Growth of human pheochromocytomas in the anterior eye chamber of the rat. A histochemical study on amine and peptide content of pheochromocytoma tumour cells.

Tissue pieces from seven benign human pheochromocytomas have been successfully transplanted to the anterior eye chamber of cyclosporin-treated rats. In vivo observations showed that 74-99% of the tumour transplants were vascularized within one to two days after transplantation. No increase in the size of the transplants was noted during the observation period (1-4 weeks). Tumour transplants grown in non-immunosuppressed rats were initially vascularized but rejection started to occur one week after transplantation. Histochemical analysis of tumour transplants grown in immunosuppressed rats demonstrated numerous tumour cells with strong catecholamine fluorescence, some of which formed long cell processes on the host iris. Immunocytochemical analysis of tumour transplants demonstrated positively labelled tumour cells after incubation with antisera against neuropeptide Y, enkephalin, vasoactive intestinal polypeptide, somatostatin, substance P, dopamine-beta-hydroxylase, tyrosine hydroxylase and serotonin. A similar histochemical and immunocytochemical pattern was observed in primary tumours but tumour cells sending out cell processes were observed less frequently. Human pheochromocytomas may thus be successfully grown in oculo in cyclosporin-treated rats. This may prove to be a suitable model for the study of storage and release of catecholamines and neuropeptides from pheochromocytoma tumour cells.