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).

All animal experimentation should be carried out in accordance with local and federal regulations and with the approval of an institutional IACUC and radiation safety administration.
1. Preparation
<ol>
	<li>Several days prior to the assay, thaw the 500 ml&#160;bottle of Liver Digest Medium (LDM) and refreeze ~35 ml&#160;aliquots in 50 ml&#160;conical tubes. Store at -20 &#176;C until needed.</li>
	<li>One day prior to the assay, pre-sterilize clean dissection tools by autoclave.</li>
	<li>On the day of the assay, treat the necessary amount of 24-well culture plates with collagen.
	<ol>
		<li>Mix 1 part of 3 mg/ml&#160;rat tail collagen with 50 parts of PBS. Add approximately 500 &#181;l&#160;to each well of a 24-well plate and incubate for 3-5 min at room temperature (RT). Remove the collagen and allow plate to air dry in hood. Repeat at least one additional time. 
		Note: Collagen coating can be performed up to one week in advance and plates stored at 4 &#176;C sealed in plastic wrap.</li>
	</ol>
	</li>
	<li>Prepare LDM for assay: Thaw LDM and warm to 37 &#176;C and adjust pH to 7.4 using 1 N KOH. Filter using 0.2 &#181;m syringe filter and place in a recirculating 42 &#176;C water bath.</li>
	<li>Warm 25 ml&#160;of Liver Perfusion Medium to 42 &#176;C in recirculating water bath.</li>
	<li>Prepare 90% colloidal silica coated with polyvinylpyrrolidone solution: Add 1 ml&#160;of 10x DPBS to 9 ml&#160;of colloidal silica coated with polyvinylpyrrolidone. Adjust pH to 7.4 using 0.1 N HCl. Filter with a sterile 0.2 &#181;m syringe filter. Store at RT.</li>
	<li>Warm Plating Medium to 37 &#176;C.</li>
</ol>
2. Isolation of Primary Mouse Hepatocytes
<ol>
	<li>Set up peristaltic pump, tubing, and dissection table: Sterilize tubing by flushing with 5 ml&#160;70% ethanol in distilled water, followed by 10 ml&#160;of sterile water. Place tubing in Liver Perfusion Medium and run pump to fill entire length of tubing.</li>
	<li>Sacrifice mouse by the institutionally approved method.</li>
	<li>Dissect open the abdominal cavity: Spray the mouse abdomen liberally with 70% ethanol. Using blunt-end scissors, make a midline incision through the dermis the length of the abdomen and reflect laterally. Make a similar incision in the peritoneum to expose the viscera.
	<ol>
		<li>Using a blunt instrument, gently displace the intestines to expose the abdominal vasculature Locate the abdominal inferior vena cava (IVC) and place a suture underneath the blood vessel, distal to the renal vein</li>
	</ol>
	</li>
	<li>Distal to the suture, place a needle and catheter into the IVC, advancing it beyond the level of the suture. With the needle still in place, tie the suture around the catheter to hold it in place. Carefully remove the needle. If done correctly, blood with flow through the catheter.</li>
	<li>Using a pipet, fill the remaining area in the catheter with perfusion medium, ensuring that no air is present. With great care, attach the tubing to the catheter.</li>
	<li>Dissect open the lung cavity: gently reflect the superior liver lobes to expose the diaphragm. Carefully puncture the diaphragm with sharp tip scissors, then make a lateral incision to expose the pleural cavity, taking care to avoid the gall bladder and pleural vasculature. Place a bulldog clamp around the thoracic inferior vena cava just proximal to the hepatic vein.</li>
	<li>Cut the portal vein and turn on the pump at 3 - 4 ml/min. Perfuse the liver with Liver Perfusion Medium for 5 min using approximately 20 ml&#160;of perfusion medium. 
	Note: The liver should immediately change from red to grey/tan. If portions of the liver remain red, this likely indicates poor perfusion, and the likelihood of successful isolation is greatly diminished. During the perfusion, be careful to ensure the medium does not run out and that no bubbles enter the tubing.</li>
