3D-architectured hydrogels guide regeneration of critically sized bone defects

The design principle for ArcGels was going beyond compromises in multifunctionality. The complex requirements for functions were realized by a hierarchical organization of the hydrogel, in which different functions were implemented at different levels. The multifunctional material is build up only from amino acids, with the material being synthesized and shaped in an integrated one-step procedure.

The molecular level is associated to cell adhesion and hydrolytic degradability, the level of pore walls relates to local mechanics and tension of polymer chains, while the porous architecture enables cell invasion, form stability, and shape recovery. The macroscopic level is related to the elastic recoverability with a defined compression module. The implementation of the functions on different levels enables adjusting of local elasticities independently from macroscopic mechanical properties.

Furthermore, ArcGels show a water-induced shape-memory effect. The ArcGels display a unique degradation profile with pore size growth similar to merging soap bubbles during the course of hydrolytic degradation while ensuring material integrity. Implanted in a critical bone defect in a rat model, a comparable healing capacity induced by an ArcGel to that of the clinical standard, cancellous bone graft was observed. It is remarkable that a rapidly degrading material can induce such an osteoinductive effect.