Three-dimensional fabrication of cell-laden biodegradable poly(ethylene glycol-co-depsipeptide) hydrogels by visible light stereolithography
Stereolithography (SLA) holds great promise in the fabrication of cell-laden hydrogels with biomimetic complexity for use in tissue engineering and pharmaceutics. However, the availability of biodegradable photocrosslinkable hydrogel polymers for SLA is very limited. In this study, a water-soluble methacrylated poly(ethylene glycol-co-depsipeptide) was synthesized to yield a biodegradable photocrosslinkable macromer for SLA. Structural analysis confirmed the inclusion of biodegradable peptide and ester groups and photocrosslinkable methacrylate groups into the polymer backbone. The new macromer combined with the RGDS peptide was used for the SLA fabrication of hydrogels in the absence and the presence of cells. With the increasing light exposure time in SLA, the mechanical stiffness of the hydrogels increased from 3 ± 1 kPa to 38 ± 13 kPa. The total mass loss of the samples within 7 days in PBS was 13–21% and within 24 days was 35–66%. Due to degradation, the mechanical stiffness decreased by one order magnitude within 7-day incubation in PBS. Encapsulated endothelial cells proliferated in the hydrogels during the 10-day in vitro cell culturing study. The macromer was further used in SLA to fabricate bifurcating tubular structures as preliminary vessel grafts. The new biodegradable, photocrosslinkable polymer is a significant addition to the very limited material selection currently available for the SLA-based additive manufacturing of cell-laden tissue engineering constructs.