Development of a metastatic brain tumor model in mice.

This study reports an easily accomplished and reliable model of metastatic tumor in the brains of mice. Five experimental groups of female C3H/Bi mice received left intracardiac injections of a syngeneic KHT sarcoma cell suspension (1 X 10(5) cells) and were followed until death. Two groups of mice also received 3,000 rads of radiation to a limited cardiac port 24 hr after tumor injections. All mice were completely autopsied, and the brains were examined both grossly and microscopically. Metastatic brain tumor developed in 60 to 70% of mice; the tumor foci were parenchymal, usually multifocal, and had wide distribution throughout the cerebrum, brainstem, and cerebellum. There was occasional meningeal tumor, but tumor never involved the skull, choroid plexus, pituitary gland, or local extracranial structures. Cardiac irradiation did not increase the number of the mean survival of mice with metastatic brain tumor but did decrease the total tumor burden of individual animals by markedly reducing the incidence of metastatic lung tumor and totally preventing tumor infiltration of the heart. This demonstration of consistently produced blood-borne metastatic brain tumor in mice should provide a valuable research model which will allow the central nervous system to be studied for internal mechanisms and/or external factors which influence the arrest and growth of embolic tumor cells in the brain.