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Simulated Microgravity Inhibits Proliferation of Malignant Glioma Cells.  M. Takeda¹, T. Okazaki¹, T. Magaki¹, A. Sasaki², S.L. Wu², Y. Kawahara^{2, 3}, R. Yoshimoto², T. Manabe², T. Kajiume¹, L. Yuge^2,3, and K. Kurisu¹. ¹Graduate School of Biomedical Sciences, ²Graduate School of Health Sciences, ³Space Bio-Laboratories Y. K., Hiroshima University, Japan.

   A 3D-clinostat is a multi-directional gravity device used for simulating microgravity. By controlled rotation of two axes, a 3D-clinostat minimizes the cumulative gravity vector in cells cultured at the center of the device and makes 10^-3 G average over time. In spite of recent advances in medical science, malignant gliomas are still refractory to treatment and have not shown any signs of improved prognosis.  It has been demonstrated that microgravity leads to some kind of deficiency of the biological function in clinical situation and suppresses the differentiation of various types of cells in vitro.  Therefore, we hypothesized that culture of glioma cells under the state of simulated microgravity may inhibit its proliferation. We investigated the effect of simulated microgravity on proliferation of D54 malignant glioma (D54MG) using a 3D-clinostat.

   Initially D54MGs were harvested in normal 1G condition.  Proliferated cells were, then, cultured in 3D-clinostat and normal 1G environment for 4 days.  The cells were examined for their growth pattern and the cell cycle difference using flow cytometry. 

   The cell number was found to decrease 2 times more in 3D-clinostat than in 1G environment.  However, the cell cycle analysis showed no difference between 3D-clinostat and 1G environment.  Thus, proliferation of D54MGs is inhibited probably due to its decelerated mitotic rate when cultured in a 3D-clinostat.

Malignant gliomas are still very difficult to treat and control. Though this report is preliminary, we suggest that the effect of microgravity may be of assistance to control malignant gliomas.