Hepatocytes directly isolated from liver tissue are called primary hepatocytes. The image on the left side is a schematic that shows the procedure for the isolation of primary human hepatocytes, and their cellular morphology in suspension and on plates. Decades of research and development has resulted in a robust isolation process for primary hepatocytes, yielding cultures with purities over 98%. Once isolated from the tissue, the hepatocytes may be used right away or cryopreserved for later use. The functionality of primary hepatocytes in culture is very similar to that of in vivo hepatocytes, as indicated by albumin production, urea production, and a variety of metabolic enzyme activities.
Many other cell culture models have been used to simulate the liver environment for research and development. Some of these alternative hepatocyte models include tumor cell lines such as Huh-7 and HepG2 cells. Tumor cell lines include the advantage of self-renewal, which saves resources and enables the more rapid production of genetic models for mechanistic research. However, the metabolic activity of tumor lines is 10-1,000 orders of magnitude less than that of primary hepatocytes and are not recommended for ADME-Tox studies where appropriate drug metabolism might be important.