Blood-brain barrier permeability of human gliomas as determined by quantitation of cytoplasmic vesicles of the capillary endothelium and scintigraphic findings.

The number of cytoplasmic vesicles in the capillary endothelium was determined by ultrastructural morphometry and correlated with the uptake of technetium-99m pertechnetate used in brain scintigraphy. Ten gliomas were studied for uptake rates of 99mTc pertechnetate. Three gliomas from the different groups of uptake rates were quantitatively analyzed for cytoplasmic vesicle content. Capillaries of tumors without uptake had a low content of cytoplasmic vesicles, which was similar to that obtained in normal brain control. In tumors with low and moderate uptake rates, the cytoplasmic vesicles content increased significantly (p less than 0.05) by about 300% and 400%, respectively, as compared with that found in impermeable tumor and in normal brain. The correlation found between the cytoplasmic vesiculation of the endothelial cells in gliomas' capillaries and the uptake of 99mTc pertechnetate suggests that pinocytosis might be a factor in the uptake of the radionuclide. The present findings might be applicable to treatment with hydrophilic chemotherapeutic agents in moderate and highly permeable tumors.