Differential regulation of morphology and stemness of mouse embryonic stem cells by substrate stiffness and topography

Abstract

a b s t r a c tThe maintenance of stem cell pluripotency or stemness is crucial to embryonic development and differentiation. The mechanical or physical microenvironment of stem cells, which includes extracellular matrix stiffness and topography, regulates cell morphology and stemness. Although a growing body of evidence has shown the importance of these factors in stem cell differentiation, the impact of these biophysical or biomechanical regulators remains insufficiently characterized. In the present study, we applied a micro-fabricated polyacrylamide hydrogel substrate with two elasticities and three topographies to systematically test the morphology, proliferation, and stemness of mESCs. The independent or combined impact of the two factors on specific cell functions was analyzed. Cells are able to grow effectively on both polystyrene and polyacrylamide substrates in the absence of feeder cells. Substrate stiffness is predominant in preserving stemness by enhancing Oct-4 and Nanog expression on a soft polyacrylamide substrate. Topography is also a critical factor for manipulating stemness via the formation of a relatively flattened colony on a groove or pillar substrate and a spheroid colony on a hexagonal substrate. Although topography is less effective on soft substrates, it plays a role in retaining cell stemness on stiff, hexagonal or pillar-shaped substrates. mESCs also form, in a timely manner, a 3D structure on groove or hexagonal substrates. These results further the understanding of stem cell morphology and stemness in a microenvironment that mimics physiological conditions.

Microgravity, Stem Cells, and Embryonic Development: Challenges and Opportunities for 3D Tissue Generation

“…Intriguingly, the stronger mechanical forces exerted at the convex than at the concave edges are critical for steering MSCs toward the osteogenic fate (Ruiz and Chen, 2008). Substrate stiffness is also important in steering MSCs fate (Engler et al, 2006), and recent evidence indicates its involvement with 3D topography in controlling the stemness of ES cells (Lü et al, 2014). These data suggest that tensile gradients may operate as mechanical morphogens.…”

Mechanical forces direct stem cell behaviour in development and regeneration

“…The differentiation state of microtissues derived from ES cells increases with the stiffness and viscosity of the cell aggregate, which is regulated by actomyosin contractility. 99 Soft collagen-coated polyacrylamide 2D substrates that matched the intrinsic softness of ES cells maintained their pluripotency, 100 whereas localized stresses externally applied to the surface of ES cells by RGD ligand-coated magnetic beads induced ES cell spreading and differentiation. 101 The responses were correlated with the intrinsic softness of the cell, 101 probably by regulating actomyosin contractility.…”

Proliferation and stemness preservation of human adipose-derived stem cells by surface-modified in situ TiO2 nanofibrous surfaces

“…47 The resulting cascade reactions modulate gene expression and signal transduction, which are responsible for the upregulation of cell stemness. 49,50 However, the underlying mechanism of the cascade reaction in regulating the cell stemness is not entirely understood and remains to be elucidated.…”