Stem Cell Mechanosensation on Gelatin Methacryloyl (GelMA) Stiffness Gradient Hydrogels

Abstract

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.

Gradient Hydrogels—The State of the Art in Preparation Methods

“…Another procedure for the control of UV-initiated gelation was published by Kim et al [14]. A linear stiffness gradient in hydrogels based on gelatin methacryloyl was formed with the aid of photomasks that limited the penetration of UV light; thereby, different degrees of polymerization were initiated in the gelling material.…”

Matrix stiffness-sensitive long noncoding RNA NEAT1 seeded paraspeckles in cancer cells

“…Several markers including YAP/TAZ and MRTF-A, which shuffle between the nucleus and cytoplasm, and lamin A, have been described as being “mechanosensitive.” These markers respond differently depending on the stiffness of substrate that cells are cultured on ( Hadden et al. , 2017 ; Kim et al. , 2019 ; Major et al.…”

Advances of Stem Cell-Laden Hydrogels With Biomimetic Microenvironment for Osteochondral Repair

“…With this understanding, development of stiffness hydrogels is useful for researching the mechanical interactions between stem cells and extracellular environments. For example, Kim et al developed a linear stiffness gradient hydrogel via tailoring the polymerization of gelatin methacryloyl (GelMA) with a gradient UV photomask for stem cell mechano-sensation and differentiation abilities (Figure 1; Kim et al, 2020). Furthermore, they also found human adipose-derived stem cells (hADSCs) could increase chondrogenic roles in vivo by controlling the stiffness of cell-free and cell-embedded fibrin hydrogel; in this case, optimal scaffolds could promote both cell survival and chondrogenic potential for cartilage tissue engineering (Jung et al, 2010).…”