We would like to acknowledge Susan Gray and Umadevi Chalasani for their help with technical aspects of the hepatocyte isolation protocol. This work was supported by NIDDK grant 5R01DK089185 (to M.P. Cooper) and the DERC Pilot and Feasibility Program at UMMS (to M.P. Cooper).

Tutti sperimentazione animale deve essere effettuata in conformità con le normative locali e federali e con l&#39;approvazione di un IACUC e radioprotezione amministrazione istituzionale. 1. Preparazione <ol><li> Alcuni giorni prima del test, scongelare il flacone da 500 ml di fegato Digest Medium (LDM) e ricongelare ~ 35 ml aliquote in 50 ml provette coniche. Conservare a -20 ° C fino al momento dell&#39;uso. </li><li> Un giorno prima del test, pre-sterilizzare strumenti di dissezione puliti in autoclave. </li><li> Il giorno del test, trattare la quantità necessaria di piastre di coltura a 24 pozzetti con collagene. <ol><li> Mescolare 1 parte di 3 mg / ml di collagene coda di ratto con 50 parti di PBS. Aggiungere circa 500 ml in ciascun pozzetto di una piastra da 24 pozzetti e incubare per 3-5 minuti a temperatura ambiente (RT). Rimuovere il collagene e lasciare asciugare la piastra all&#39;aria in cappuccio. Ripetere almeno una volta in più. Nota: Rivestimento collagene può essere effettuata fino a una settimana a annuncioVance e piatti conservati a 4 ° C sigillato in involucro di plastica. </li></ol></li><li> Preparare LDM per l&#39;analisi: Scongelare LDM e caldo a 37 ° C e aggiustare il pH a 7,4 con 1 N KOH. Filtro utilizzando 0,2 micron siringa filtro e posto in un ricircolo 42 ° C bagnomaria. </li><li> Caldo 25 ml di fegato di perfusione medio a 42 ° C a bagnomaria. Ricircolo </li><li> Preparare 90% di silice colloidale con una soluzione di polivinilpirrolidone rivestita: Aggiungere 1 ml di DPBS 10x a 9 ml di silice colloidale rivestite con polivinilpirrolidone. Regolare il pH a 7,4 con 0,1 N HCl. Filtrare con un filtro a siringa da 0,2 micron sterile. Conservare a temperatura ambiente. </li><li> Caldo placcatura medio a 37 ° C. </li></ol> 2. Isolamento di mouse primario Epatociti <ol><li> Impostare pompa peristaltica, tubi, e la tabella dissezione: Sterilizzare tubi da vampate di calore con 5 ml etanolo al 70% in acqua distillata, seguita da 10 ml di acqua sterile. Mettere il tubo in fegato perfusione Medium e pompa eseguire per riempireintera lunghezza del tubo. </li><li> Sacrifica il mouse con il metodo istituzionalmente approvato. </li><li> Sezionare aperto della cavità addominale: Spruzzare l&#39;addome del mouse liberamente con il 70% di etanolo. Utilizzando le forbici blunt-end, fare una incisione mediana attraverso il derma la lunghezza dell&#39;addome e riflettono lateralmente. Eseguire un&#39;incisione simile nel peritoneo per esporre le viscere. <ol><li> Utilizzando un corpo contundente, spostare dolcemente gli intestini per esporre la vascolarizzazione addominale Individuare il addominale vena cava inferiore (IVC) e posizionare una sutura sotto il vaso sanguigno, distale alla vena renale </li></ol></li><li> Distale alla sutura, posizionare un ago e catetere nel IVC, farlo avanzare oltre il livello della sutura. Con l&#39;ago ancora nel luogo, cravatta la sutura intorno al catetere per tenerlo in posizione. Rimuovere con cautela l&#39;ago. Se fatto correttamente, il sangue con flusso attraverso il catetere. </li><li> Usando una pipetta, riempire l&#39;area rimanente nel catetere con mezzo di perfusione, assicurandoche l&#39;aria non sia presente. Con grande cura, collegare il tubo al catetere. </li><li> Sezionare aperto la cavità polmonare: riflettere delicatamente i lobi del fegato superiori per esporre il diaframma. Forare con attenzione il diaframma con le forbici affilate punte, poi fare una incisione laterale per esporre la cavità pleurica, avendo cura di evitare la cistifellea e vascolare pleurico. Posizionare un morsetto bulldog intorno al torace vena cava inferiore solo prossimale alla vena epatica. </li><li> Tagliare la vena porta e accendere la pompa a 3 - 4 ml / min. Profumato fegato con fegato di perfusione medio per 5 minuti con circa 20 ml di terreno di perfusione. Nota: Il fegato deve cambiare immediatamente dal rosso al grigio / marrone chiaro. Se porzioni di fegato rimangono rossa, questo probabilmente indica scarsa perfusione, e la probabilità di isolamento di successo è notevolmente diminuita. Durante la perfusione, essere attenti a garantire il supporto non si esaurisce e che bolle entrano nel tubo. </li><li> Dopo la 5 min di incubazione, fermatala pompa e il tubo di trasferimento Fegato Digest Medium. Riavviare la pompa e perfusione del fegato per altri 10 - 15 minuti (finché il terreno è esaurito). </li><li> Al termine della perfusione, fermare la pompa. Il fegato dovrebbe avere un colore rosato e apparire in qualche modo allargata. Asportare il fegato da un&#39;attenta dissezione. Rimuovere la cistifellea e trasferire il fegato a 10 centimetri piatto di coltura di tessuti. </li><li> In un armadio biosicurezza, aggiungere 10 ml di placcatura medio (Tabella 1) al fegato. Raschiare delicatamente il fegato utilizzando sia pinze o un bisturi per rimuovere le epatociti. Filtrare la sospensione con un colino cella di 100 micron e trasferimento in una provetta da 50 ml. Lavare la piastra con altri 10 ml di placcatura medio e piscina in tubo conico da 50 ml. </li><li> Agglomerare le cellule per centrifugazione per 5 minuti a 350 xg, a 4 ° C. </li><li> Aspirare a medio e risospendere pellet in 10 ml di placcatura medio e aggiungere 10 ml di 90% di silice colloidale rivestito con Polyvinylpyrrolidone. Mescolare delicatamente e centrifugare come al punto 2.11. Dopo centrifugazione, uno strato di cellule morte sarà galleggiano sulla superficie della miscela, mentre le cellule vive si sedimentare sul fondo. </li><li> Aspirare le cellule morte e le medie. Lavare 2 volte con 20 ml di placcatura Medium, centrifuga come a 2.11. </li><li> Risospendere le cellule in 10 ml di placcatura Media. Contare le celle con un emocitometro e posizionare 9 x 10 4 cellule / pozzetto in 24 pozzetti piatti collagene trattati cultura. Incubare a 37 ° C tessuto cultura incubatore per 2 ore. Ogni piastra può essere utilizzata sia per il saggio Fatty Acid ossidazione o il dosaggio Lipogenesi. </li><li> Facoltativamente, modificare pozzetti Manutenzione Medium (Tabella 1) e cultura a 37 ° C. Le celle possono essere coltivate per 2 - 3 giorni senza influenzare i risultati del