Human medullary carcinoma of the thyroid in tissue culture.

Medullary thyroid carcinomas (MCT) were obtained from patients with Sipple's syndrome or non-hereditary MCT. Cultures of enzymatically dissociated cells showed that MCT cells were mostly free-floating cells of epithelial characters. These MCT cells preserved the ability to secrete calcitonin for a long period of in vitro maintenance. However, the MCT cells under the usual culture conditions were filled with numerous cytoplasmic granules and appeared to be extremely fragile. When MCT cells were cultured in a low-calcium medium, such granules were not observed. In addition, MCT cells in the low-calcium medium increased the amount of calcitonin in response to added calcium and tetragastrin. Therefore, the culture of MCT cells in the low-calcium medium appeared to be useful for studies about the biochemical and physiological characters of human MCT cells in vitro.