Introduction

Hepatocytes play a major role in a variety of metabolic processes. After absorption from the gut, chemicals are transported to the liver where they may be converted to pharmacologically active or toxic metabolites or to hydrophilic excretable conjugates. Important components of the enzyme system needed for the metabolism of xenobiotics are a group of hemoproteins collectively known as the cytochrome P450 (CP450) system  which function by oxidative metabolism. A characteristic property of this enzyme system is its inducibility by many chemicals or lipophilic substances associated with enhanced microsomal oxidation1,2. These inducers can be divided into three broad classes typified by drugs like phenobarbital, polycyclic hydrocarbons like benzo(a)pyrene and steroids such as testosterone3,4.

Other than the problems normally associated with mammalian cell culture, a major limitation of rodent hepatocytes in traditional serum-supplemented culture has been the rapid loss (90% by day 2) of CP450 catalyzed Phase I reactions (oxidation, hydroxylation, reduction)5. Attempts to overcome this problem have focused on the culture of hepatocytes on specialized matrices, media formulations and media supplementation6. Life Technologies scientists have focused on the optimization of a media family for the isolation, culture and phenotypic expression of hepatocytes. The purification of viable hepatocytes is achieved using either Nycodenz or Percoll density gradients.

Hepatocyte serum-free medium has been compared to both serum-supplemented and serum-free controls using either EHS or Collagen I as a matrix. Results have repeatedly shown a significant improvement in the maintenance and inducibility of the two measured enzymes, ethoxycoumarin de-ethylase and benzo-a-pyrene hydroxylase.

Caution: Human origin materials are non-reactive (donor level) for anti-HIV 1 & 2, anti-HCV, and HBsAg. Handle in accordance with established bio-safety practices.

This is a serum-free medium for the long-term maintenance of hepatocyte phenotypic expression including the active and inducible forms of Cytochrome P450 and active phase II enzymes. This medium should be supplemented with 2 mM L-glutamine and 5 mL (1X) penicillin-streptomycin prior to use.

Features

The Hepatocyte Product Line

  • Transports the liver without ischemic damage
  • Media that maximizes viable cell yields
  • Maintains the xenobiotic metabolic activity of primary hepatocytes in culture

Quality Control Testing

All media have been demonstrated to support hepatocyte applications by performance testing using rat liver perfusion, digestion, culture and metabolic activity measurement. Standard testing for the product range includes pH, osmolality and tests for the absence of bacterial and fungal contaminants

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Instructions for using the Hepatocyte Products

Note:   Please refer to description of products for respective media supplementation.

  1. Adult Sprague-Dawley male rats (300 to 350 gms) are anesthetized with Ketamine and xylazine (60:5 mg/kg) given intramuscularly or with chlorohydrate (345 mg/kg).
  2. The liver is isolated in situ and perfused with 350 mL of warm (37°C) Liver Perfusion Medium through the abdominal aorta (ligated below the kidneys and above the diaphragm) at a rate of 35 mL/minute with the perfusate exiting through the severed vena cava.
  3. This is followed by a Collagenase-Dispase digestion with Liver Digest Medium at a rate of 35 mL/minute. This results in blanching, softening and dissociation of liver tissue and provides complete digestion of the liver in 10-12 minutes.
  4. The liver is aseptically removed to a sterile 50 mL conical tube containing 15mL cold L-15 Medium and transferred to the cell culture laboratory on ice.
  5. The hepatocytes are released by gently using a cell scrapper and pipetting with a large bore pipette. The cell suspension is spun down at 50 g for 5 minutes, resuspended in wash media and filtered through a sterile 100 μm nylon meshinto a 50 mL conical tube placed on ice, sedimented by centrifugation at 50 g for 5 minutes, resuspended and washed 2-3 times in 50 mL cold Hepatocyte Wash Medium.
  6. Hepatocytes are purified by centrifugation on either 20% NYCODENZ® or alternatively by Percoll density gradient separation and washed twice more before being resuspended in the attachment medium. Either of these separation procedures give a cell yield of about 2.5 x 108 cells with 90-95% viability, as determined by trypan blue exclusion.
  7. Approximately 10 x 106 cells in 25 mL of Williams' Medium E, supplemented with 5mL penicillin-streptomycin and either 5μg/cm2 bovine fibronectin or 5% FBS are plated in 150-cm2 tissue culture flasks precoated with a Collagen 17matrix (12.5 μg/cm2) or with the EHS matrix8 (100 μg/cm2 Matrigel, Collaborative Research Inc., Bedford, MA) and incubated in a humidified atmosphere of 5% CO2 in air at 37°C. Collagen or EHS is diluted in ice cold 1X HBSS (Cat. No. 14170) and 20 mL/T160 cm2 flask added, spread over the surface and incubated overnight at 37°C. The flasks should be washed with the Wash Medium prior to adding the cell suspension.
  8. Unattached cells are poured off 2-3 hours after plating and replaced with 25 mL HepatoZYME-SFM supplemented with 1.25 μg/cm2 rat tail Collagen to provide a sandwich matrix9. Cultures are re-fed with Hepatocyte SFM (without collagen) at 24 hours and every 48 hours thereafter. Hexobarbital (0.5-2.0mM) or other inducing agents may be added to cultures 48 hours before harvesting the cells.

Analytical Procedures: The cells are harvested by scraping into ice-cold 100 mM KPO4 buffer (pH 7.4) sonicated and fractionated to yield a microsomal pellet that may be frozen at -70°C prior to use. The pellet is homogenized in a buffer containing protease inhibitors and used for protein, Western blot and enzyme analysis.

NYCODENZ® is a trademark of Nycomed Pharma, AS.
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References

  1. Guengerich, F.P., Isolation and purification of cytochrome P-450, and the existence of multiple forms. Pharmacol. Therap. 6:99-121 (1979).

  2. Guzelian, P.S., Bissell, D.M., Meyer, U.A., Drug metabolism in adult rat hepatocytes in primary monolayer culture. Gastroentrology 72:1232-1236 (1977).

  3. Michalopoulos, G., Sattler, C.A., Sattler, G.L., and Pitot, H.C. Cytochrome P- 450 induction by phenobarbital and methylcholanthrene in primary cultures of hepatocytes. Science 193:907-909 (1976).

  4. Nebert, D.W. and Gelboin, H.V., Substrate-inducible microsomal Aryl Hydroxylase in mammalian cell culture. J Biol. Chem. 243:6242-6249 (1968).

  5. Paine, A.J., Williams, L.J. and Legg, R.F., Apparent maintenance of cytochrome P-450 by Nicotinamide in primary cultures of rat hepatocytes. Life Sciences 24:2185-2192 (1979).

  6. Guegen-Guillouzo, C., Isolation and culture of animal and human hepatocytes in Culture of epithelial cells pp 197-223. Wiley-Liss,Inc. (1992).

  7. Price, P.J. Preparation and use of rat-tail Collagen. TCA Manual 1:43-44 (1975).

  8. Rojkind, M., Gatmaitan, Z., Mackensen, S., Giambrone, M., Ponce, P., and Reid, L.M. Connective Tissue Biomatrix: Its isolation and utilization for longterm cultures of normal rat hepatocytes. J Cell Biol. 87:255-263 (1980).

  9. Dunn, J.C., Yarmush, M.L., Koebe, H.G. and Tompkins, R.G. Hepatocyte function and extracellular matrix geometry: long-term culture in a sandwich configuration. FASEB J. 3:174-177 (1989).
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LT143                          8-Mar-2011