Changes in the Cell Division of Chang Liver Cells Induced by Simulated Microgravity

Background: Simulated microgravity (SMG) has not been well characterized in terms of its impact on cell division structures. This research aimed to assess the changes in cell division in Chang liver cells (CCL-13 cells) under SMG conditions. Methods: CCL-13 cells were exposed to SMG conditions via a 3D clinostat for 72 h. The cells from the control group were kept under the same conditions, without exposure to SMG. The changes in cell division were assessed via cell cycle progression analysis, the transcript expression of the genes associated with the cell cycle, and the appearance of the contractile ring, microvilli, and spindle in CCL-13 cells. Results: The CCL-13 cells from both the control group and the SMG group exhibited a typical epithelial-like shape. The CCL-13 cells of both groups displayed normal nuclear morphologies and were devoid of fragmentation and condensation, which are signs of apoptosis. There were changes in the cell cycle of CCL-13 cells in the SMG condition, which were shown via an increase in the cell percentage in the G0/G1 phase and a decrease in the S phase and G2/M phase. The cell area of the SMG-exposed CCl-13 cells increased, while their nuclear area decreased, which led to a reduction in the nuclear/cytoplasmic ratio. Moreover, the transcript expression of cyclin b1, cyclin d1, cdk2, and cdk6 was downregulated in CCL-13 cells under SMG conditions compared to the control group. Interestingly, SMG-exposed CCL-13 cells exhibited a decreased appearance of microvilli, changes in the formation of the contractile ring, and polar spindle microtubules during cytokinesis. Conclusions: SMG attenuated the cell division of CCL-13 cells by driving cells into the arrest phase and altering the cell division structures.