Hydrogel based on interpenetrating polymer networks of dextran and gelatin for vascular tissue engineering

Hydrogel networks are highly desirable as three-dimensional (3-D) tissue engineering scaffolds for cell encapsulation due to the high water content and ability to mimick the native extracellular matrix. However, their application is limited by their nanometer-scale mesh size, which restricts the spreading and proliferation of encapsulated cells, and their poor mechanical properties. This study seeks to address both limitations through application of a novel cell-encapsulating hydrogel family based on the interpenetrating polymer network (IPN) of gelatin and dextran bifunctionalized with methacrylate (MA) and aldehyde (AD) (Dex–MA–AD). The chemical structure of the synthesized Dex–MA–AD was verified by 1H-NMR and the degrees of substitution of MA and AD were found to be 14 and 13.9 ± 1.3 respectively. The water contents in all these hydrogels were approximately 80%. Addition of 40 mg/ml to 60 mg/ml gelatin to neat Dex–MA–AD increased the compressive modulus from 15.4 ± 3.0 kPa to around 51.9 ± 0.1 kPa (about 3.4-fold). Further, our IPN hydrogels have higher dynamic storage moduli (i.e. on the order of 104 Pa) than polyethylene glycol-based hydrogels (around102–103 Pa) commonly used for smooth muscle cells (SMCs) encapsulation. Our dextran-based IPN hydrogels not only supported endothelial cells (ECs) adhesion and spreading on the surface, but also allowed encapsulated SMCs to proliferate and spread in the bulk interior of the hydrogel. These IPN hydrogels appear promising as 3-D scaffolds for vascular tissue engineering.