A SERUM-FREE SYSTEM FOR PRIMARY CULTURES OF HUMAN PITUITARY-ADENOMAS

We report the successful use of a serum-free culture system for primar y cultures of human pituitary adenomas. The system utilizes histlotypi c suspension culture with low protein-binding membrane inserts that en able cells to retain their three-dimensional tissue configuration, clo sely mimicking the growth pattern in vivo. A serum-free defined medium was developed with CMRL-1969 (Connaught Willowdale Ontario, Canada) s upplemented with 0.375% albumin bovine Fraction V, 5 mu g/mL insulin, 5 mu g/mL transferrin, 5 ng/mL sodium selenite, 30 mu g/mL putrescine, 6.85 x 10(-11) M hydrocortisone, and 3.7 x 10(-11) M tri-iodothyronin e (T-3). We analyzed eight surgically resected human pituitary adenoma s. Basal pituitary hormone secretion measured by radioimmunoassay of p ituitary hormones was compared with hormone hypersecretion in vivo and with control cells of the same tumors cultured in CMRL-1969 with 10% fetal calf serum. The light microscopic, immunocytochemical, and ultra structural morphology of cells cultured in this serum-free histlotypic system was compared with cells cultured in serum-supplemented media a nd with cells cultured on collagen-coated plastic; all cultured cells were compared with the morphology of surgically resected tissues of th e same specimens. Basal pituitary hormone secretion during 24-hour inc ubations correlated with the clinical patterns of hormone excess; the data were similar in serum-enriched and serum-free cultures, however, hormone secretion decreased less rapidly in the serum-free cultures. C ells maintained in the histlotypic culture system closely resembled th e corresponding surgically resected tumor using the morphologic parame ters and were better preserved than those plated in collagen-coated pl astic wells. This comparative study indicates that this serum-free his tlotypic culture system provides an ideal method of examining pituitar y adenomas in vitro without altering the profile of hormone secretion and cell morphology documented in vivo. This system can be used to exa mine the production and effects of a wide range of hormones and growth factors that have been implicated as causative agents in pituitary tu morigenesis.