Recent studies have found discordant mechanosensitive outcomes when comparing 2D and 3D, highlighting the need for tools to study mechanotransduction in 3D across a wide spectrum of stiffness. A gelatin methacryloyl (GelMA) hydrogel with a continuous stiffness gradient ranging from 5 to 38 kPa was developed to recapitulate physiological stiffness conditions. Adipose-derived stem cells (ASCs) were encapsulated in this hydrogel, and their morphological characteristics and expression of both mechanosensitive proteins (Lamin A, YAP, and MRTFa) and differentiation markers (PPARγand RUNX2) were analyzed. Low-stiffness regions (âˆ¼8 kPa) permitted increased cellular and nuclear volume and enhanced mechanosensitive protein localization in the nucleus. This trend was reversed in high stiffness regions (âˆ¼30 kPa), where decreased cellular and nuclear volumes and reduced mechanosensitive protein nuclear localization were observed. Interestingly, cells in soft regions exhibited enhanced osteogenic RUNX2 expression, while those in stiff regions upregulated the adipogenic regulator PPARÎ³, suggesting that volume, not substrate stiffness, is sufficient to drive 3D stem cell differentiation. Inhibition of myosin II (Blebbistatin) and ROCK (Y-27632), both key drivers of actomyosin contractility, resulted in reduced cell volume, especially in low-stiffness regions, causing a decorrelation between volume expansion and mechanosensitive protein localization. Constitutively active and inactive forms of the canonical downstream mechanotransduction effector TAZ were stably transfected into ASCs. Activated TAZ resulted in higher cellular volume despite increasing stiffness and a consistent, stiffness-independent translocation of YAP and MRTFa into the nucleus. Thus, volume adaptation as a function of 3D matrix stiffness can control stem cell mechanotransduction and differentiation.
|Number of pages||11|
|Journal||ACS Applied Materials and Interfaces|
|Publication status||Published - 2019 Dec 11|
Bibliographical noteFunding Information:
L.G.M., A.W.H., and J.L.Y. contributed equally to this work. L.G.M., A.W.H., J.L.Y., and YS.C. designed and planned the study. J.L.Y., A.W.H., and J.P.S. performed SEM and pore size analysis. M.S.H., R.W.S., and B.F.K. performed OCE and stress relaxation analysis. K.J. and Z.M.A. performed Raman spectroscopy. J.H.J., Y.H., and D.-W.H. synthesized GelMA. H.W.P. and K-L. G. generated TAZ overexpressed cells. L.G.M., A.W.H., J.L.Y., and YS.C. drafted the manuscript. Y.S.C provided supervision and funding. This study work was supported by National Health and Medical Research Council Grant PG1098449 (to Y.S.C and K.-L.G), Heart Foundation Future Leader Fellowship 101173 (to Y.S.C), Department of Health, Western Australia, Merit awards–project and fellowship (to Y.S.C), Universities Australia DAAD German Research Cooperation 5744610 (to Y.S.C, I.L.C, A.W.H, J.L.Y, and J.P.S), and UWA RIGG (to Y.S.C and HW.P). The authors declare no competing financial interest.
© 2019 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)