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The effect of combined simulated microgravity and microgrooved surface topography on fibroblasts.  WA Loesberg¹, XF Walboomers¹, JJWA Van Loon², JA Jansen^{1 1}Dept. Periodontology & Biomaterials, Radboud Univ., Nijmegen, The Netherlands, ²DESC OCB-ACTA, Vrije Univ., Amsterdam, The Netherlands.

   This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 0.5 mm, width: 1, 2, 5, 10 mm), which undergo simulated microgravity by means of RPM. The aim of the study was to clarify which of these parameters was more dominant to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell alignment and area. Confocal laser scanning microscopy visualised distribution of actin filaments and vinculin anchoring points through immuno-staining. Finally, expression of collagen type I, fibronectin, and a1- and b1-integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata cells spread out in a random fashion. The alignment of cells cultured on grooved surfaces decreased under simulated microgravity, especially after 24 hours of culturing. Cell surface area on grooved substrata were significantly smaller than on smooth substrata. Simulated microgravity on the grooved groups resulted in an enlargement of cell area. ANOVA was performed on all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, gene levels were reduced by microgravity particularly those of b1-integrin and fibronectin. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by simulated microgravity.

(Supported by NWO-SRON: MG-057 & MG-063)