The effect of microgravity on gingival epithelial cells (GE1) is unknown; thus, we analyzed cell proliferation as well as the gene expression patterns in GE1 cells cultured under simulated microgravity.

Gingival epithelial cells were seeded and cultured at 10^-3 G in a three-dimensional clinostat to simulate microgravity (group CL) or in normal gravity (group C) for 10 days. Cell proliferation was analyzed by counting the numbers of cells. Real-time polymerase chain reaction was performed to amplify the krt 5, krt 13 and involucrin genes. Additionally, total protein was immunoblotted with anti-krt 13 antibody. Statistical analysis (n = 9, three groups repeated three times) was performed (ANOVA, Tukey's test, p < 0.05).

Cell proliferation was significantly upregulated under microgravity based on the average number of cells. Cell proliferation and differentiation marker expression was significantly increased after culture under simulated microgravity. Western blotting showed intense krt 13 staining under simulated microgravity. The simulated microgravity environment had an accelerating effect on GE1 proliferation and differentiation.

These findings suggest that GE1 cells would be affected by the microgravity environment during space flight. Moreover, these findings also suggest that we could promote regeneration of gingival cells using of a simulated microgravity environment.

Tamura A, Masaki C, Seo Y, Mukai C, Mukaibo T, Kondo Y, Nakamoto T, Hosokawa R. Microgravity might affect Peri-implant Mucosal Epithelial Cells during Space Flight. Int J Prosthodont Restor Dent 2015;5(1):10-16.