title: An optimal culture condition maintains human hepatocyte phenotype after long-term culture.
abstract: BACKGROUND
  Long-term culture of primary hepatocytes from various species is impeded by a decrease of cell viability and a loss of hepatocyte-specific function. The aim of the present study was to investigate whether our optimal culture condition (OC) can maintain the phenotype of primary hepatocytes in long-term culture.
  
  
  METHODS
  Primary human hepatocytes were cultured in either hepatocyte maintenance medium (HM) or OC for 2-4 weeks. Expression of hepatocyte-specific genes was determined by real-time quantitative RT-PCR.
  
  
  RESULTS
  The level of albumin mRNA in human hepatocytes cultured in OC was 11-fold more than in HM and gene expression levels of alpha1-antitrypsin and transferrin were at approximately 40 and 11% of freshly isolated primary human hepatocytes. Electron microscopy revealed that cells in OC displayed hepatocyte properties (e.g. polarity, junctional complexes, bile canaliculi and glycogen particles). Cytochrome P4501A1/2 activity of hepatocytes cultured in OC was 15- and 17-fold higher than in HM at 2 and 4 weeks of culture, and DNA synthesis was higher.
  
  
  CONCLUSIONS
  Using our optimal culture condition, we were able to maintain the phenotype of primary human hepatocytes in long-term culture. They not only maintain better liver-specific function, but also retain higher proliferative potential.
authors.affiliation: Transplant Research Institute, University of California, Davis Medical Center, Sacramento, CA 95817, USA.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Andreea M
authors.initials: AM
authors.lastname: Catana
authors.forename: Hongbo
authors.initials: H
authors.lastname: Cai
authors.forename: Stephen
authors.initials: S
authors.lastname: Strom
authors.forename: Phyllis M
authors.initials: PM
authors.lastname: Novikoff
authors.forename: Mark A
authors.initials: MA
authors.lastname: Zern