test. </li></ol> 3. acidi grassi ossidazione Assay Attenzione: L&#39;uso di radioattività può essere pericoloso. Tutti gli acquisti, lo stoccaggio, la movimentazione, e disposal di materiale radioattivo deve essere effettuata nel rispetto, statali e regolamenti e linee guida federali istituzionali. <ol><li> 16 - 20 ore prima del dosaggio, lavare le cellule 2 volte con PBS caldo. Modificare le cellule di siero Starvation mezzo privo di siero (Tabella 1) con 20 nM glucagone e incubare una notte a 37 ° C. Nota: Poiché siero fetale bovino contiene una concentrazione sconosciuta di ormoni metabolici (per esempio insulina, glucagone), siero morire di fame le cellule per rimuovere eventuali effetti confondenti questa può avere sul dosaggio. Le cellule sono vitali nel siero fame medio per&gt; 24 ore. Trattamento glucagone è usato per stimolare ossidazione degli acidi grassi all&#39;interno epatociti. </li><li> La mattina del saggio, preparare preincubazione medio: Risospendere una quantità appropriata di sodio palmitato in acqua ultrapura per ottenere una soluzione 100 mM e si riscalda a 70 ° C per 10 min. Nel frattempo, preparare la quantità necessaria (0,5 ml per pozzetto di una piastra da 24 pozzetti)di DMEM con 25 mM HEPES, 1% BSA Frazione V, e 20 nM glucagone. Riscaldare a 37 ° C. <ol><li> Una volta solubilizzato, palmitato aggiungere ad una concentrazione finale di 250 mM al mezzo. Cambiare epatociti di pre-incubazione medio e incubare a 37 ° C per 2 ore. Prenota alcuni pre-incubazione medio a 37 ° C per un uso successivo. </li></ol></li><li> Durante l&#39;incubazione, asciugare una quantità appropriata di 14 C-palmitato (0,5 pCi / pozzetto) per evaporazione sotto azoto. <ol><li> Ad esempio, per misurare 24 campioni in una piastra a 24 pozzetti, trasferire 120 ml di 0,1 pCi / ml 14 C-palmitato in una provetta da 1,5 ml. Lentamente si evapora il solvente etanolo soffiando gas azoto sulla soluzione da una distanza di 3-5 cm in una cappa aspirante. Il solvente deve evaporare in circa 30 - 40 min, lasciando asciutta 14 C-palmitato nel fondo della provetta. </li></ol></li><li> Circa 15 minuti prima della fine dell&#39;incubazione, risospendere il 14C-palmitato in NaOH 0,1 N (12.5 ml / uCi). Incubare a 70 ° C per 10 min. Aggiungere tre volumi di caldo pre-incubazione medio e mescolare pipettando su e giù. </li><li> Spike ogni pozzetto con 25 ml di diluito 14 C-palmitato. Mescolare scuotendo delicatamente la piastra e incubare a 37 ° C per 90 min. Questa è la piastra saggio. </li><li> Durante l&#39;incubazione, preparare la piastra di filtraggio di carta (Figura 1). <ol><li> Togliere il coperchio da un 24-pozzetti sterili. Posizionare un 2 cm x 2 cm pezzo di carta da filtro sul fondo di ciascun pozzetto. Sovrapporre il piatto con un pezzo di 4 &quot;x 7&quot; parafilm. </li><li> Utilizzando un grande oggetto rettangolare, ad esempio una casella punta della micropipetta, strofinare la parafilm sui pozzetti per perforare la parafilm le aperture oltre e creare una tenuta sul resto della piastra. Rimuovere i cerchi forati di parafilm ora coprono i pozzetti. La piastra dovrebbe essere ben coperto con parafilm in tutte le zone tranne il bene openings. </li></ol></li><li> 10 min prima della fine dell&#39;incubazione, aggiungere 200 ml di NaOH N 3 a ciascun pozzetto della piastra Filter Paper, assicurandosi che la carta da filtro assorbe tutto il liquido. <ol><li> Facoltativamente prima del congelamento, trasferire il mezzo di una piastra da 24 pozzetti fresco. Dopo aver lavato una volta con PBS, la lisi dei rimanenti cellule in 0,1 N HCl e calcolare il contenuto proteico mediante test BCA. </li></ol></li><li> Al termine dell&#39;incubazione, snap-congelare la piastra di dosaggio in azoto liquido. Fare attenzione a garantire che ogni bene è completamente congelato prima di procedere. </li><li> Aggiungere 100 ml di 70% di acido perclorico in ogni pozzetto della piastra saggio. Coprire immediatamente con la piastra di carta da filtro. Posizionare le piastre su un agitatore orbitale e roccia alla velocità orbitale di 80 rpm a temperatura ambiente per 2 ore. </li><li> In seguito l&#39;incubazione, processare i campioni: <ol><li> Per misurare la frazione di CO 2, trasferire i quadrati di carta filtro a 4 ml di fluido di scintillazione liquida in un scintillazionefiala e misura 14 Segnale C. </li><li> Per misurare il materiale solubile acido, trasferire 400 ml di mezzo in una provetta da 1,5 ml microcentrifuga. Centrifugare alla massima velocità per 10 min. Aggiungere 100 pl del supernatante risultante a 500 ml di 2: 1 cloroformio-metanolo (v / v) e miscelare brevemente. <ol><li> Aggiungere 250 ml di acqua alla miscela, e di nuovo vortice. Campioni di centrifugazione per 10 min a 3000 x g. Trasferimento 200 ml di fase superiore a 4 ml di liquido di scintillazione liquido in un flaconcino scintillazione e misura 14 Segnale C. </li></ol></li></ol></li></ol> 4. Lipogenesi Assay <ol><li> La sera prima di iniziare il test, lavare le cellule 2 volte con il caldo PBS. Modificare le epatociti a Serum fame media con 100 nM insulina. Incubare una notte a 37 ° C. Nota: Poiché siero fetale bovino contiene una concentrazione sconosciuta di ormoni metabolici (per esempio insulina, glucagone), Il siero morire di fame le cellule per rimuovere eventuali effetti confondenti questa può avere sul dosaggio. Le cellule sono vitali nel siero fame medio per&gt; 24 ore. L&#39;insulina è usato in questo test per stimolare la lipogenesi. </li><li> Fai Lipogenesi Media: Siero fame medio con 100 nM insulina, 10 micron acetato freddo e 0,5 uCi 3 H-acetato per pozzetto. Modificare le celle a Lipogenesi media e incubare a 37 ° C per 2 ore. Includere eventuali composti di interesse da testare. </li><li> Dopo il periodo di incubazione, lavare le cellule 2 volte con PBS. Lisare le cellule raschiando in 120 ml di 0,1 N HCl. Riserva 10 microlitri per l&#39;analisi delle proteine ​​(valutare mediante test BCA), e il trasferimento di 100 l per provetta da 1,5 ml microcentrifuga. </li><li> Estratto lipidi per aggiunta di 500 ml di 2: 1 cloroformio-metanolo (v / v). Vortex brevemente e incubare a temperatura ambiente per 5 min. Aggiungere 250 ml di acqua, vortice e incubare a temperatura ambiente per un ulteriore 5 min. Centrifugare i campioni 10 min a 3000 x g, RT. Accuratamentetrasferire fase inferiore a 4 ml liquido di scintillazione liquido in un flaconcino scintillazione e misurare l&#39;attività 3 H. </li></ol>

