The maintenance of stem cell pluripotency or sternness 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 sternness 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 sternness 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 sternness 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. (C) 2014 Elsevier Ltd. All rights reserved.

[http://dx.doi.org/10.1016/j.biomaterials.2014.01.066]
This work was supported by National Key Basic Research Foundation of China grant 2011CB710904, National Natural Science Foundation of China grant 31110103918 and 31000421, Strategic Priority Research Program grant XDA01030102, National High Technology Research and Development Program of China grant 2011AA020109.

The article was published as:
Lv DY,Luo CH,Zhang C,et al. Differential Regulation Of Morphology And Stemness Of Mouse Embryonic Stem Cells By Substrate Stiffness And Topography.Biomaterials,2014,35(13):3945-3955.