CELLS OF DIFFERENT TISSUES FOR IN-VITRO AND IN-VIVO STUDIES IN TOXICOLOGY - COMPILATION OF ISOLATION METHODS

An advantage of using freshly isolated intact cells of different organ s in toxicology is that they reflect more closely the in vivo situatio n than do long-term cultures. In vitro, primary cells provide the poss ibility of determining cell-specific xenobiotic metabolism, in the abs ence of artificial extracellular activation systems, which may result in cytotoxic and genotoxic effects. After in vitro exposure of animals to xenobiotics, isolated primary cells can be studied to elucidate to xicokinetic effects. In the review presented here. selected methods ar e described for isolating cells with high viability from pig liver and avian embryonic liver, and from the nasal cavity, lungs, kidneys, gas tro-intestinal tract, urinary bladder, testes and thymus of the rat. T wo techniques for preparing rat lymphocytes are also described. Cell i solation may be initiated with an in situ perfusion to clear the organ of blood. Steps to loosen cell-to-cell contacts and to digest the int ercellular connective material may then follow. Also, in situ digestio n may be performed, as described for the epithelial cells from differe nt mucosal tissues. Following initial digestion, a single-cell suspens ion is prepared by tissue mincing and a second digestive step with pro teolytic enzymes. Frequently used digestive enzymes are collagenase (t ypes I, IV and P; from Clostridium histolyticum), trypsin and proteina se K. Follow-up filtration is usually required to remove undigested ma terial. The quantities and viabilities of the harvested cells vary wit h the organ of choice and the procedure used; the values obtained are stated.