The Syrian hamster embryo (SHE) low pH cell transformation assay.

The Syrian hamster embryonic (SHE) cell transformation assay (CTA) at pH 6.7 can determine the ability of a test article to induce morphological transformation (MT) in cultured SHE cells. The assay uses SHE cells prepared at gestation day ∼13 and frozen. Target cells are seeded onto a layer of feeder cells (X-ray irradiated SHE cells) and treated with test article for 24 hr or 7 days. After a growth period of 7 days, the cells are fixed, stained, and evaluated for MT. Normal colonies typically contain a monolayer of cells with an organized, often flowing, pattern of growth and minimal cell criss-crossing at a confluent density. Transformed colonies contain randomly oriented, stacked cells, with cell criss-crossing throughout the colony. The transformed cells are frequently more basophilic than their normal counterparts, with increased nuclear/cytoplasmic ratios. This assay provides a valuable tool for evaluating the carcinogenic potential of a test article.