Patterning Three-Dimensional Hydrogel Microenvironments Using Hyperbranched Polyglycerols for Independent Control of Mesh Size and Stiffness

Abstract

The extracellular matrix (ECM) is an environment rich with structural, mechanical, and molecular signals that can impact cell biology. Traditional approaches in hydrogel biomaterial design often rely on modifying the concentration of cross-linking groups to adjust mechanical properties. However, this strategy provides limited capacity to control additional important parameters in 3D cell culture such as microstructure and molecular diffusivity. Here we describe the use of multifunctional hyperbranched polyglycerols (HPGs) to manipulate the mechanical properties of polyethylene glycol (PEG) hydrogels while not altering biomolecule diffusion. This strategy also provides the ability to separately regulate spatial and temporal distribution of biomolecules tethered within the hydrogel. The functionalized HPGs used here can also react through a copper-free click chemistry, allowing for the encapsulation of cells and covalently tethered biomolecules within the hydrogel. Because of the hyperbranched architecture and unique properties of HPGs, their addition into PEG hydrogels affords opportunities to locally alter hydrogel crosslinking density with minimal effects on global network architecture. Additionally, photocoupling chemistry allows micropatterning of bioactive cues within the three-dimensional gel structure. This approach therefore enables us to tailor mechanical and diffusive properties independently while further allowing for local modulation of biomolecular cues to create increasingly complex cell culture microenvironments.

Mesenchymal stromal cell remodeling of a gelatin hydrogel microenvironment defines an artificial hematopoietic stem cell niche

“…27, 2018; displayed two subsets of diffusion and mesh size. Notably, based on previous result from Mahadik et al [29] the poor diffusivity of the High hydrogel suggests an autocrine-dominated regime for HSC culture characterized by a small radius of cell-secreted chemical diffusion [92].…”

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

“…Unlike traditional dendrimers with precise molecular weight and well‐defined shape, which are synthesized via sequential generation of branches, identified by the number of “generations”, hyperbranched polymers are developed by one‐pot polymerization of monomers that generate random branching points, offering a more scalable and practical route for creating branched, multivalent macromolecules . Among them, HPG has garnered significant interest in the area of biomedical engineering, for their hydrophilicity and biocompatibility as well as their facile fabrication scheme (i.e., HPG is generally considered a branched poly(ethylene glycol) due to their polyoxyether backbone) . In addition, their multivalent hydroxyl groups provide an avenue for chemical modification to impart desired functionalities.…”

The role of pregnancy-specific glycoproteins on trophoblast motility in three-dimensional gelatin hydrogels

“…The biophysical properties of GelMA, including stiffness and crosslinking density, can be tuned by manipulating the degree of methacrylamide functionalization along the gelatin macromer during GelMA synthesis or via crosslinking intensity (Gilchrist et al, 2019b;Loessner et al, 2016;Schuurman et al, 2013;Yue et al, 2015;Zambuto et al, 2019b). This makes the GelMA system amenable to creating libraries of monolithic environments or spatially-graded hydrogels containing a linear gradient of embossed stiffness or matrix-bound proteins to locally influence cell behavior (Gilchrist et al, 2019b;Mahadik et al, 2015;Pedron et al, 2017). Other groups have used microfabrication techniques such as photopatterning, micromolding, self-assembly, and 3D printing to further customize the three-dimensional environment (Schuurman et al, 2013;Yue et al, 2015).…”