Stem cell studies of human malignant brain tumors. Part 2: Proliferation kinetics of brain-tumor cells in vitro in early-passage cultures.

The proliferation kinetics were studied in early-passage cultures of cells from 13 human malignant brain tumors and two specimens of normal brain under conditions similar to those used in clonogenic cell-survival studies. Autoradiography was performed in all but four cases to estimate the fraction of cells actively replicating deoxyribonucleic acid (DNA), the approximate cell cycle time, and the effect of low-dose tritiated thymidine on cell proliferation. The mean tumor cell doubling time (TD) was 53 hours for five glioblastomas, 46 hours for two ependymomas, and 83 hours for two medulloblastomas.