Teratological research using in vitro systems. IV. Cells in culture.

Abstract

Several in vitro cellular systems designed to screen agents for teratogenic potential are described in this report. These assays were selected from a review of literature published through the spring of 1986 that generated over 100 references on teratological research using cell-based systems. Some of the assays have a broader application than others, but most require confirmation by one or more additional complementary tests because of the specificity of the teratogenic mechanism the assays are investigating. Included are systems that use analysis of tumor cell attachment; intercellular communication; growth of human embryonic palatal mesenchyme cells; progesterone production in porcine granulosa cells; differentiation of embryonic neural crest, limb bud, midbrain, and Drosophila cells; and differentiation of tumor cells. Because of the dynamic nature of cell culture work, the group of assays listed here should not be viewed as encompassing all cell systems of value with regard to teratogenicity testing; instead, the list represents several of the more prominent systems now being evaluated by the scientific community. Inhibition of Tumor Cell Attachment to Concanavalin A-Coated Surfaces IntroductionInteractions between embryonic cells have long been thought to be critical factors in embryonic development. The breakdown of these intracellular communications by physical intervention or genetic defects are thought to be associated with developmental anomalies. Braun and associates (1) have described an in vitro cell-to-surface recognition system using mouse ascites tumor cells to screen for potential teratogens. The use of tumor cells in this type of assay has several advantages: tumor cells are readily available, homogeneous, easy to prepare, and share many characteristics with embryonic cells. One characteristic that transformed fibroblasts, tumor cells, and some embryonic cells share is the ability to attach themselves to lectin-coated plastic surfaces, whereas normal fibroblasts attach poorly. This difference has been exploited as a means of differentiating chemicals that alter cell-surface interactions from those that do not. Tumor cells have been shown to attach rapidly and irreversibly to lectin-coated plastic disks because of interactions between carbohydrate moieties on the cell membrane and lectin receptors on the plastic sur (1,3,4). Another measure used to assess an agent's effect is the concentration required in order to inhibit attachment by 50% (ID50). Critical ReviewAttempts have been made to validate this system with over 100 chemicals in two basic categories, drugs and pesticides. The lowest effective dose reported for a teratogen was used to estimate teratogenic potency; in considering nonteratogens, the highest reported nonteratogenic dose was used. Inhibitory agents included anti-inflammatory drugs, sedatives, estrogens, antibiotics, organophosphates, chlorophenols, chlorinated hydrocarbons, and chlorinated cyclodienes. Braun and associates (3) observed 14 false negatives on testing 74 chemic...