	<li>Following the 5 min incubation, stop the pump and transfer the tubing to Liver Digest Medium. Restart the pump and perfuse the liver for another 10 - 15 min (until the medium is exhausted).</li>
	<li>At the end of the perfusion, stop the pump. The liver should have a pinkish hue and appear somewhat enlarged. Excise the liver by careful dissection. Remove the gall bladder and transfer the liver to 10 cm tissue culture dish.</li>
	<li>In a biosafety cabinet, add 10 ml&#160;of Plating Medium ( Table 1) to the liver. Gently scrape the liver using either forceps or a scalpel to remove the hepatocytes. Filter the suspension using a 100 &#181;m cell strainer and transfer to a 50 ml&#160;conical tube. Wash the plate with an additional 10 ml&#160;of Plating Medium and pool in the 50 ml&#160;conical tube.</li>
	<li>Pellet the cells by centrifuging for 5 min at 350 x g, 4 &#176;C.</li>
	<li>Aspirate medium and resuspend pellet in 10 ml&#160;of Plating Medium and add 10 ml&#160;of 90% colloidal silica coated with polyvinylpyrrolidone. Mix gently and centrifuge as in step 2.11. After centrifugation, a layer of dead cells will be floating on the top of the mixture, while the live cells will pellet to the bottom.</li>
	<li>Aspirate dead cells and medium. Wash 2 times with 20 ml&#160;of Plating Medium, centrifuge as in 2.11.</li>
	<li>Resuspend cells in 10 ml&#160;of Plating Medium. Count cells with a hemocytometer and place 9 x 104 cells/well in collagen-treated 24-well culture dishes. Incubate in a 37 &#176;C tissue culture incubator for 2 hr. Each plate can be used for either the Fatty Acid Oxidation assay OR the Lipogenesis assay.</li>
	<li>Optionally, change wells to Maintenance Medium (Table 1) and culture at 37 &#176;C. Cells can be cultured for 2 - 3 days without affecting assay results.</li>
</ol>
3. Fatty Acid Oxidation Assay
Warning: Use of radioactivity can be hazardous. All purchasing, storage, handling, and disposal of radioactive material should be carried out in accordance with institutional, state, and federal regulations and guidelines.
<ol>
	<li>16 - 20 hr prior to assay, wash cells 2 times with warm PBS. Change the cells to serum-free Serum Starvation Medium (Table 1) with 20 nM glucagon and incubate overnight at 37 &#176;C. 
	Note: Because fetal bovine serum contains an unknown concentration of metabolic hormones (e.g. insulin, glucagon), serum starve the cells to remove any confounding effects this may have on the assay. Cells are viable in Serum Starvation Medium for &#62;24 hr. Glucagon treatment is used to stimulate fatty acid oxidation within the hepatocytes.</li>
	<li>On the morning of the assay, prepare Pre-Incubation Medium: Resuspend an appropriate amount of Sodium Palmitate in ultrapure water to make a 100 mM solution and heat to 70 &#176;C for 10 min. In the meantime, prepare the requisite amount (0.5 ml&#160;per well of a 24-well plate) of DMEM with 25 mM HEPES, 1% BSA Fraction V, and 20 nM glucagon. Heat to 37 &#176;C.
	<ol>
		<li>Once solubilized, add Palmitate to a final concentration of 250 &#181;M to the medium. Change hepatocytes to Pre-Incubation Medium and incubate at 37 &#176;C for 2 hr. Reserve some Pre-Incubation Medium at 37 &#176;C for later use.</li>
	</ol>
	</li>
	<li>During the incubation, dry an appropriate amount of 14C-Palmitate (0.5 &#181;Ci/well) by evaporation under nitrogen gas.
	<ol>
		<li>For example, to measure 24 samples in a 24-well plate, transfer 120 &#181;l&#160;of 0.1 &#181;Ci/ml14 C-Palmitate to a 1.5 ml&#160;tube. Slowly evaporate the ethanol solvent by blowing nitrogen gas over the solution from a distance of 3-5 cm in a fume hood. The solvent should evaporate in approximately 30 - 40 min, leaving dry 14C-Palmitate in the bottom of the tube.</li>
	</ol>
	</li>
	<li>Approximately 15 min&#160;before the end of the incubation, resuspend the 14C-Palmitate in 0.1 N NaOH (12.5 &#181;l/&#181;Ci). Incubate at 70 &#176;C for 10 min. Add three volumes of warm Pre-Incubation Medium and mix by pipetting up and down.</li>
