Cell-laden alginate dialdehyde-gelatin hydrogels formed in 3D printed sacrificial gel.

Alginate dialdehyde-gelatin (ADA-GEL) hydrogels have been reported to be suitable matrices for cell encapsulation. In general, application of ADA-GEL as bioink has been limited to planar structures due to its low viscosity. In this work, ring shaped constructs of ADA-GEL hydrogel were fabricated by casting the hydrogel into sacrificial molds which were 3D printed from 9% methylcellulose and 5% gelatin. Dissolution of the supporting structure was observed during the 1 week of sample incubation. In addition, the effect of different crosslinkers (Ba and Ca) on the physicochemical properties of ADA-GEL and on the behavior of encapsulated MG-63 cells was investigated. It was found that Ba crosslinked network had more than twice higher storage modulus, and mass decrease to 70% during incubation compared to 42% in case of hydrogels crosslinked with Ca. In addition, faster increase in cell viability during incubation and earlier cell network formation were observed after Ba crosslinking. No negative effects on cell activity due to the use of sacrificial materials were observed. The approach presented here could be further developed for cell-laden ADA-GEL bioink printing into complex 3D structures.