Hierarchically designed injectable hydrogel from oxidized dextran, amino gelatin and 4-arm poly(ethylene glycol)-acrylate for tissue engineering application

Abstract

Hydrogels are high in water content and have physical properties similar to native extracellular matrix (ECM), and thus they have been widely studied as three-dimensional (3D) tissue engineering scaffolds for cell culture. In this work, a two-step process was introduced to fabricate injectable hydrogel from oxidized dextran (ODex), amino gelatin (MGel) and 4-arm poly(ethylene glycol)-acrylate (4A-PEG-Acr) for cell encapsulation. A primary network was formed based on a Schiff based reaction between ODex and MGel, then a UV light-induced radical reaction of 4A-PEG-Acr was used to produce the independent secondary network. Both of the reactions were carried out under physiological conditions in the presence of living cells with no toxicity. The primary network depending on natural polymers could degrade rapidly to provide space and nutrition for encapsulated cells’ growth, and the secondary network could provide long-term mechanical stability. The attachment and spreading of pre-osteoblasts (MC3T3-E1) on IPN hydrogels were observed by DEAD/LIVE kit staining. Furthermore, cell spreading and cell proliferation within IPN hydrogels were observed using confocal microscopy after phalloidin/DAPI staining. The results showed that the as-prepared interpenetrating polymer network (IPN) hydrogels possessed good mechanical properties, a controllable degradation rate and favorable biocompatibility. Therefore, the hierarchically designed hydrogel in this study could be a promising candidate for bone or cartilage tissue engineering applications.