Impact of substrate adhesiveness on embryonic stem cell pluripotency

GOAL: We developed novel hydrogel substrates for stem cell culture, in which we independently vary substrate stiffness and adhesiveness. Substrate adhesiveness is here defined by the density of matrix tethering sites on the hydrogel surface (not by protein concentration). Any extra-cellular matrix protein can be covalently bonded to the gel at those tethering sites. The density of matrix tethering sites is controlled by the concentration of a co-factor added to the polyacrylamide hydrogel premix. The goal of this study was to assess the impact of varying matrix tethering on the gene expression of pluripotent embryonic stem cells, and to determine whether the potential effect would be dependent on substrate stiffness. 6 different conditions were used: 2 stiffnesses "SOFT" and "STIFF" (E~750Pa and E~160kPa respectively) 3 adhesiveness conditions corresponding to LOW (16mM), MID (48mM) and HIGH (80mM) concentrations of the AHA co-factor.