<ol>
	<li>Clark, J. M., Brancati, F. L., Diehl, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+prevalence+and+etiology+of+elevated+aminotransferase+levels+in+the+United+States.">The prevalence and etiology of elevated aminotransferase levels in the United States.</a> The American journal of gastroenterology. 98, 960-967 (2003).</li><li>Lazo, 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=Prevalence+of+nonalcoholic+Fatty+liver+disease+in+the+United+States:+the+third+national+health+and+nutrition+examination+survey,+1988-1994.">Prevalence of nonalcoholic Fatty liver disease in the United States: the third national health and nutrition examination survey, 1988-1994.</a> American journal of epidemiology. 178, 38-45 (2013).</li><li>Angulo, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonalcoholic+fatty+liver+disease.">Nonalcoholic fatty liver disease.</a> The New England journal of medicine. 346, 1221-1231 (2002).</li><li>Adams, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+natural+history+of+nonalcoholic+fatty+liver+disease:+a+population-based+cohort+study.">The natural history of nonalcoholic fatty liver disease: a population-based cohort study.</a> Gastroenterology. 129, 113-121 (2005).</li><li>Feldstein, A. E., 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=Hepatocyte+apoptosis+and+fas+expression+are+prominent+features+of+human+nonalcoholic+steatohepatitis.">Hepatocyte apoptosis and fas expression are prominent features of human nonalcoholic steatohepatitis.</a> Gastroenterology. 125, 437-443 (2003).</li><li>Day, C. P., James, O. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Steatohepatitis:+a+tale+of+two+'hits'.">Steatohepatitis: a tale of two 'hits'.</a> Gastroenterology. 114, 842-845 (1998).</li><li>Donnelly, K. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sources+of+fatty+acids+stored+in+liver+and+secreted+via+lipoproteins+in+patients+with+nonalcoholic+fatty+liver+disease.">Sources of fatty acids stored in liver and secreted via lipoproteins in patients with nonalcoholic fatty liver disease.</a> The Journal of clinical investigation. 115, 1343-1351 (2005).</li><li>Lambert, J. E., Ramos-Roman, M. A., Browning, J. D., Parks, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+de+novo+lipogenesis+is+a+distinct+characteristic+of+individuals+with+nonalcoholic+fatty+liver+disease.">Increased de novo lipogenesis is a distinct characteristic of individuals with nonalcoholic fatty liver disease.</a> Gastroenterology. 146, 726-735 (2014).</li><li>Parks, E. J., Hellerstein, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thematic+review+series:+patient-oriented+research.+Recent+advances+in+liver+triacylglycerol+and+fatty+acid+metabolism+using+stable+isotope+labeling+techniques.">Thematic review series: patient-oriented research. Recent advances in liver triacylglycerol and fatty acid metabolism using stable isotope labeling techniques.</a> Journal of lipid research. 47, 1651-1660 (2006).</li><li>Befroy, D. E., 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=Direct+assessment+of+hepatic+mitochondrial+oxidative+and+anaplerotic+fluxes+in+humans+using+dynamic+13C+magnetic+resonance+spectroscopy.">Direct assessment of hepatic mitochondrial oxidative and anaplerotic fluxes in humans using dynamic 13C magnetic resonance spectroscopy.</a> Nature medicine. 20, 98-102 (2014).</li><li>Goncalves, L. A., Vigario, A. M., Penha-Goncalves, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+isolation+of+murine+hepatocytes+for+in+vitro+malaria+liver+stage+studies.">Improved isolation of murine hepatocytes for in vitro malaria liver stage studies.</a> Malaria journal. 6, 169 (2007).</li></ol>