	<li>Spike each well with 25 &#181;l&#160;of diluted 14C-Palmitate. Mix by gently rocking the plate and incubate at 37 &#176;C for 90 min. This is the Assay Plate.</li>
	<li>During the incubation, prepare the Filter Paper Plate (Figure 1).
	<ol>
		<li>Remove the cover from a sterile 24-well plate. Place one 2 cm x 2 cm piece of filter paper in the bottom of each of the wells. Overlay the plate with a piece of 4&#8221; x 7&#8221; parafilm.</li>
		<li>Using a large rectangular object, such as a micropipettor tip box, rub the parafilm on the wells to perforate the parafilm at the well openings and create a seal over the remainder of the plate. Remove the perforated circles of parafilm now covering the wells. The plate should now be tightly covered with parafilm in all areas except the well openings.</li>
	</ol>
	</li>
	<li>10 min before the end of the incubation, add 200 &#181;l&#160;of 3 N NaOH to each well of the Filter Paper Plate, making sure the filter paper absorbs all of the liquid.
	<ol>
		<li>Optionally prior to freezing, transfer the medium to a fresh 24-well plate. After washing once with PBS, lyse the remaining cells in 0.1 N HCl and calculate protein content by BCA assay.</li>
	</ol>
	</li>
	<li>At the end of the incubation, snap-freeze the Assay Plate in liquid nitrogen. Be careful to ensure each well is completely frozen before proceeding.</li>
	<li>Add 100 &#181;l&#160;of 70% Perchloric Acid to each well of the Assay Plate. Immediately cover with the Filter Paper Plate. Place the plates on an orbital shaker and rock at orbital speed of 80 rpm at RT for 2 hr.</li>
	<li>Following the incubation, process the samples:
	<ol>
		<li>To measure the CO2 fraction, transfer the filter paper squares to 4 ml&#160;liquid scintillation fluid in a scintillation vial and measure 14C signal.</li>
		<li>To measure the acid soluble material, transfer 400 &#181;l&#160;of medium to a 1.5 ml&#160;microfuge tube. Centrifuge at maximum speed for 10 min. Add 100 &#181;l&#160;of the resulting supernatant to 500 &#181;l&#160;of 2:1 Chloroform-Methanol (v/v), and vortex briefly.
		<ol>
			<li>Add 250 &#181;l&#160;of water to the mixture, and vortex again. Centrifuge samples for 10 min at 3,000 x g. Transfer 200 &#181;l&#160;of the upper phase to 4 ml&#160;liquid scintillation fluid in a scintillation vial and measure 14C signal.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
4. Lipogenesis Assay
<ol>
	<li>The evening prior to beginning the assay, wash the cells 2 times with warm PBS. Change the hepatocytes to Serum Starvation Medium with 100 nM insulin. Incubate overnight at 37 &#176;C. 
	Note: Because fetal bovine serum contains an unknown concentration of metabolic hormones (e.g. insulin, glucagon), serum starve the cells to remove any confounding effects this may have on the assay. Cells are viable in Serum Starvation Medium for &#62;24 hr. Insulin is used in this assay to stimulate lipogenesis.</li>
	<li>Make Lipogenesis Medium: Serum Starvation Medium with 100 nM insulin, 10 &#181;M cold acetate and 0.5 &#181;Ci 3H-Acetate per well. Change cells to Lipogenesis Medium and incubate at 37 &#176;C for 2 hr. Include any compounds of interest to be tested.</li>
	<li>After the incubation period, wash cells 2 times with PBS. Lyse cells by scraping in 120 &#181;l&#160;of 0.1 N HCl. Reserve 10 &#181;l&#160;for protein assay (assess by BCA assay), and transfer 100 &#181;l&#160;to 1.5 ml&#160;microfuge tube.</li>
	<li>Extract lipids by addition of 500 &#181;l&#160;of 2:1 chloroform-methanol (v/v). Vortex briefly and incubate at RT for 5 min. Add 250 &#181;l&#160;of water, vortex and incubate at RT for an additional 5 min. Centrifuge samples 10 min at 3,000 x g, RT. Carefully transfer lower phase to 4 ml&#160;liquid scintillation fluid in a scintillation vial and measure 3H activity.</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.

