UC Riverside

Mechanotransduction is a process in which cells convert mechanical stimuli into a cellular response to compensate to a dynamically changing mechano-microenvironment. The stem cell niche isn’t constant, during morphogenesis various dynamic mechanical cues lead to the subsequent differentiation of germ layer specific cells, resulting in the development of specific tissues. When muscular movement is restricted in embryos, they are unable to make any movement needed for muscle development leading to issues in skeletal development. This demonstrates that the dynamic physical microenvironment is integral in embryonic development in driving lineage commitment to regulate tissue morphogenesis. In this regard, the current work focused on examining the effects of the physical mechano-microenvironment, using electrospun scaffolds and developing a dynamic magneto-modulated hydrogel, to examine the cellular behaviors of human induced pluripotent stem cells (iPSCs). We examined the effects of the physical mechano-microenvironment on (1) Rho-ROCK-YAP signaling as well as (2) directed multilineage differentiation. By culturing iPSCs on electrospun nanofibrous scaffolds, three-dimensional (3D) colonies are able to form where the spatially localized activity of Rho-ROCK signaling leads to the activation of Yes-associated-protein (YAP) which leads to the subsequent epigenetic histone marker expression. We further demonstrate that the activation of ROCK in iPSCs under differentiation condition causes more mesendodermal expression on outer layers of colonies while ectodermal markers are localized inside the colonies. Finally, we demonstrate that the mechano-modulation of scaffold stiffness leads to activation of Rho-ROCK signaling under higher stiffness while analyzing how anisotropic stiffness affects iPSC cell morphology as well as enhancing lineage specific differentiation of iPSCs. Overall, these findings demonstrate the integral role that Rho-ROCK-YAP signaling plays in mechanotransduction and how the physical niche of stem cells can be manipulated to better control iPSC colony morphology and differentiation efficiency to best mimic in vivo human gastrulation. We also demonstrate that our magneto-responsive hydrogel has dynamic capabilities that can be utilized towards more specified tissue morphogenesis and for further studies of iPSC behavior in response to the changing physical microenvironment.