This study constructed an in situ cell culture, real-time observation system based originally on a microfluidic channel, and reported the morphological changes of late osteoblast-like IDG-SW3 cells in response to flow shear stress (FSS). The effects of high (1.2 Pa) and low (0.3 Pa) magnitudes of unidirectional FSS and three concentrations of extracellular Type I collagen (0.1, 0.5, and 1 mg/mL) coating on cell morphology were investigated. IDG-SW3 cells were cultured in polydimethylsiloxane microfluidic channels. Cell images were recorded real-time under microscope at intervals of 1 min. Cell morphology was characterized by five parameters: cellular area, cell elongation index, cellular alignment, cellular process length, and number of cellular process per cell. Immunofluorescence assay was used to detect stress fiber distribution and vinculin expression. The results showed that 1.2 Pa, but not 0.3 Pa of FSS induced a significant morphological change in late osteoblast-like IDG-SW3 cells, which may be caused by the alteration of cellular adhesion with matrix in response to FSS. Moreover, the amount of collagen matrix, alignment of fiber stress and expression of vinculin were closely correlated with the morphological changes of IDG-SW3 cells. This study suggests that osteoblasts are very responsive to the magnitudes of FSS, and extracellular collagen matrix and focal adhesion are directly involved in the morphological changes adaptive to FSS.
Keywords: Cell morphology; Flow shear stress; Microfluidic chip; Osteoblast.