The time from sacrifice to perfusion should be less than 3 min for ideal perfusion and collagenase digestion of the liver. Once perfusion with Perfusion Medium is initiated, the liver should immediately change appearance to from red to pale. After approximately 10 min of incubation with LDM, the liver will appear swollen and pink. In the event that perfusion is insufficient, the liver may not exhibit these changes, and this will typically result in a lower hepatocyte yield.
Following the washi...

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 border="0" cellpadding="0" cellspacing="0">
	<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 &#176;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&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagen</td>
			<td>Life Technologies</td>
			<td>A1048301&#160;</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&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Tygon S3 Tubing&#160;</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>24G x 3/4&#34; 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&#8221; Straight, Blunt-Blunt Operating Scissors</td>
			<td>Roboz</td>
			<td>RS-6810</td>
			<td>Pre-sterilize in autoclave</td>
		</tr>
		<tr>
			<td>24mm Blade Straight, Sharp-point Microdissecting Scissors</td>
			<td>Roboz</td>
			<td>RS-5912</td>
			<td>Pre-sterilize in autoclave</td>
		</tr>
		<tr>
			<td>4&#8221; 0.8mm Tip Microdissecting Forceps</td>
			<td>Roboz</td>
			<td>RS-5130</td>
			<td>Pre-sterilize in autoclave</td>
		</tr>
		<tr>
			<td>4&#8221; 0.8mm 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>CO2 Incubator</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipets</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1000, 200, 20 &#956;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.

Hepatocyte isolations typically result in 1 - 3 x 107 total cells. After overnight incubation, the cells will appear hexagonal, many of which will be binucleated (Figure 2). Healthy cells should be devoid of granulations or blebs, which are indicative of cell death.
In general, Fatty Acid Oxidation assay is run in three to four replicates per test compound. Counts for the CO2 samples are approximately one-fifth of those derived from the acid soluble mater...

Watch this Scientific Journal Video about Determination of Fatty Acid Oxidation and Lipogenesis in Mouse Primary Hepatocytes at JoVE.com

Determination of Fatty Acid Oxidation and Lipogenesis in Mouse Primary Hepatocytes

De novo lipogenesis and &#946;-fatty acid oxidation constitute key metabolic pathways in hepatocyte, pathways that are perturbed in several metabolic disorders, including fatty liver disease. Here we demonstrate isolation of mouse primary hepatocytes and describe quantification of &#946;-fatty acid oxidation and lipogenesis.

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

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JoVE Journal

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20.1K Views.  University of Massachusetts Medical School. De novo lipogenesis and β-fatty acid oxidation constitute key metabolic pathways in hepatocyte, pathways that are perturbed in several metabolic disorders, including fatty liver disease. Here we demonstrate isolation of mouse primary hepatocytes and describe quantification of β-fatty acid oxidation and lipogenesis.

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

Quantitative Phosphoproteomics in Fatty Acid Stimulated Saccharomyces cerevisiae

This protocol describes the growth and stimulation, with the fatty acid oleate, of isotopically heavy and light S. cerevisiae cells. Cells are ground using a cryolysis procedure in a ball mill grinder and the resulting grindate brought into solution by urea solubilization. This procedure allows for the lysis of the cells in a metabolically inactive state, preserving phosphorylation and preventing reorientation of the phosphoproteome during cell lysis.  Following reduction, alkylation, trypsin digestion of the proteins, the samples are desalted on C18 columns and the sample complexity reduced by fractionation using hydrophilic interaction chromatography (HILIC). HILIC columns preferentially retain hydrophilic molecules which is well suited for phosphoproteomics.  Phosphorylated peptides tend to elute later in the chromatographic profile than the non phosphorylated counterparts. After fractionation, phosphopeptides are enriched using immobilized metal chromatography, which relies on charge-based affinities for phosphopeptide enrichment. At the end of this procedure the samples are ready to be quantitatively analyzed by mass spectrometry.

