Stem Cell Mechanosensation on Gelatin Methacryloyl (GelMA) Stiffness Gradient Hydrogels
Stiffness gradient hydrogels are a useful platform for studying mechanical interactions between cells and their surrounding environments. Here, we developed linear stiffness gradient hydrogels by controlling the polymerization of gelatin methacryloyl (GelMA) via differential UV penetration with a gradient photomask. Based on previous observations, a stiffness gradient GelMA hydrogel was created ranging from ~ 4 to 13 kPa over 15 mm (0.68 kPa/mm), covering the range of physiological tissue stiffness from fat to muscle, thereby allowing us to study stem cell mechanosensation and differentiation. Adipose-derived stem cells on these gradient hydrogels showed no durotaxis, which allowed for the screening of mechanomarker expression without confounding directed migration effects. In terms of morphological markers, the cell aspect ratio showed a clear positive correlation to the underlying substrate stiffness, while no significant correlation was found in cell size, nuclear size, or nuclear aspect ratio. Conversely, expression of mechanomarkers (i.e., Lamin A, YAP, and MRTFa) all showed a highly significant correlation to stiffness, which could be disrupted via inhibition of non-muscle myosin or Rho/ROCK signalling. Furthermore, we showed that cells plated on stiffer regions became stiffer themselves, and that stem cells showed stiffness-dependent differentiation to fat or muscle as has been previously reported in the literature.
KeywordsMechanosensitive Stiffness Gradient Stem cell Differentiation
This study work was supported by National Health and Medical Research Council Grant PG1098449 (to YSC), Heart Foundation Future Leader Fellowship 101173 (to YSC), Department of Health, Western Australia, Merit awards—Project and fellowship (to YSC), and Universities Australia DAAD German Research Cooperation 5744610 (to YSC, CK, AWH, JLY and JPS).
CK, LGM and YSC designed and planned the study. JLY, AWH, and JPS performed SEM and pore size analysis. KJ and ZMA performed Raman spectroscopy. JHJ, YH and DWH synthesized GelMA. CK, JLY and YSC drafted the manuscript. YSC provided supervision and funding. All authors discussed the data and contributed to the final version of the manuscript.
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