The authors indicate they have no conflicts of interest.

Il tempo dal sacrificio perfusione deve essere inferiore a 3 minuti per perfusione ideale e collagenasi digestione del fegato. Una volta iniziata la perfusione con perfusione Media, il fegato dovrebbe cambiare immediatamente aspetto a dal rosso al pallido. Dopo circa 10 minuti di incubazione con LDM, il fegato apparirà gonfio e rosa. Nel caso in cui perfusione è insufficiente, il fegato non può presentare tali modifiche, e ciò avrà come risultato una resa minore epatociti. Dopo le fasi ...

Non-alcoholic fatty liver disease is one of the leading causes of liver disease in Westernized cultures1,2. Lipid accumulation within the liver is associated with cell death, fibrosis, and liver failure via yet unknown mechanisms3-6. In fatty liver disease, hepatocyte-mediated &#946;-fatty acid oxidation and de novo lipogenesis are important determinants of net lipid accumulation7,8. This article will, therefore, focus on hepatocyte isolation, followed by quantification of &#946;-fatty acid oxidation and de novo lipogenesis.
Numerous methodologies have been developed to interrogate hepatocyte lipid metabolism. Though it is possible to measure metabolism of fat in vivo using stable isotopes9,10, these methods are costly, and require large numbers of animals. Additionally, the ability to investigate the effect of exogenous chemicals is limited due to the nature of in vivo experimentation. In contrast, the isolation of primary hepatocytes from mouse liver provides an affordable avenue to pursue11. Furthermore, studying hepatocytes in culture allows investigators to study the effects of varying chemicals on lipid processing while circumventing the difficulties of in vivo experimentation. Finally, isolated hepatocytes avoid any confounding from varying genetics since they are derived from the liver of a single animal.
Here we isolate and culture of hepatocytes, and we measure &#946;-fatty acid oxidation and de novo lipogenesis, using radiolabeled palmitate. The protocol detailed below is straight forward, effective, and reproducible.

<table><tbody><tr><td>Liver Perfusion Medium</td><td>Life Technologies</td><td>17701038</td><td></td></tr><tr><td>Liver Digest Medium</td><td>Life Technologies</td><td>17703034</td><td>Aliquot and store at -20 &amp;deg;C</td></tr><tr><td>PBS</td><td>Corning</td><td>21-040-CV</td><td></td></tr><tr><td>10X DPBS</td><td>Corning</td><td>46-013-CM</td><td></td></tr><tr><td>DMEM</td><td>Corning</td><td>10-017-CV</td><td></td></tr><tr><td>FBS</td><td>Life Technologies</td><td>26140079&amp;nbsp;</td><td></td></tr><tr><td>Collagen</td><td>Life Technologies</td><td>A1048301&amp;nbsp;</td><td></td></tr><tr><td>Colloidal silica coated with polyvinylpyrrolidone</td><td>GE Life Sciences</td><td>17-0891-01</td><td></td></tr><tr><td>Sodium Pyruvate</td><td>Cellgro</td><td>25-000-CI</td><td></td></tr><tr><td>Penicillin / Streptomycin</td><td>Cellgro</td><td>30-001-CI</td><td></td></tr><tr><td>Insulin</td><td>Sigma</td><td>I0516-5ML</td><td></td></tr><tr><td>Dexamethasone</td><td>Sigma</td><td>D2915-100MG</td><td></td></tr><tr><td>Albumin (BSA), Fraction V</td><td>MP Biomedicals</td><td>103703</td><td></td></tr><tr><td>24-Well Culture Dish</td><td>Corning Falcon</td><td>353047&amp;nbsp;</td><td></td></tr><tr><td>Tygon S3 Tubing&amp;nbsp;</td><td>Cole Parmer</td><td>06460-34</td><td></td></tr><tr><td>Male Leur Lock to 200 Barb Connectors</td><td>Cole Parmer</td><td>45518-00</td><td></td></tr><tr><td>24 G x 3/4&quot; Catheter</td><td>SurFlo</td><td>SROX2419CA</td><td></td></tr><tr><td>Perma-Hand Silk Suture</td><td>Ethicon</td><td>683G</td><td></td></tr><tr><td>Cell Strainer</td><td>Corning Falcon</td><td>08-771-2</td><td></td></tr><tr><td>IsoTemp 3013HD Recirculating Water Bath</td><td>Fisher</td><td>13-874-3</td><td></td></tr><tr><td>MasterFlex C/L Peristaltic Pump</td><td>MasterFlex</td><td>HV-77122-24</td><td></td></tr><tr><td>Microclamp</td><td>Roboz</td><td>RS-7438</td><td>Pre-sterilize in autoclave</td></tr><tr><td>5&amp;rdquo; Straight, Blunt-Blunt Operating Scissors</td><td>Roboz</td><td>RS-6810</td><td>Pre-sterilize in autoclave</td></tr><tr><td>24 mm Blade Straight, Sharp-point Microdissecting Scissors</td><td>Roboz</td><td>RS-5912</td><td>Pre-sterilize in autoclave</td></tr><tr><td>4&amp;rdquo; 0.8 mm Tip Microdissecting Forceps</td><td>Roboz</td><td>RS-5130</td><td>Pre-sterilize in autoclave</td></tr><tr><td>4&amp;rdquo; 0.8 mm Tip Full Curve Microdissecting Forceps</td><td>Roboz</td><td>RS-5137</td><td>Pre-sterilize in autoclave</td></tr><tr><td>60 ml Syringe</td><td>Becton Dickinson</td><td>309653</td><td></td></tr><tr><td>50 ml conical tubes</td><td>Corning Falcon</td><td>352070</td><td></td></tr><tr><td>BCA Protein Assay</td><td>Thermo Scientific</td><td>23225</td><td></td></tr><tr><td>Biosafety Cabinet</td><td></td><td></td><td></td></tr><tr><td>CO&lt;sub&gt;2 &lt;/sub&gt;Incubator</td><td></td><td></td><td></td></tr><tr><td>Serological pipets</td><td></td><td></td><td></td></tr><tr><td>1,000, 200, 20 &amp;mu;l pipet and tips</td><td></td><td></td><td></td></tr></tbody></table>