Quantitative Phosphoproteomics in Fatty Acid Stimulated Saccharomyces cerevisiae

Description of a quantitative phosphorylation procedure using cryolysis, urea solubilziation, HILIC fractionation and IMAC enrichment of phosphorylated peptides.

This protocol describes the growth and stimulation, with the fatty acid oleate, of isotopically heavy and light S. cerevisiae cells. Cells are ground ...

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Human cancer and response to therapy is better represented in orthotopic animal models. This paper describes the development of an orthotopic mouse model of ovarian cancer, treatment of cancer via oral delivery of drugs, and monitoring of tumor cell behavior in response to drug treatment in real time using in vivo imaging system. In this orthotopic model, ovarian tumor cells expressing luciferase are applied topically by injecting them directly into the mouse bursa where each ovary is enclosed. Upon injection of D-luciferin, a substrate of firefly luciferase, luciferase-expressing cells generate bioluminescence signals. This signal is detected by the in vivo imaging system and allows for a non-invasive means of monitoring tumor growth, distribution, and regression in individual animals. Drug administration via oral gavage allows for a maximum dosing volume of 10 mL/kg body weight to be delivered directly to the stomach and closely resembles delivery of drugs in clinical treatments. Therefore, techniques described here, development of an orthotopic mouse model of ovarian cancer, oral delivery of drugs, and in vivo imaging, are useful for better understanding of human ovarian cancer and treatment and will improve targeting this disease.

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Orthotopic animal models of ovarian cancer replicate better human disease and therefore enhance our understanding of cancer progression and tumor response to therapy. A mouse model receives an intrabursal injection of luciferase-expressing ovarian tumor cells. Treatment is administered via oral gavage. Tumor growth is monitored by in vivo imaging system.

Human cancer and response to therapy is better represented in orthotopic animal models.  This paper describes the development of an orthotopic mouse model ...

GC-based Detection of Aldononitrile Acetate Derivatized Glucosamine and Muramic Acid for Microbial Residue Determination in Soil

Quantitative approaches to characterizing microorganisms are crucial for a broader understanding of the microbial status and function within ecosystems. Current strategies for microbial analysis include both traditional laboratory culture-dependent techniques and those based on direct extraction and determination of certain biomarkers1, 2. Few among the diversity of microbial species inhabiting soil can be cultured, so culture-dependent methods introduce significant biases, a limitation absent in biomarker analysis.
The glucosamine, mannosamine, galactosamine and muramic acid have been well served as measures of both the living and dead microbial mass, of these the glucosamine (most abundant) and muramic acid (uniquely from bacterial cell) are most important constituents in the soil systems3, 4. However, the lack of knowledge on the analysis restricts the wide popularization among scientific peers. Among all existing analytical methods, derivatization to aldononitrile acetates followed by GC-based analysis has emerged as a good option with respect to optimally balancing precision, sensitivity, simplicity, good chromatographic separation, and stability upon sample storage5.
Here, we present a detailed protocol for a reliable and relatively simple analysis of glucosamine and muramic acid from soil after their conversion to aldononitrile acetates. The protocol mainly comprises four steps: acid digestion, sample purification, derivatization and GC determination. The step-by-step procedure is modified according to former publications6, 7. In addition, we present a strategy to structurally validate the molecular ion of the derivative and its ion fragments formed upon electron ionization. We applied GC-EI-MS-SIM, LC-ESI-TOF-MS and isotopically labeled reagents to determine the molecular weight of aldononitrile acetate derivatized glucosamine and muramic acid; we used the mass shift of isotope-labeled derivatives in the ion spectrum to investigate ion fragments of each derivatives8. In addition to the theoretical elucidation, the validation of molecular ion of the derivative and its ion fragments will be useful to researchers using &delta;13C or ion fragments of these biomarkers in biogeochemical studies9, 10.

