Bioactive Poly(ethylene Glycol) Acrylate Hydrogels for Regenerative Engineering

Abstract

Poly(ethylene glycol) (PEG)-based hydrogels have been used in regenerative engineering applications due to attributes such as the ability to encapsulate cells, control the presentation of bioactive ligands, and manipulate the mechanical properties of the hydrogels. PEG chains are highly hydrophilic, uncharged and possess high chain mobility. This allows resistance to protein adsorption, making PEG very bioinert. Certain derivatives, such as PEG diacrylate (PEGDA), can be crosslinked to form hydrogels under conditions mild enough to allow cell encapsulations. PEGDA hydrogels can also be manipulated to span a range of stiffnesses relevant to soft tissues. Additionally, PEG chains can easily be covalently modified with peptides and proteins to allow cell adhesion or provide intrinsic cues to cells within the PEG hydrogel. Among the extensive uses of PEG acrylate-based hydrogels for regenerative engineering purposes, this review will first focus on the formation of bioactive PEG-acrylate hydrogels and then highlight tissue engineering applications of PEGDA-based hydrogels, with specific examples for cartilage tissue engineering, bone tissue engineering, vasculogenesis, liver tissue engineering, cardiac tissue engineering and the development of tumor models. Regenerative engineering seeks to combine materials with cells to generate new tissues outside of the body. In order to interact with cells and support the formation of tissues, the materials must be rendered biologically active and adopt certain characteristics of the native tissue environment. This review focuses on poly(ethylene glycol) (PEG) acrylate materials for regenerative engineering purposes. PEG acrylate-based materials are easily modified to be biologically active and are capable of mimicking a range of characteristics of the native tissue environment. These PEG materials have supported the formation cartilage tissues, bone tissues, blood vessels, liver tissues, cardiac tissues and tumor models. Future work will apply these results to the continued modifications of PEG-acrylate materials to generate more complex tissues. Specifically, the ability to mimic transient characteristics of native tissue microenvironments and the relevance of cell types in each tissue generated will need to be investagted within the PEG acylate materials.