determination of fatty acid oxidation and lipogenesis in mouse primary hepatocytes

Lipid metabolism in liver is complex. In addition to importing and exporting lipid via lipoproteins, hepatocytes can oxidize lipid via fatty acid oxidation, or alternatively, synthesize new lipid via de novo lipogenesis. The net sum of these pathways is dictated by a number of factors, which in certain disease states leads to fatty liver disease. Excess hepatic lipid accumulation is associated with whole body insulin resistance and coronary heart disease. Tools to study lipid metabolism in hepatocytes are useful to understand the role of hepatic lipid metabolism in certain metabolic disorders.
In the liver, hepatocytes regulate the breakdown and synthesis of fatty acids via &#946;-fatty oxidation and de novo lipogenesis, respectively. Quantifying metabolism in these pathways provides insight into hepatic lipid handling. Unlike in vitro quantification, using primary hepatocytes, making measurements in vivo is technically challenging and resource intensive. Hence, quantifying &#946;-fatty acid oxidation and de novo lipogenesis in cultured mouse hepatocytes provides a straight forward method to assess hepatocyte lipid handling. 
Here we describe a method for the isolation of primary mouse hepatocytes, and we demonstrate quantification of &#946;-fatty acid oxidation and de novo lipogenesis, using radiolabeled substrates.

Isolamenti epatociti tipicamente risultato in 1 - 3 x 10 7 cellule totali. Dopo incubazione per una notte, le cellule appariranno esagonale, molti dei quali saranno binucleate (Figura 2). Le cellule sane dovrebbero essere privi di granulazioni o vesciche, indicativi della morte cellulare. In generale, dosaggio di acidi grassi ossidazione viene eseguito in tre o quattro repliche per composto in esame. Conti per le CO 2 campioni sono circa un quinto di qu...

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Determination of Fatty Acid Oxidation and Lipogenesis in Mouse Primary Hepatocytes

De novo lipogenesi e acido ossidazione β-grassi costituiscono importanti vie metaboliche in epatociti, percorsi che sono perturbate in diversi disordini metabolici, tra cui malattia del fegato grasso. Qui mostriamo isolamento di epatociti primari di topo e descriviamo la quantificazione di ossidazione degli acidi β-grassi e lipogenesi.

Determinazione della ossidazione degli acidi grassi e la lipogenesi nel topo primaria Epatociti

Lipid metabolism in liver is complex. In addition to importing and exporting lipid via lipoproteins, hepatocytes can oxidize lipid via fatty acid ...

determination-fatty-acid-oxidation-lipogenesis-mouse-primary

Research

JoVE Journal

Biology

20.1K Views.  University of Massachusetts Medical School.  De novo lipogenesi e acido ossidazione β-grassi costituiscono importanti vie metaboliche in epatociti, percorsi che sono perturbate in diversi disordini metabolici, tra cui malattia del fegato grasso. Qui mostriamo isolamento di epatociti primari di topo e descriviamo la quantificazione di ossidazione degli acidi β-grassi e lipogenesi. 

Video: Determination of Fatty Acid Oxidation and Lipogenesis in Mouse Primary Hepatocytes

Measurement of Fatty Acid &#946;-Oxidation in a Suspension of Freshly Isolated Mouse Hepatocytes

Fatty acid &#946;-oxidation is a key metabolic pathway to meet the energy demands of the liver and provide substrates and cofactors for additional processes, such as ketogenesis and gluconeogenesis, which are essential to maintain whole-body glucose homeostasis and support extra-hepatic organ function in the fasted state. Fatty acid &#946;-oxidation occurs within the mitochondria and peroxisomes and is regulated through multiple mechanisms, including the uptake and activation of fatty acids, enzyme expression levels, and availability of cofactors such as coenzyme A and NAD+. In assays that measure fatty acid &#946;-oxidation in liver homogenates, cell lysis and the common addition of supraphysiological levels of cofactors mask the effects of these regulatory mechanisms. Furthermore, the integrity of the organelles in the homogenates is hard to control and can vary significantly between preparations. The measurement of fatty acid &#946;-oxidation in intact primary hepatocytes overcomes the above pitfalls. This protocol describes a method for the measurement of fatty acid &#946;-oxidation in a suspension of freshly isolated primary mouse hepatocytes incubated with 14C-labeled palmitic acid. By avoiding hours to days of culture, this method has the advantage of better preserving the protein expression levels and metabolic pathway activity of the original liver, including the activation of fatty acid &#946;-oxidation observed in hepatocytes isolated from fasted mice compared to fed mice.