We describe a method protocol for the GC-based analysis of the aldonitrile acetate derivatives of glucosamine and muramic acid extracted from soil. For elucidation of the chemical mechanism, we also present a strategy to confirm the structure of the derivative and the ion fragments formed upon electron ionization.

Quantitative approaches to characterizing microorganisms are crucial for a broader understanding of the microbial status and function within ecosystems. ...

Isolation and Primary Culture of Rat Hepatic Cells

Primary hepatocyte culture is a valuable tool that has been extensively used in basic research of liver function, disease, pathophysiology, pharmacology and other related subjects. The method based on two-step collagenase perfusion for isolation of intact hepatocytes was first introduced by Berry and Friend in 1969 1 and, since then, has undergone many modifications. The most commonly used technique was described by Seglenin 1976 2. Essentially, hepatocytes are dissociated from anesthetized adult rats by a non-recirculating collagenase perfusion through the portal vein. The isolated cells are then filtered through a 100 &mu;m pore size mesh nylon filter, and cultured onto plates. After 4-hour culture, the medium is replaced with serum-containing or serum-free medium, e.g. HepatoZYME-SFM, for additional time to culture. These procedures require surgical and sterile culture steps that can be better demonstrated by video than by text. Here, we document the detailed steps for these procedures by both video and written protocol, which allow consistently in the generation of viable hepatocytes in large numbers.

Primary hepatocytes provide a valuable tool to evaluate biochemical, molecular, and metabolic functions in a physiologically relevant experimental system. We describe a reliable protocol for rat in situ liver perfusion, which consistently generates viable hepatocytes up to 1.0 &times; 108 cells per preparation with cell viability between 88 ~ 96%.

Primary hepatocyte culture is a valuable tool that has been extensively used in basic research of liver function, disease, pathophysiology, pharmacology ...

Application of Retinoic Acid to Obtain Osteocytes Cultures from Primary Mouse Osteoblasts

The need for osteocyte cultures is well known to the community of bone researchers; isolation of primary osteocytes is difficult and produces low cell numbers. Therefore, the most widely used cellular system is the osteocyte-like MLO-Y4 cell line.
The method here described refers to the use of retinoic acid to generate a homogeneous population of ramified cells with morphological and molecular osteocyte features.
After isolation of osteoblasts from mouse calvaria, all-trans retinoic acid (ATRA) is added to cell medium, and cell monitoring is conducted daily under an inverted microscope. First morphological changes are detectable after 2 days of treatment and differentiation is generally complete in 5 days, with progressive development of dendrites, loss of the ability to produce extracellular matrix, down-regulation of osteoblast markers and up-regulation of osteocyte-specific molecules.
Daily cell monitoring is needed because of the inherent variability of primary cells, and the protocol can be adapted with minimal variation to cells obtained from different mouse strains and applied to transgenic models. 
The method is easy to perform and does not require special instrumentation, it is highly reproducible, and rapidly generates a mature osteocyte population in complete absence of extracellular matrix, allowing the use of these cells for unlimited biological applications.

Treatment of primary mouse osteoblasts with retinoic acid produces a homogeneous population of ramified cells bearing morphological and molecular features of osteocytes. The method overcomes the difficulty of obtaining and maintaining primary osteocytes in culture, and can be advantageous to study cells derived from transgenic models.&#160;

The need for osteocyte cultures is well known to the community of bone researchers; isolation of primary osteocytes is difficult and produces low cell ...

