Transplantation of human brain tumours into the brain of normal laboratory animals is still considered to be unsatisfactory by many researchers, despite the fact that the brain is considered an immunologically privileged site. We present in this paper a model of xenotransplantation fo human astrocytomas grade III-IV into the brain of normal, adult Sprague-Dawley rats with good take rates, i.e. takes in two thirds of the animals, half of these with large, infiltrating tumours. The transplants are placed using a microsurgical technique in the vessel-rich choroidal fissure in the host brain from where rapid vascularization occurs. The technique has previously been used for CNS-regeneration studies. This model should provide an excellent opportunity to study human malignant astrocytomas in a milieu as natural as possible.

Vessels in malignant brain tumors have a defective blood-brain barrier. It is important to know if tumor vessels respond to vasoactive agents, since systemic administration of vasodilatory agents together with chemotherapy could increase the access of these drugs to the tumor. It was found that arteries in human malignant gliomas have no neural control and are totally nonreactive to various vasoactive agents. The vessels lose their reactivity within 1 to 2 mm outside the visible tumor front.

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