rodent models. However, the tight kidney capsule limits the transplantation of sufficient islets in large animals and humans. The inguinal subcutaneous white adipose tissue (ISWAT), a new subcutaneous space, was found to be a potentially valuable site for islet transplantation. This site has better blood supply than other subcutaneous spaces. Moreover, the ISWAT accommodates a larger islet mass than the kidney capsule, and transplantation into it is simple. This manuscript describes the procedure of mouse islet isolation and transplantation in the ISWAT site of syngeneic diabetic mouse recipients. Using this protocol, murine pancreatic islets were isolated by standard collagenase digestion and a basement membrane matrix hydrogel was used for fixing the purified islets in the ISWAT site. The blood glucose levels of the recipient mice were monitored for more than 100 days. Islet grafts were retrieved at day 100 after transplantation for histological analysis. The protocol for islet transplantation in the ISWAT site described in this manuscript is simple and effective.

Inguinal Subcutaneous White Adipose Tissue ISWAT Transplantation Model of Murine Islets

In this protocol, a method of murine islet isolation and transplantation into the inguinal subcutaneous white adipose tissue is described. Isolated syngeneic murine islets are transplanted into a murine recipient using a basement membrane hydrogel. The blood glucose level of the recipients is monitored, and histology analysis of the islet grafts is performed.

Modello di trapianto di Murine (ISWAT) del tessuto adiposo sottocutaneo inguinale (ISWAT)

Pancreatic islet transplantation is a well-established therapeutic treatment for type 1 diabetes. The kidney capsule is the most commonly used site for ...

A Simple High Efficiency Protocol for Pancreatic Islet Isolation from Mice

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other important biological functions. The islets primarily consist of five types of hormone-secreting cells: &#945; cells secrete glucagon, &#946; cells secrete insulin, &#948; cells secrete somatostatin, &#949; cells secrete ghrelin, and PP cells secrete pancreatic polypeptide. Sixty to 80% of the cells in the islets are &#946; cells, which are the most important cell population to study insulin secretion. Pancreatic islets are a crucial model system to study ex vivo insulin secretion. Acquiring high quality islets is of great importance for diabetes research. Most islet isolation procedures require technically difficult to access site of collagenase injection, harsh and complex digestion procedures, and multiple density gradient purification steps. This paper features a simple high yield mouse islet isolation method with detailed descriptions and realistic demonstrations, showing the following specific steps: 1) injection of collagenase P at the ampulla of Vater, a small area joining the pancreatic duct and the common bile duct, 2) enzymatic digestion and mechanical separation of the exocrine pancreas, and 3) a single gradient purification step. The advantages of this method are the injection of digestive enzyme using the more accessible ampulla of Vater, more complete digestion using combination of enzymatic and mechanical approaches, and a simpler single gradient purification step. This protocol produces approximately 250&#8212;350 islets per mouse; and islets are suitable for various ex vivo studies. Possible caveats of this procedure are potentially damaged islets due to enzymatic digestion and/or prolonged gradient incubation, all of which can be largely avoided by careful ad justification of incubation time.

This islet isolation protocol described a novel route of collagenase injection to digest the exocrine tissue and a simplified gradient procedure to purify the islets from mice. It involves enzymatic digestion, gradient separation/purification, and islet hand-picking. Successful isolation can yield 250&#8211;350 high quality and fully functional islets per mouse.

Un semplice protocollo ad alta efficienza per l'isolamento delle isolozioni pancreatiche dai topi

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other ...

Imaging Calcium Dynamics in Subpopulations of Mouse Pancreatic Islet Cells

Pancreatic islet hormones regulate blood glucose homeostasis. Changes in blood glucose induce oscillations of cytosolic calcium in pancreatic islet cells that trigger secretion of three main hormones: insulin (from &#946;-cells), glucagon (&#945;-cells) and somatostatin (&#948;-cells). &#946;-Cells, which make up the majority of islet cells and are electrically coupled to each other, respond to the glucose stimulus as one single entity. The excitability of the minor subpopulations, &#945;-cells and &#948;-cells (making up around 20% (30%) and 4% (10%) of the total rodent1 (human2) islet cell numbers, respectively) is less predictable and is therefore of special interest.
Calcium sensors are delivered into the peripheral layer of cells within the isolated islet. The islet or a group of islets is then immobilized and imaged using a fluorescence microscope. The choice of the imaging mode is between higher throughput (wide-field) and better spatial resolution (confocal). Conventionally, laser scanning confocal microscopy is used for imaging tissue, as it provides the best separation of the signal between the neighboring cells. A wide-field system can be utilized too, if the contaminating signal from the dominating population of &#946;-cells is minimized.
Once calcium dynamics in response to specific stimuli have been recorded, data are expressed in numerical form as fluorescence intensity vs. time, normalized to the initial fluorescence and baseline-corrected, to remove the effects linked to bleaching of the fluorophore. Changes in the spike frequency or partial area under the curve (pAUC) are computed vs. time, to quantify the observed effects. pAUC is more sensitive and quite robust whereas spiking frequency provides more information on the mechanism of calcium increase.
Minor cell subpopulations can be identified using functional responses to marker compounds, such as adrenaline and ghrelin, that induce changes in cytosolic calcium in a specific populations of islet cells.

Here, we present a protocol for imaging and quantifying calcium dynamics in heterogeneous cell populations, such as pancreatic islet cells. Fluorescent reporters are delivered into the peripheral layer of cells within the islet, which is then immobilized and imaged, and per-cell analysis of the dynamics of fluorescence intensity is performed.

Imaging calcio Dynamics in sottopopolazioni di cellule di islet pancreatica del topo

Pancreatic islet hormones regulate blood glucose homeostasis. Changes in blood glucose induce oscillations of cytosolic calcium in pancreatic islet cells ...

Uno Screening basati su cellule dell'isolotto pancreatico murino per prodotti chimici ambientali diabetogeni

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