Fatty acid &#946;-oxidation is an essential metabolic pathway responsible for generating energy in many different cell types, including hepatocytes. Here, we describe a method to measure fatty acid &#946;-oxidation in freshly isolated primary hepatocytes using 14C-labeled palmitic acid.

Misurazione della β-ossidazione degli acidi grassi in una sospensione di epatociti di topo appena isolati

Fatty acid &#946;-oxidation is a key metabolic pathway to meet the energy demands of the liver and provide substrates and cofactors for additional ...

Ricerca

Biochimica

Optimized Analysis of In Vivo and In Vitro Hepatic Steatosis

Establishing a system of procedures to qualitatively and quantitatively characterize in vivo and in vitro hepatic steatosis is important for metabolic study in the liver. Here, numerous assays are described to comprehensively measure the phenotype and parameters of hepatic steatosis in mouse and hepatocyte models. 
Combining the physiological, histological, and biochemical methods, this system can be used to assess the progress of hepatic steatosis. In vivo, the measurements of body weight and nuclear magnetic resonance (NMR) provide a general understanding of mice in a non-invasive manner. Hematoxylin and Eosin (H&amp;E) and Oil Red O staining determine the histological morphology and lipid deposition of liver tissue under nutrient overload conditions, such as high-fat diet feeding. Next, the total lipid contents are isolated by chloroform/methanol extraction, which are followed by a biochemical analysis for triglyceride and cholesterol. Moreover, mouse primary hepatocytes are treated with high glucose plus insulin to stimulate lipid accumulation, an efficient in vitro model to mimic diet-induced hyperglycemia and hyperinsulinemia in vivo. Then, the lipid deposition is measured by Oil Red O staining and chloroform/methanol extraction. Oil Red O staining determines intuitive hepatic steatotic phenotypes, while the lipid extraction analysis determines the parameters that can be analyzed statistically. The present protocols are of interest to scientists in the fields of fatty liver diseases, insulin resistance, and type 2 diabetes.

Optimized Analysis of In Vivo and In Vitro Hepatic Steatosis

Here, optimized methods to generate in vivo and in vitro models of hepatic steatosis and to analyze the steatotic phenotypes and related physiological parameters are described.

Analisi ottimizzata delle<em&gt; In Vivo</em&gt; e<em&gt; In Vitro</em&gt; Epatica steatosi

Establishing a system of procedures to qualitatively and quantitatively characterize in vivo and in vitro hepatic steatosis is important for metabolic ...

Medicina

Isolation of Primary Mouse Hepatocytes for Nascent Protein Synthesis Analysis by Non-radioactive L-azidohomoalanine Labeling Method

Hepatocytes are parenchymal cells of the liver and engage multiple metabolic functions, including synthesis and secretion of proteins essential for systemic energy homeostasis. Primary hepatocytes isolated from the murine liver constitute a valuable biological tool to understand the functional properties or alterations occurring in the liver. Herein we describe a method for the isolation and culture of primary mouse hepatocytes by performing a two-step collagenase perfusion technique and discuss their utilization for investigating protein metabolism. The liver of an adult mouse is sequentially perfused with ethylene glycol-bis tetraacetic acid (EGTA) and collagenase, followed by the isolation of hepatocytes with the density gradient buffer. These isolated hepatocytes are viable on culture plates and maintain the majority of endowed characteristics of hepatocytes. These hepatocytes can be used for assessments of protein metabolism including nascent protein synthesis with non-radioactive reagents. We show that the isolated hepatocytes are readily controlled and comprise a higher quality and volume stability of protein synthesis linked to energy metabolism by utilizing the chemo-selective ligation reaction with a Tetramethylrhodamine (TAMRA) protein detection method and western blotting analyses. Therefore, this method is valuable for investigating hepatic nascent protein synthesis linked to energy homeostasis. The following protocol outlines the materials and methods for the isolation of high-quality primary mouse hepatocytes and detection of nascent protein synthesis.

Here, we present a protocol for the isolation of healthy and functional primary mouse hepatocytes. Instructions for detecting hepatic nascent protein synthesis by non-radioactive labeling substrate were provided to help understand the mechanisms underlying protein synthesis in the context of energy-metabolism homeostasis in the liver.

Isolamento degli epatociti primari del topo per l'analisi di sintesi della proteina nascente dal metodo di etichettatura Non radioattivo L-azidohomoalanine

Hepatocytes are parenchymal cells of the liver and engage multiple metabolic functions, including synthesis and secretion of proteins essential for ...

