Liver epithelial cell isolation

In the heptatocyte-mediated mutagenesis studies, freshly isolated hepatocytes were mixed in a ratio of about 2 1 with liver epithelial cells before inoculation into culture flasks. After attachment, the two cell types were found to be well mixed and in close contact. Exposure of mixed cultures to several activation-dependent carcinogens that produce DNA repair in hepatocytes also produced mutagenesis in the cocultivated rat liver epithelial lines (Table 7) under conditions of exposure in which the carcinogens were not mutagenic to the lines in the absence of cocultivated hepatocytes. Thus, activated metabolites produced by the hepatocytes were transferred to the epithelial cells. Efforts to simplify this assay by the use of stored frozen hepatocytes are in progress. 

Parola, M., Cheeseman, K.H., Biocca, M.E., Dianzani, M.U. and Slater, T.F. (1988). Isolation and characterisation of biliary epithelial cells from normal rat liver J. Hepatol. 6, 175-186. 

In contrast to P-gp and the MRP proteins, the breast cancer resistance protein (BCRP) contains six transmembrane domains and only one ATP-binding domain. It was first cloned from the breast cancer cell line MCF-7 selected in doxombicin, in the presence of the P-gp inhibitor verapamil. It is found in many human tissues, such as the placenta, small intestine, colon, and liver [133], It is localized to the apical membrane of epithelial cells of the small intestine and colon and to the bile canalicular membrane in the liver and is involved in reducing intestinal uptake, increasing hepatobiliary excretion, etc., leading to diminished oral bioavailability. cDNA sequences identical to BCRP and named MXR and ABCP, respectively, were independently isolated from human colon carcinoma cells and human placenta [134], BCRP requires... 

Joplin, R., Strain, A J, and Neuberger, J. M. (1989) Immuno-isolation and culture of biliary epithelial cells from normal human liver In Vitro Cell Dev Biol 25, 1189-1192. 

Conjugation of 4-nitrophenol also occurred in cultured skin epithelial cells from humans (Rugstad and Dybing 1975), in isolated rat hepatocytes (Araya et al. 1986 Moldeus et al. 1976 Tonda and Hirata 1983), and in microsomes isolated from dog livers (Nakano et al. 1986). 

GGT does not nsnally form part of the standard LFTs in most laboratories. It is an enzyme fonnd in hepatocytes and biliary epithelial cells, and also in kidney, pancreas, intestine and prostate. It has a higher sensitivity for indicating a problem of liver origin than alkaline phosphatase, but tends to follow a similar pattern. It is released in all types of liver dysfunction and therefore cannot generally be used to differentiate between types. However, a raised GGT with an isolated raised alkaline phosphatase can be suggestive of cholestasis. GGT levels can be ten to 20 times normal in cholestatic disease. 

Numerous in vitro and/or in situ models have been developed to investigate drug metabolism. In order of decreasing complexity, they are the isolated perfused liver, isolated liver slices, hepatocytes in coculture with epithelial cells or bacteria, hepa-tocytes in suspension and in primary culture, subcellular hepatic microsomal S9 fractions and high-speed pellet microsomes. The field of metabolism is immense and will not be covered in depth here. However, one should have a basic understanding of the benefits and drawbacks of each one of these methods. ... 

Stem cells are progenitor cells which are not yet specifically formed. They can multiply almost infinitely and form nearly all 210 tissue types in the human being. Depending on their derivation, they are defined as follows .) embryonal (= taken from the inner cell mass of the blastocysts), (2.) foetal (= isolated from 5-9 week-old abortive foetuses, and (5.) adult (= taken from the tissue of adults or children by means of biopsy or from the umbilical cord of newborns. Adult stem cells are limited in number and life span they do, however, have a broader development potential than so far assumed. They have also been found in the liver. The transformation of stem cells from the bone marrow into hepatocytes has been carried out successfully. Liver stem cells (7-15 gm) can develop both primary cell types of the liver, (7.) mature hepatocytes and (2.) biliary epithelial cells. These stem cells are deemed to be genuine liver stem cells, and not merely derived from the activation of immature oval cells in the liver. (54,59, 60, 81) (s. fig. 2.20)... 

---