Protocol for Isolation of Primary Human Hepatocytes and Corresponding Major Populations of Non-parenchymal Liver Cells

Beside parenchymal hepatocytes, the liver consists of non-parenchymal cells (NPC) namely Kupffer cells (KC), liver endothelial cells (LEC) and hepatic Stellate cells (HSC). Two-dimensional (2D) culture of primary human hepatocyte (PHH) is still considered as the &#34;gold standard&#34; for in vitro testing of drug metabolism and hepatotoxicity. It is well-known that the 2D monoculture of PHH suffers from dedifferentiation and loss of function. Recently it was shown that hepatic NPC play a central role in liver (patho-) physiology and the maintenance of PHH functions. Current research focuses on the reconstruction of in vivo tissue architecture by 3D- and co-culture models to overcome the limitations of 2D monocultures. Previously we published a method to isolate human liver cells and investigated the suitability of these cells for their use in cell cultures in Experimental Biology and Medicine1. Based on the broad interest in this technique the aim of this article was to provide a more detailed protocol for the liver cell isolation process including a video, which will allow an easy reproduction of this technique.
Human liver cells were isolated from human liver tissue samples of surgical interventions by a two-step EGTA/collagenase P perfusion technique. PHH were separated from the NPC by an initial centrifugation at 50 x g. Density gradient centrifugation steps were used for removal of dead cells. Individual liver cell populations were isolated from the enriched NPC fraction using specific cell properties and cell sorting procedures. Beside the PHH isolation we were able to separate KC, LEC and HSC for further cultivation.
Taken together, the presented protocol allows the isolation of PHH and NPC in high quality and quantity from one donor tissue sample. The access to purified liver cell populations could allow the creation of in vivo like human liver models.

A technique to isolate human hepatocytes and non-parenchymal liver cells from the same donor is described. The different liver cell types build the basis for functional liver models and tissue engineering. This new method aims to isolate liver cells in a high yield and viability.

Beside parenchymal hepatocytes, the liver consists of non-parenchymal cells (NPC) namely Kupffer cells (KC), liver endothelial cells (LEC) and hepatic ...

Methods for the Determination of Rates of Glucose and Fatty Acid Oxidation in the Isolated Working Rat Heart

The mammalian heart is a major consumer of ATP and requires a constant supply of energy substrates for contraction. Not surprisingly, alterations of myocardial metabolism have been linked to the development of contractile dysfunction and heart failure. Therefore, unraveling the link between metabolism and contraction should shed light on some of the mechanisms governing cardiac adaptation or maladaptation in disease states. The isolated working rat heart preparation can be used to follow, simultaneously and in real time, cardiac contractile function and flux of energy providing substrates into oxidative metabolic pathways. The present protocol aims to provide a detailed description of the methods used in the preparation and utilization of buffers for the quantitative measurement of the rates of oxidation for glucose and fatty acids, the main energy providing substrates of the heart. The methods used for sample analysis and data interpretation are also discussed. In brief, the technique is based on the supply of 14C- radiolabeled glucose and a 3H- radiolabeled long-chain fatty acid to an ex vivo beating heart via normothermic crystalloid perfusion. 14CO2 and 3H2O, end byproducts of the enzymatic reactions involved in the utilization of these energy providing substrates, are then quantitatively recovered from the coronary effluent. With knowledge of the specific activity of the radiolabeled substrates used, it is then possible to individually quantitate the flux of glucose and fatty acid in the oxidation pathways. Contractile function of the isolated heart can be determined in parallel with the appropriate recording equipment and directly correlated to metabolic flux values. The technique is extremely useful to study the metabolism/contraction relationship in response to various stress conditions such as alterations in pre and after load and ischemia, a drug or a circulating factor, or following the alteration in the expression of a gene product.

The following protocol describes the preparation and utilization of buffers for the quantitative measurement of rates of glucose and fatty acid oxidation in the isolated working rat heart. The methods used for sample analysis and data interpretation are also discussed.

The mammalian heart is a major consumer of ATP and requires a constant supply of energy substrates for contraction. Not surprisingly, alterations of ...

Isolation and Culture of Primary Mouse Keratinocytes from Neonatal and Adult Mouse Skin

The keratinocyte (KC) is the predominant cell type in the epidermis, the outermost layer of the skin. Epidermal KCs play a critical role in providing skin defense by forming an intact skin barrier against environmental insults, such as UVB irradiation or pathogens, and also by initiating an inflammatory response upon those insults. Here we describe methods to isolate KCs from neonatal mouse skin and from adult mouse tail skin. We also describe culturing conditions using defined growth supplements (dGS) in comparison to chelexed fetal bovine serum (cFBS). Functionally, we show that both neonatal and adult KCs are highly responsive to high calcium-induced terminal differentiation, tight junction formation and stratification. Additionally, cultured adult KCs are susceptible to UVB-triggered cell death and can release large amounts of TNF upon UVB irradiation. Together, the methods described here will be useful to researchers for the setup of in vitro models to study epidermal biology in the neonatal mouse and/or the adult mouse.