Inducing and Characterizing Vesicular Steatosis in Differentiated HepaRG Cells

Hepatic steatosis represents a metabolic dysfunction that results from an accumulation of triglyceride-containing lipid droplets in hepatocytes. Excessive fat accumulation leads to non-alcoholic fatty liver disease (NAFLD), &#160;which is potentially reversible and may evolve into non-alcoholic steatohepatitis (NASH) and eventually cirrhosis and hepatocellular carcinoma (HCC). The molecular mechanisms linking lipid accumulation in hepatocytes with the progression to NASH, irreversible liver damage, fibrosis, cirrhosis, and even HCC still remains unclear. To this end, several in vitro and in vivo models have been developed to elucidate the pathological processes that cause NAFLD. In the present study, we describe a cellular model for the induction of liver vesicular steatosis that consists of DMSO-differentiated human hepatic HepaRG cells treated with the fatty acid salt sodium oleate. Indeed, sodium oleate-treated HepaRG cells accumulate lipid droplets in the cytoplasm and show typical features of steatosis. This in vitro human model represents a valuable alternative to in vivo mice models as well as to the primary human hepatocytes. We also present a comparison of several methods for the quantification and evaluation of fat accumulation in HepaRG cells, including Oil Red O staining, cytofluorimetric Bodipy measurement, metabolic gene expression analysis by qPCR, and coherent anti-Stokes Raman scattering (CARS) microscopy. CARS imaging combines the chemical specificity of Raman spectroscopy, a chemical analysis technique well-known in materials science applications, with the benefits of high-speed, high-resolution non-linear optical microscopies to allow precise quantification of lipid accumulation and lipid droplet dynamics. The establishment of an efficient in vitro model for the induction of vesicular steatosis, alongside an accurate method for the quantification and characterization of lipid accumulation, could lead to the development of early stage diagnosis of NAFLD via the identification of molecular markers, and to the generation of new treatment strategies.

In this study, we describe a detailed protocol for inducing liver vesicular steatosis in differentiated HepaRG cells with the fatty acid salt sodium oleate and employ methods for detection and quantification of lipid accumulation, including coherent anti-Stokes Raman scattering (CARS) microscopy, cytofluorimetric analysis, Oil red O staining, and qPCR.&#160;

Indurre e caratterizzare la vesapica steatosi nelle celle HepaRG differenziate

Hepatic steatosis represents a metabolic dysfunction that results from an accumulation of triglyceride-containing lipid droplets in hepatocytes. Excessive ...

Assessing Whole-Body Lipid-Handling Capacity in Mice

Assessing lipid metabolism is a cornerstone of evaluating metabolic function, and it is considered essential for in vivo metabolism studies. Lipids are a class of many different molecules with many pathways involved in their synthesis and metabolism. A starting point for evaluating lipid hemostasis for nutrition and obesity research is needed. This paper describes three easy and accessible methods that require little expertise or practice to master, and that can be adapted by most labs to screen for lipid-metabolism abnormalities in mice. These methods are (1) measuring several fasting serum lipid molecules using commercial kits (2) assaying for dietary lipid-handling capability through an oral intralipid tolerance test, and (3) evaluating the response to a pharmaceutical compound, CL 316,243, in mice. Together, these methods will provide a high-level overview of lipid handling capability in mice.

This paper provides three easy and accessible assays for assessing lipid metabolism in mice.

Valutazione della capacità di manipolazione dei lipidi di tutto il corpo nei topi

Assessing lipid metabolism is a cornerstone of evaluating metabolic function, and it is considered essential for in vivo metabolism studies. Lipids are a ...

A Model of Experimental Steatosis In Vitro: Hepatocyte Cell Culture in Lipid Overload-Conditioned Medium

Metabolic dysfunction-associated fatty liver disease (MAFLD), previously known as non-alcoholic fatty liver disease (NAFLD), is the most prevalent liver disease worldwide due to its relationship with obesity, diabetes type 2, and dyslipidemia. Hepatic steatosis, the accumulation of lipid droplets in the liver parenchyma, is a key feature of the disease preceding the inflammation observed in steatohepatitis, fibrosis, and end-stage liver disease. Lipid accumulation in hepatocytes might interfere with proper metabolism of xenobiotics and endogenous molecules, as well as to induce cellular processes leading to the advance of the disease. Although the experimental study of steatosis can be performed in vivo, in vitro approaches to the study of steatosis are complementary tools with different advantages. Hepatocyte culture in lipid overload-conditioned medium is an excellent reproducible option for the study of hepatic steatosis allowing the identification of cellular processes related to lipid accumulation, such as oxidative and reticular stresses, autophagia, proliferation, cell death, etcetera, as well as other testing including drug effectiveness, and toxicological testing, among many other possible applications. Here, it was aimed to describe the methodology of hepatocyte cell culture in lipid overload-conditioned medium. HepG2 cells were cultured in RMPI 1640 medium conditioned with sodium palmitate and sodium oleate. Importantly, the ratio of these two lipids is crucial to favor lipid droplet accumulation, while maintaining cell proliferation and a moderate mortality rate, as occurs in the liver during the disease. The methodology, from the preparation of the lipid solution stocks, mixture, addition to the medium, and hepatocyte culture is shown. With this approach, it is possible to identify lipid droplets in the hepatocytes that are readily observable by Oil-red O staining, as well as curves of proliferation/mortality rates.

A Model of Experimental Steatosis In Vitro: Hepatocyte Cell Culture in Lipid Overload-Conditioned Medium

This protocol is intended to be a tool to study steatosis and the molecular, biochemical, cellular changes produced by the over exposure of hepatocytes to lipids in vitro.

Un modello di steatosi sperimentale in vitro:coltura cellulare di epatociti in mezzo condizionato da sovraccarico lipidico

Metabolic dysfunction-associated fatty liver disease (MAFLD), previously known as non-alcoholic fatty liver disease (NAFLD), is the most prevalent liver ...

