Effect of uniaxial stretch on morphology and cytoskeleton of human mesenchymal stem cells: static vs. dynamic loading

Human mesenchymal stem cells (hMSCs) are capable of self-renewal and differentiation into various cell lineages. Mechanical stimuli have been shown to regulate function of stem cells through alteration in morphology and structure. The aim of this study was to evaluate and compare effects of uniaxial static stretch and combined static-dynamic stretch on the orientation, regulation and cytoskeletal structure of hMSCs. Mean values of topological were calculated before and after loadings. Moreover, fractal dimension (FD) was employed to quantify alterations in shape complexity of the cells. Internal cytoskeletal structure of cells was observed by actin filament staining. Results demonstrated a statistically significant change in cell topology and FD due to 10% static-dynamic stretch after 24 h. Static stretch was not as influential as dynamic loading. Whereas for combined static-dynamic stretch systemic alignment of cells was detected, in the static test group local alignment of actin fibers was observed, although the entire cell network was not totally aligned in a specific direction. It was concluded that dynamic stretch leads to cytoskeletal alignment and repolarization of hMSCs, whereas static stretch does not. Under static stretch hMSCs proliferated more than under dynamic stretch. Results can be applied in tissue engineering when functionalization of stem cells is required.