Injectable and Degradable Poly(Oligoethylene glycol methacrylate) Hydrogels with Tunable Charge Densities as Adhesive Peptide-Free Cell Scaffolds

Injectable, dual-responsive, and degradable poly(oligo ethylene glycol methacrylate) (POEGMA) hydrogels are demonstrated to offer potential for cell delivery. Charged groups were incorporated into hydrazide and aldehyde-functionalized thermoresponsive POEGMA gel precursor polymers via the copolymerization of N,N'-dimethylaminoethyl methacrylate (DMAEMA) or acrylic acid (AA) to create dual-temperature/pH-responsive in situ gelling hydrogels that can be injected via narrow gauge needles. The incorporation of charge significantly broadens the swelling, degradation, and rheological profiles achievable with injectable POEGMA hydrogels without significantly increasing nonspecific protein adsorption or chronic inflammatory responses following in vivo subcutaneous injection. However, significantly different cell responses are observed upon charge incorporation, with charged gels significantly improving 3T3 mouse fibroblast cell adhesion in 2D and successfully delivering viable and proliferating ARPE-19 human retinal epithelial cells via an "all-synthetic" matrix that does not require the incorporation of cell-adhesive peptides.