Subchondral bone-inspired hydrogel scaffold for cartilage regeneration

Promoting the in situ regeneration of cartilage without additional cells or cytokines remains challenging. Here, inspired by the unique microstructures of subchondral bone, a cell and cytokine free hydrogel scaffold for cartilage regeneration was developed via a strategy of directional lyophilization and postcrosslinking. This strategy achieved intersecting microchannels in an orderly arrangement and an aligned ladder-like texture in a semi-interpenetrating hydrogel network. The resulting hydrogel had similar mechanical properties to the native cartilage extracellular matrix. Incorporating chitosan into the rigid network also endowed the hydrogel with excellent hemostatic properties. By delicately tuning the components and postcrosslinking conditions, the hydrogel was further endowed with suitable swelling and degradation properties for cartilage regeneration. In vitro tests showed that the highly biocompatible hydrogel scaffold could facilitate the migration and chondrogenic differentiation of bone marrow mesenchymal stem cells. In vivo results further verified that the hydrogel could promote the in situ regeneration of cartilage in a rat model of osteochondral defects. In summary, the subchondral bone-like hydrogel revealed promising prospects in cartilage regeneration and a variety of bioremediation applications.