Adipose Tissue-Derived Stromal Cells Alter the Mechanical Stability and Viscoelastic Properties of Gelatine Methacryloyl Hydrogels

Abstract

The extracellular matrix provides mechanical cues to cells within it, not just in terms of stiffness (elasticity) but also time-dependent responses to deformation (viscoelasticity). In this work, we determined the viscoelastic transformation of gelatine methacryloyl (GelMA) hydrogels caused by adipose tissue-derived stromal cells (ASCs) through mathematical modelling. GelMA-ASCs combination is of interest to model stem cell-driven repair and to understand cell-biomaterial interactions in 3D environments. Immortalised human ASCs were embedded in 5%, 10%, and 15% (w/v) GelMA hydrogels and evaluated for 14 d. GelMA had a concentration-dependent increase in stiffness, but cells decreased this stiffness over time, across concentrations. Viscoelastic changes in terms of stress relaxation increased progressively in 5% GelMA, while mathematical Maxwell analysis showed that the relative importance (Ri) of the fastest Maxwell elements increased proportionally. The 10% GelMA only showed differences at 7 d. In contrast, ASCs in 15% GelMA caused slower stress relaxation, increasing the Ri of the slowest Maxwell element. We conclude that GelMA concentration influenced the stiffness and number of Maxwell elements. ASCs changed the percentage stress relaxation and Ri of Maxwell elements transforming hydrogel viscoelasticity into a more fluid environment over time. Overall, 5% GelMA induced the most favourable ASC response.

Matrix Metalloproteases from Adipose Tissue-Derived Stromal Cells Are Spatiotemporally Regulated by Hydrogel Mechanics in a 3D Microenvironment

“…The expression of matrix metalloproteases (MMPs), among other enzymes, enable cells to degrade their surrounding environment, facilitating their spreading, migration, or proliferation, among others [ 40 ]. ASCs can alter the stiffness and viscoelasticity of GelMA hydrogels [ 41 ] through elusive mechanisms; however, this might relate to a combination of MMPs’ degradation and matrix deposition.…”

An in vitro model of fibrosis using crosslinked native extracellular matrix-derived hydrogels to modulate biomechanics without changing composition

“…Cell viability of the MRC-5 cells cultured on LdECM and Ru-LdECM hydrogels was assessed after 1 and 7 days using Calcein AM (Thermo Scientific, Breda, the Netherlands) to stain live cells and propidium iodide (PI; Sigma-Aldrich) for staining dead cells, as previously described. 30 The hydrogels were first washed with HBSS and then incubated with serum free media containing 5 µM Calcein AM and 2 µM PI, for 1 hour at 37°C. After incubation, fluorescent images were captured using a EVOS Cell Imaging System (Thermo Scientific) with GFP (509 nm) and Texas Red (615 nm) channels.…”

Molecular Morphology and Function of Stromal Cells

“…In the field of tissue engineering for regenerative-medicine purposes, Martinez-Garcia and colleagues [8] investigated the combination of gelatine methacryloyl hydrogels and ASCs to model stem cell-driven repair and to understand cell-biomaterial interactions in 3D environments. Indeed, within a 3D environment, stromal cells experience biochemical and biomechanical stimuli, with the extracellular matrix regulating cellular behavior via activation of intracellular signaling pathways and, in response, cells degrade, de-posit, and rearrange matrix components.…”

“…Indeed, within a 3D environment, stromal cells experience biochemical and biomechanical stimuli, with the extracellular matrix regulating cellular behavior via activation of intracellular signaling pathways and, in response, cells degrade, de-posit, and rearrange matrix components. The authors found that ASCs transform gelatine methacryloyl hydrogel viscoelasticity into a more fluid environment and alter the hydrogel mechanical stability [8]. In addition, out of the concentrations studied, 5% gelatine methacryloyl hydrogel provided the most conducive biomechanical environment for ASCs to spread and remain viable [8].…”

“…The authors found that ASCs transform gelatine methacryloyl hydrogel viscoelasticity into a more fluid environment and alter the hydrogel mechanical stability [8]. In addition, out of the concentrations studied, 5% gelatine methacryloyl hydrogel provided the most conducive biomechanical environment for ASCs to spread and remain viable [8].…”