Microstructure, local viscoelasticity and cell culture suitability of 3D hybrid HA/collagen scaffolds

Abstract

As mechanical properties of cell culture substrates matter, methods for mechanical characterization of scaffolds on a relevant length scale are required. We used multiple particle tracking microrheology to close the gap between elasticity determined from bulk measurements and elastic properties sensed by cells. Structure and elasticity of macroporous, three-dimensional cryogel scaffolds from mixtures of hyaluronic acid (HA) and collagen (Coll) were characterized. Both one-component gels formed homogeneous networks, whereas hybrid gels were heterogeneous in terms of elasticity. Most strikingly, local elastic moduli were significantly lower than bulk moduli presumably due to non-equilibrium chain conformations between crosslinks. This was more pronounced in Coll and hybrid gels than in pure HA gels. Local elastic moduli were similar for all gels, irrespective of their different swelling ratio and bulk moduli. Fibroblast cell culture proved the biocompatibility of all investigated compositions. Coll containing gels enabled cell migration, adhesion and proliferation inside the gels.

Microrheology imaging of fiber suspensions – a case study for lyophilized collagen I in HCl solutions

“…It is only for chemically crosslinked Coll networks that such a comparison exists. 41 In that latter study, local elastic moduli of Coll cryogels determined from MPT measurements were much lower than the corresponding bulk shear moduli. Analogous to earlier investigations on intermediate filament networks, 42 this was attributed to a pronounced contribution of stretched, out of equilibrium chain segments between network junctions or to densely crosslinked areas not accessible to the tracer particles, thus not contributing to the MPT modulus, but showing up in the bulk modulus.…”

The Overview of Porous, Bioactive Scaffolds as Instructive Biomaterials for Tissue Regeneration and Their Clinical Translation

“…Nonetheless, Wernike et al [ 170 ] demonstrated that cyclic loadings can help chondrocytes seeded into a polyurethane scaffold to maintain their phenotype as assessed by type II collagen measurement for short term culture, despite the fact that hypoxia seemed to be more efficient to prevent chondrocyte de-differentiation. While many studies were focused on the macroscopic level of Young’s modulus (i.e., of the whole material), cells interact only with their surroundings whose local Young’s modulus value can sometimes be smaller than the one of the bulk material [ 171 ]. Nonetheless, Grier et al [ 172 ] showed that tenocytes are sensitive to the way that collagen-GAG scaffold resisted to contractile forces of cells.…”

Precision 3D‐Printed Cell Scaffolds Mimicking Native Tissue Composition and Mechanics

“…This finding is in accordance to Roether et al, who described significantly lower local elasticities of proteinaceous, cryogelated scaffolds in comparison to the bulk modulus. [64] Figure 2. Generation of biocompatible high-precision 3D printed cell scaffolds.…”

“…Observing deviations of protein-based scaffold mechanics over time can reveal information about the aging of cross-linked hydrogels and can, therefore, indicate degradation processes or swelling. [64] This is especially important to consider when conducting cell experiments over several days or weeks. BSA-RB scaffolds stored in cell culture conditions were stable, while a softening was observed when stored in PBS at 4°C (Figure 4A).…”