Epidermal keratinocytes form a functional skin barrier and are positioned at the front line of host defense against external environmental insults. Here we describe methods for isolation and primary culture of epidermal keratinocytes from neonatal and adult mouse skin, and induction of terminal differentiation and UVB-triggered inflammatory response from keratinocytes.

The keratinocyte (KC) is the predominant cell type in the epidermis, the outermost layer of the skin. Epidermal KCs play a critical role in providing skin ...

Isolation and 3D Collagen Sandwich Culture of Primary Mouse Hepatocytes to Study the Role of Cytoskeleton in Bile Canalicular Formation In Vitro

Hepatocytes are the central cells of the liver responsible for its metabolic function. As such, they form a uniquely polarized epithelium, in which two or more hepatocytes contribute apical membranes to form a bile canalicular network through which bile is secreted. Hepatocyte polarization is essential for correct canalicular formation and depends on interactions between the hepatocyte cytoskeleton, cell-cell contacts, and the extracellular matrix. In vitro studies of hepatocyte cytoskeleton involvement in canaliculi formation and its response to pathological situations are handicapped by the lack of cell culture, which would closely resemble the canaliculi network structure in vivo. Described here is a protocol for the isolation of mouse hepatocytes from the adult mouse liver using a modified collagenase perfusion technique. Also described is the production of culture in a 3D collagen sandwich setting, which is used for immunolabeling of cytoskeletal components to study bile canalicular formation and its response to treatments in vitro. It is shown that hepatocyte 3D collagen sandwich cultures respond to treatments with toxins (ethanol) or actin cytoskeleton altering drugs (e.g., blebbistatin) and serve as a valuable tool for in vitro studies of bile canaliculi formation and function.

Presented here is a protocol for the isolation of mouse hepatocytes from adult mouse livers using a modified collagenase perfusion technique. Also described is the long-term culture of hepatocytes in a 3D collagen sandwich setting as well as immunolabeling of the cytoskeletal components to study bile canalicular formation and its response to treatment.

Hepatocytes are the central cells of the liver responsible for its metabolic function. As such, they form a uniquely polarized epithelium, in which two or ...

Isolation of Primary Rat Hepatocytes with Multiparameter Perfusion Control

Primary hepatocytes are widely used in basic research on liver diseases and for toxicity testing in vitro. The two-step collagenase perfusion procedure for primary hepatocyte isolation is technically challenging, especially in portal vein cannulation. The procedure is also prone to occasional contamination and variations in perfusion conditions due to difficulties in the assembly, optimization, or maintenance of the perfusion setup. Here, a detailed protocol for an improved two-step collagenase perfusion procedure with multiparameter perfusion control is presented. Primary rat hepatocytes were successfully and reliably isolated by taking the necessary technical precautions at critical steps of the procedure, and by reducing the operational difficulty and mitigating the variability of perfusion parameters through the adoption of a special intravenous catheter, standardized sterile disposable tubing, temperature control, and real-time monitoring and alarm system. The isolated primary rat hepatocytes consistently exhibit high cell viability (85%-95%), yield (2-5 x 108 cells per 200-300 g rat) and functionality (albumin, urea and CYP activity). The procedure was complemented by an integrated perfusion system, which is compact enough to be set up in the laminar flow hood to ensure aseptic operation.

This protocol details the use of a special intravenous catheter, standardized sterile disposable tubing, temperature control complemented by real-time monitoring, and an alarm system for two-step collagenase perfusion procedure to improve the consistency in the viability, yield, and functionality of isolated primary rat hepatocytes.

Primary hepatocytes are widely used in basic research on liver diseases and for toxicity testing in vitro. The two-step collagenase perfusion procedure ...