Micropatterning of Poly(Ethylene Glycol) Diacrylate Hydrogels with Biomolecules to Regulate and Guide Endothelial Morphogenesis

Abstract

Angiogenesis, which is morphogenesis undertaken by endothelial cells (ECs) during new blood vessel formation, has been traditionally studied on natural extracellular matrix proteins. In this work, we aimed to regulate and guide angiogenesis on synthetic, bioactive poly(ethylene glycol)-diacrylate (PEGDA) hydrogels. PEGDA hydrogel is intrinsically cell nonadhesive and highly resistant to protein adsorption, allowing a high degree of control over presentation of ligands for cell adhesion and signaling. Since these materials are photopolymerizable, a variety of photolithographic technologies may be applied to spatially control presentation of bioactive ligands. To manipulate EC adhesion, migration, and tubulogenesis, the surface of PEGDA hydrogels was micropatterned with a cell adhesive ligand, Arg-Gly-Asp-Ser (RGDS), in desired concentrations and geometries. ECs cultured on these RGDS patterns reorganized their cell bodies into cord-like structures on 50-microm-wide stripes, but not on wider stripes, suggesting that EC morphogenesis can be regulated by geometrical cues. The cords formed by ECs were reminiscent of capillaries with cells participating in the self-assembly and reorganization into multicellular structures. Further, endothelial cord formation was stimulated on intermediate concentration of RGDS at 20 microg/cm(2), whereas it was inhibited at higher concentrations. This work has shown that angiogenic responses can be tightly regulated and guided by micropatterning of bioactive ligands and also demonstrated great potentials of micropatterned PEGDA hydrogels for various applications in tissue engineering, where vascularization prior to implantation is critical.

Emergence of collective modes and tri-dimensional structures from epithelial confinement

“…2D confinement at the cell scale has been previously evidenced to favour the formation of cysts in Matrigel 38 . Cord formation has also been observed for human umbilical vein endothelial cells on adherent stripes of width smaller than 50 mm in the absence of gel or other 3D environment 39 . Our own work confirms that geometrical cues are sufficient to trigger morphogenetic mechanisms at the very early stages of the formation of the organ itself.…”

Generation and Recovery of β-cell Spheroids From Step-growth PEG-peptide Hydrogels

“…While protease-sensitive peptides can be incorporated into PEG macromer backbone to render the otherwise inert PEGDA hydrogels sensitive to enzymatic cleavage, the conjugation often uses expensive reagents and the resulting networks still contain high degree of heterogeneity due to the nature of chain-growth polymerization. [13][14][15] controllable 3D microenvironment for investigating cell survival and activity, while the use of protease-sensitive peptide sequence provides a mild way for recovery of cell constructs formed naturally within hydrogels. In this protocol we utilize step-growth photopolymerized thiol-ene hydrogels fabricated using 4-arm PEG-norbornene (PEG4NB) and a chymotrypsin-sensitive peptide crosslinker (CGGY↓C) for the encapsulation of MIN6 β-cells.…”

Bioartificial matrices for therapeutic vascularization

“…PEG has a well-established chemistry and long history of safety in vivo. Addition of acrylate groups flanking the PEG chain allows for photo or chemical cross-linking of a PEGDA macromer solution, as well as incorporation of biomolecules such as protease-degradable sites, adhesive ligands, and growth factors (14)(15)(16). A major strength of this strategy is the modular "plugand-play" design of the base hydrogel system, which allows the tailoring of the biochemical and mechanical properties of the delivery vehicle.…”