Constitutive modeling of compressible type-I collagen hydrogels

Abstract

Collagen hydrogels have been used ubiquitously as engineering biomaterials with a biphasic network of fibrillar collagen and aqueous-filled voids that contribute to a complex, compressible, and nonlinear mechanical behavior - not well captured within the infinitesimal strain theory. In this study, type-I collagen, processed from a bovine corium, was fabricated into disks at 2, 3, and 4% (w/w) and exposed to 0, 10, 10, and 10 microjoules of ultraviolet light or enzymatic degradation via matrix metalloproteinase-2. Fully hydrated gels were subjected to unconfined, aqueous, compression testing with experimental data modeled within a continuum mechanics framework by employing the uncommon Blatz-Ko material model for porous elastic materials and a nonlinear form of the Poisson's ratio. From the Generalized form, the Special Blatz-Ko, compressible Neo-Hookean, and incompressible Mooney-Rivlin models were derived and the best-fit material parameters reported for each. The average root-mean-squared (RMS) error for the General (RMS = 0.13 ± 0.07) and Special Blatz-Ko (RMS = 0.13 ± 0.07) were lower than the Neo-Hookean (RMS = 0.23 ± 0.10) and Mooney-Rivlin (RMS = 0.18 ± 0.08) models. We conclude that, with a single fitted-parameter, the Special Blatz-Ko sufficiently captured the salient features of collagen hydrogel compression over most examined formulations and treatments.

Transforming Growth Factor Beta3 is Required for Cardiovascular Development

“…This supports the hypothesis that loss of Tgfb3 results in a compensatory TGFβ ECM response. This failure of reorganization is indicative of altered contractile machinery and/or adhesion molecules [33]. TGFB3 mutations have also been reported in patients with mitral and aortic valve disease and that hyper-activated TGFβ signaling has been implicated in mammalian valve disease [9,53].…”

“…Mouse fibroblasts were maintained in DMEM (Invitrogen) supplemented with 10% bovine serum, 5% fetal calf serum and 1% penicillin/streptomycin (Sigma-Aldrich, St. Louis, MO, USA) at 37 • C/5% CO2. In addition to reorganization, collagen contraction assays are indicative of the capacity for embedded cells to generate mechanical loads [33]. The capability of mouse fibroblasts to form lattices in collagen gels was assessed by plating 105 cells in 2mg/mL collagen type-I (in 18mM acetic acid) prepared in complete media and supplemented with 0.1 M NaOH, as detailed [34].…”

Tumour growth: Bayesian parameter calibration of a multiphase porous media model based on in vitro observations of Neuroblastoma spheroid growth in a hydrogel microenvironment

“…To better characterise the multiphase nature of hydrated materials (like the collagen hydrogels of these spheroids), poroelastic approaches are seen as the best solution [119]. In our porohyperelastic material model, the solid phase is assumed to have a Neo-Hookean formulation (although this model could be a future line to work in) [120]. The multiphase model presented here allows us to recreate the experimental setup, as the biophysical properties of the hydrogel scaffold (i.e., stiffness, porosity and permeability) can form valuable inputs in the model.…”

Cardiomyogenic Differentiation Potential of Human Dilated Myocardium-Derived Mesenchymal Stem/Stromal Cells: The Impact of HDAC Inhibitor SAHA and Biomimetic Matrices

“…Injectable collagen hydrogels [ 68 ], as well as decellularized intact heart tissue ECM [ 69 ], have been used to stabilize ventricle, limit adverse remodeling, and improve cardiac functioning after myocardial infarction in animal modelling systems. However, as heart is a highly physically loaded organ, the hydrogels used for the mechanical studies in vitro or implanted in vivo should withstand high compression and/or compaction [ 70 ]. As biological function of collagen lies predominantly in its mechanical properties, its use for the heart regeneration purposes is the most reliable [ 28 ].…”