Use of athymic nude mice for in vivo studies of human growth-hormone-secreting pituitary adenomas.

Human growth hormone (hGH)-secreting pituitary adenoma tissue of 31 acromegalic patients was transplanted subcutaneously onto 291 athymic nude mice. 37% of the transplanted adenoma fragments could be maintained vital up to 46 days. Histological examinations of the transplants revealed neither alterations in their morphological characteristics nor signs of growth. A maintenance or linear decline of hGH secretion of the transplants related to their vitality was observed by hGH radioimmunoassay. Estimation of graft vitality was improved by GH-releasing hormone (GHRH) stimulation in regular intervals. The rate of pituitary adenomas responding to GHRH was as high as in a major collective of acromegalic patients. Our method of positive selection of vital xenotransplanted hGH-secreting pituitary adenomas via hGH detection at regular intervals in combination with GHRH stimulation gives the opportunity of reliable in vivo research with these tumors.