Comprehensive Examination of Mechanical and Diffusional Effects on Cell Behavior Using a Decoupled 3D Hydrogel System

Abstract

Hydrogels possess several physical and chemical properties suitable for engineering cellular environments for biomedical applications. Despite recent advances in hydrogel systems for cell culture, it is still a significant challenge to independently control the mechanical and diffusional properties of hydrogels, both of which are well known to influence various cell behaviors when using hydrogels as 3D cell culture systems. Controlling the crosslinking density of a hydrogel system to tune the mechanical properties inevitably affects their diffusional properties, as the crosslinking density and diffusion are often inversely correlated. In this study, a polymeric crosslinker is demonstrated that allows for the adjustment of the degree of substitution of reactive functional groups. By using this polymeric crosslinker, the rigidity of the resulting hydrogel is controlled in a wide range without changing the polymer concentration. Furthermore, their diffusional properties, as characterized by their swelling ratios, pore diameters, and drug release rates, are not significantly affected by the changes in the degree of substitution. 3D cell studies using this hydrogel system successfully demonstrate the varying effects of mechanical properties on different cell types, whereas those in a conventional hydrogel system are more significantly influenced by changes in diffusional properties.

Complex Tuning of Physical Properties of Hyperbranched Polyglycerol‐Based Bioink for Microfabrication of Cell‐Laden Hydrogels

“…However, the effect of mechanical properties of hydrogel on the proliferation was more dependent on the cell type. For MSCs, the proliferation was biphasic; the proliferation rate ( k P ) was greater at the lower DS (DS1) and the higher DS (DS3), and lower at intermediate DS (DS2) and the highest DS (DS4) (Figure c,d) . The greater proliferation at lower acrylate DS (DS1) was likely attributed to the increased media perfusion and availability of space, while increased mechanical rigidity at higher acrylate DS (DS3) promoted the proliferation via mechanotransduction despite lower permeability of hydrogel.…”

“…The monomers used for this study were PEGMA ( M n 500, Sigma Aldrich), acrylamide (Sigma Aldrich), and MGel. The detailed synthesis and characterization of MGel are provided in the Supporting Information (see Figure S9, Supporting Information) . For PEGMA and acrylamide, their concentrations were either 10 or 20%, while varying the AHPG concentration from 1 to 5%.…”

“…Mechanical Properties of AHPG‐Linked Hydrogels : The elastic moduli of AHPG‐linked hydrogels were calculated from stress–strain relationships obtained from uniaxial compression (Model 3343, Instron) . Briefly, a hydrogel disk was compressed at a rate of 1 mm min −1 , and the elastic modulus was calculated as the slope of the stress–strain curve at the initial 10% strain, where the curve remained linear (i.e., elastic region).…”

Microfluidics‐Assisted Fabrication of Microtissues with Tunable Physical Properties for Developing an In Vitro Multiplex Tissue Model

“…Synthesis of Photo‐Crosslinkable Gelatin : Conjugation of methacrylic functional group to gelatin (i.e., MGel) was accomplished following a previously published report . Briefly, gelatin (10 g, from porcine skin, Sigma Aldrich), 4‐dimethylaminopyridine (1 g, Sigma Alrdich), and 4‐methoxyphenol (0.1 g, Sigma Alrdich) were first dissolved in 100 mL dimethyl sulfoxide at 50 °C.…”

“…The mechanical properties of MGel hydrogels were assessed by measuring elastic moduli from uniaxial compression tests (Model 3343, Instron) . Each hydrogel disk was compressed at a fixed rate (1 mm min −1 ), and a stress–strain relationship was obtained.…”