Anisotropic rigidity sensing on grating topography directs human mesenchymal stem cell elongation

Abstract

Through mechanotransduction, cells can sense physical cues from the extracellular environment and convert them into internal signals that affect various cellular functions. For example, human mesenchymal stem cells (hMSCs) cultured on topographical gratings have been shown to elongate and differentiate to different extents depending on grating width. Using a combination of experiments and mathematical modeling, the physical parameters of substrate topography that direct cell elongation were determined. On a variety of topographical gratings with different grating widths, heights and rigidity, elongation of hMSCs was measured and a monotonic increase was observed for grating aspect ratio (crosssectional height to line-width ratio) between 0.035 and 2. The elongation was also dependent on the grating substrate rigidity over a range of 0.18-1.43 MPa. A mathematical model was developed to explain our observations by relating cell elongation to the anisotropic deformation of the gratings and how this anisotropy depends on the aspect ratio and rigidity of the gratings. Our model was in good agreement with the experimental data for the range of grating aspect ratio and substrate rigidity studied. In addition, we also showed that the percentage of aligned cells, which had a strong linear correlation with elongation for slightly elongated cells, saturated toward 100 % at higher level of cell elongation. Our results may be useful in designing gratings to elicit specific cellular responses that may depend on the extent of cell elongation.

Enhanced differentiation of neural progenitor cells into neurons of the mesencephalic dopaminergic subtype on topographical patterns

“…The aspect ratio of the gratings was shown to be an important determinant of mesenchymal stem cell elongation and alignment [26,27]. Therefore, the spacing and height of the gratings play important roles in the topographical construct that determines cell behaviour and cell fate.…”

“…The elongation parameter E is calculated as the ratio of the long axis over the short axis on an approximated ellipse [26] by using ImageJ (NIH). The percentage of aligned cells was obtained by looking at the number of cells that had E > 3 and angle of the long axis and the grating <15 .…”

Deterministic control of mean alignment and elongation of neuron-like cells by grating geometry: a computational approach

“…1,[7][8][9][10] Moreover, the compliance of the underlying substrate is able to select between simultaneously growing neurons and astrocytes 11 (e.g., soft gels encouraged neurons and suppressed astrocytes), while its increase is also responsible for the enhancement (more than three times as much) of the branching ability of cells. 21 In this case, the aspect ratio of gratings and the anisotropic substrate rigidity were found to influence the behaviour of cells, while an experimental correlation was described between hMSC alignment and elongation. Indeed, from a side, neuron-like cells (PC12) 13 can reversibly adopt neuronal characteristics upon exposure to nerve growth factors and extend protrusions which are morphologically analogous to axons extending from primary sympathetic neurons.…”

Stem cells for tissue engineered vascular bypass grafts

“…Stem cell differentiation has been shown to be dependent on substrate rigidity and cell shape; it is therefore possible to use gratings with an optimal geometry to induce cell elongation that corresponds to a desired level of differentiation. A combination of experiments and mathematical modeling has been used to mechanistically understand how anisotropic rigidity directs cell elongation and alignment on gratings, leading to stem cell differentiation (Wong et al 2014). Based on experimental results, it was hypothesized that hMSCs sense the anisotropic rigidity on gratings, which acts as the driving force behind cell elongation.…”