Injectable Multi-Arm Poly(ethylene glycol)/Hyaluronic Acid Hydrogels for Adipose Tissue Engineering

Injectable hybrid hydrogels were cross-linked multi-arm amino-terminated poly(ethylene glycol) (PEG) with aldehyde hyaluronic acid (HA) upon mixing, without the addition of a chemical crosslinking agent. The gelation is attributed to the Schiff-base reaction between amino and aldehyde groups of PEG and oxidized HA. In the current work, 4-arm and 8-arm amino-terminated PEG crosslinked with aldehyde HA were characterized. In vitro gelation time, morphologies, swelling ratio, weight loss and compressive modulus of multi-arm PEG/HA hydrogels in phosphate buffered saline at 37°C were studied. Results demonstrated that the 4-arm PEG/HA hydrogel showed a faster gelation time, higher water uptake and lower weight loss comparing to the 8-arm PEG/HA hydrogel. Drug delivery results demonstrated that there was a significantly lower release of dexamethasone detected from the 4-arm PEG/HA hydrogel than the 8-arm PEG/HA hydrogel. Human adipose-derived stem cells were seeded into the 4-arm and 8-arm PEG/HA hydrogels in vitro to assess the biological performance and applicability of the gels as cell carriers. The 4-arm PEG hydrogel resulted in significantly enhanced cell adhesion and proliferation as compared to the 8-arm PEG hydrogel. Overall, these characteristics provide a potential opportunity for hybrid multi-arm PEG/HA hydrogels as injectable scaffolds in adipose tissue engineering application.