The overall goal of this procedure is to successfully isolate functional murine hepatocytes for studying the expression and secretion of inflammatory cytokines such as CRP and IL6 in response to mediators of the hepatic acute phase response. This method could help answer key questions of hepatocellular function and the contribution of hepatic cytokines to a prolonged inflammatory environment as found in chronic kidney disease. The main advantage of this technique is that it provides a robust tool for a simple, fast, and reproducible analysis of hepatic metabolomics and inflammation as well as a response to drugs.
To begin, preheat the liver perfusion medium and liver digest medium in a water bath at 37 degrees Celsius. Set up a perfusion pump as shown here. Then use liver perfusion medium to carefully pre-fill the tubing system of the pump.
Try avoiding any air bubbles in the system. Prepare the stereotactic microscope for the perfusion procedure. Then after anesthetizing a donor mouse according to the text protocol, place the anesthetized animal on an absorbent pad.
Use adhesive tape to fix the mouse's extremities. Next, shave and disinfect the abdomen of the mouse. Then use surgical scissors with sharp blunt tips to perform a ventral laparotomy from the pubis to the cranial border of the liver.
Incise the abdominal wall on both sides at a position caudal to the diaphragm. Expose the inferior vena cava or IVC by carefully moving the intestine to the right side using sterile cotton swabs. With fine surgical scissors and sharp sharp tips, make lateral incisions across the suprahepatic diaphragm and open the thoracic cavity.
Then use 5-0 surgical silk to ligate the thoracic IVC. With a shielded IV catheter, cannulate the infrarenal IVC. Connect the perfusion pump and start perfusing the liver.
If performed properly, the liver should immediately begin to blanch and swell. Next, with fine surgical scissors, transect the portal vein, allowing suitable drainage of blood and perfusion medium. After perfusing the liver with approximately 30 milliliters of liver perfusion medium, stop the perfusion pump.
Switch to liver digest medium and resume the pump. Once perfusion is complete, remove the cannula. Gently expose the central region of the liver and locate the connecting tissue linking the liver lobes.
Grab the central connecting fibers and carefully dissect all the tissues holding the liver in place. Then gently remove the liver. Immediately transfer the organ into a 50 milliliter polypropylene conical tube containing 15 milliliters of liver digest medium.
While working under a cell culture hood, transfer the liver from the 50 milliliter polypropylene conical tube into a sterile tissue culture dish. With sterile forceps, gently tear the four lobes of the liver. If performed properly, the digestion medium should become turbid duet to the isolation of hepatocytes from the liver.
Using a 25 milliliter sterile pipette tip, filter the turbid digestion medium through a 70 micrometer nylon cell strainer into a new 50 milliliter polypropylene conical tube to remove undigested tissue particles and cell debris. Centrifuge the combined filtrate at 50 times g in four degrees Celsius for two minutes, then aspirate the supernatant containing excess cell debris and use 25 milliliters of cold 1X William's Medium E to gently resuspend cells. After repeating the filtering and washing of the hepatocytes three times, aspirate the supernatant to remove excess cell debris.
Resuspend the cells in 25 milliliters of warm 1X William's Medium E that contains primary hepatocyte thawing and plating supplements and filter the suspension through a new 70 micrometer nylon cell strainer into a 50 milliliter conical tube. Once the cells have been counted, plate them in two milliliters of William's Medium E that contains primary hepatocyte thawing and plating supplements on a collagen-coated six well cell culture cluster. Following two changes of medium to eventually starve the cells, treat the cells with PBS as vehicle, 25 nanograms per milliliter of FGF23, 100 micrograms per milliliter of LPS, or 50 nanograms per milliliter of IL6 in serum-free medium.
Incubate the cultures for 24 hours. After preparing RNA using a spin column kit according to the manufacturer's instructions, add 200 nanograms of the isolated RNA to a PCR tube. Then add 14 microliters of endonuclease-free water and four microliters of reverse transcriptase to the tube.
Place the PCR tube into the thermocycler and run the following reverse transcription program to generate cDNA. To carry out quantitative PCR, combine the following QPCR master mix components in a tube on ice. Vortex the master mix.
Then aliquot nine microliters of the solution into each well of a 96 well plate. Carefully add one microliter of cDNA into each well, preparing three wells for each sample. Finally, run the samples in a real-time PCR instrument and analyze the data according to the text protocol.
A representative light microscopy image of primary isolated and cultured cells are depicted here. Immunocytochemical analysis demonstrates that isolated hepatocytes highly express albumin as well as fibroblast growth factor receptor 4. In this experiment, primary isolated hepatocytes were treated with FGF23, LPS, or IL6 for 24 hours and mRNA levels of CRP and IL6 were analyzed by quantitative real-time PCR.
LPS, IL6, and FGF23 significantly increased expression of CRP and IL6. As shown here, cell culture supernatants from isolated primary hepatocytes were analyzed by ELISA for CRP levels. As demonstrated with QPCR analysis, LPS, IL6, and FGF23 treatments significantly increased CRP levels in cell supernatants when compared to PBS-treated cells.
Once mastered, this technique can be done in just a few hours if it is performed properly. While attempting this procedure, it's important to remember to maintain a sterile environment. Due to working with primary culture, minimizing the risk of possible contamination is most important for achieving optimal results.
After watching this video, you should have a good understanding of how to successfully isolate murine hepatocytes for studying various hepatocellular functions such as expression and secretion of hepatic cytokines.