An Improved Time- and Labor- Efficient Protocol for Mouse Primary Hepatocyte Isolation

Primary hepatocytes are used extensively in liver in vitro research, especially in glucose metabolism studies. A base technique has been adapted based on different needs, like time, labor, cost, and primary hepatocyte usage, resulting in various primary hepatocyte isolation protocols. However, the numerous steps and time-consuming reagent preparations in primary hepatocyte isolation are major drawbacks for efficiency. After comparing different protocols for their pros and cons, the advantages of each were combined, and a rapid and efficient primary hepatocyte isolation protocol was formulated. Within only ~35 min, this protocol could yield as much, if not more, healthy primary hepatocytes as other protocols. Further, glucose metabolism experiments performed using the isolated primary hepatocytes validated the usefulness of this protocol in in vitro liver metabolism studies. We also extensively reviewed and analyzed the significance and purpose of each step in this study so that future researchers can further optimize this protocol based on needs.

Primary hepatocytes are a valuable tool to study liver response and metabolism in vitro. Utilizing commercially available reagents, an improved time- and labor-efficient protocol for mouse primary hepatocyte isolation was developed.

Un protocollo migliorato efficiente in termini di tempo e fatica per l'isolamento degli epatociti primari del topo

Primary hepatocytes are used extensively in liver in vitro research, especially in glucose metabolism studies. A base technique has been adapted based on ...

Biologia

Evaluation of Fatty Acid Oxidation in Cultured Bone Cells

Bone formation by differentiating osteoblasts is expected to require significant energetic input as these specialized cells must synthesize large extracellular matrix proteins that compose bone tissue and then concentrate the ions necessary for its mineralization. Data on the metabolic requirements of bone formation are emerging rapidly. While much remains to be learned, it is expected that derangements in the intermediary metabolism contribute to skeletal disease. Here, a protocol is outlined to assess the capacity of osteoblastic cells to oxidize 14C-labeled fatty acids to 14CO2 and acid-soluble metabolites. Fatty acids represent a rich-energy reserve that can be taken up from the circulation after feeding or after their liberation from adipose tissue stores. The assay, performed in T-25 tissue culture flasks, is helpful for the study of gene gain or loss-of-function on fatty acid utilization and the effect of anabolic signals in the form of growth factors or morphogens necessary for the maintenance of bone mass. Details on the ability to adapt the protocol to assess the oxidation of glucose or amino acids like glutamine are also provided.

The present protocol describes an assay to assess the capacity for fatty acid oxidation in cultures of primary bone cells or relevant cell lines.

Bone formation by differentiating osteoblasts is expected to require significant energetic input as these specialized cells must synthesize large ...

Measuring the Rate of Lipolysis in Ex Vivo Murine Adipose Tissue and Primary Preadipocytes Differentiated In Vitro

Adipocytes store energy in the form of triglycerides in lipid droplets. This energy can be mobilized via lipolysis, where the fatty acid side chains are sequentially cleaved from the glycerol backbone, resulting in the release of free fatty acids and glycerol. Due to the low expression of glycerol kinase in white adipocytes, glycerol re-uptake rates are negligible, while fatty acid re-uptake is dictated by the fatty acid binding capacity of media components such as albumin. Both glycerol and fatty acid release into media can be quantified by colorimetric assays to determine the lipolytic rate. By measuring these factors at multiple time points, one can determine the linear rate of lipolysis with high confidence. Here, we provide a detailed protocol for the measurement of lipolysis in in vitro differentiated adipocytes and ex vivo adipose tissue from mice. This protocol may also be optimized for other preadipocyte cell lines or adipose tissue from other organisms; considerations and optimization parameters are discussed. This protocol is designed to be useful in determining and comparing the rate of adipocyte lipolysis between mouse models and treatments.

Measuring the Rate of Lipolysis in Ex Vivo Murine Adipose Tissue and Primary Preadipocytes Differentiated In Vitro

Triglyceride lipolysis in adipocytes is an important metabolic process resulting in the liberation of free fatty acids and glycerol. Here, we provide a detailed protocol to measure basal and stimulated lipolysis in adipocytes and ex vivo adipose tissue from mice.

Misurazione del tasso di lipolisi nel tessuto adiposo murino ex vivo e nei preadipociti primari differenziati in vitro

Adipocytes store energy in the form of triglycerides in lipid droplets. This energy can be mobilized via lipolysis, where the fatty acid side chains are ...

Isolamento semi-automatico del tessuto adiposo bianco murino

Semi-Automated Isolation of the Stromal Vascular Fraction from Murine White Adipose Tissue Using a Tissue Dissociator

The in vitro study of white, brown, and beige adipocyte differentiation enables the investigation of cell-autonomous functions of adipocytes and their mechanisms. Immortalized white preadipocyte cell lines are publicly available and widely used. However, the emergence of beige adipocytes in white adipose tissue in response to external cues is difficult to recapitulate to the full extent using publicly available white adipocyte cell lines. Isolation of the stromal vascular fraction (SVF) from murine adipose tissue is commonly executed to obtain primary preadipocytes and perform adipocyte differentiation. However, mincing and collagenase digestion of adipose tissue by hand can result in experimental variation and is prone to contamination. Here, we present a modified semi-automated protocol that utilizes a tissue dissociator for collagenase digestion to achieve easier isolation of the SVF, with the aim of reducing experimental variation, reducing contamination, and increasing reproducibility. The obtained preadipocytes and differentiated adipocytes can be used for functional and mechanistic analyses.

Autore in primo piano: Isolamento semi-automatico della frazione vascolare stromale dal tessuto adiposo bianco murino utilizzando un dissociatore tissutale  

This protocol describes the semi-automated isolation of the stromal vascular fraction (SVF) from murine adipose tissue to obtain preadipocytes and achieve adipocyte differentiation in vitro. Using a tissue dissociator for collagenase digestion reduces experimental variation and increases reproducibility.

Isolamento semi-automatico della frazione vascolare stromale dal tessuto adiposo bianco murino mediante un dissociatore tissutale

The in vitro study of white, brown, and beige adipocyte differentiation enables the investigation of cell-autonomous functions of adipocytes and their ...