Adv. Funct. Mater. 2022, 32, 2200710



 Osteochondral tissue exhibits multiple morphological gradients from cartilage to subchondral bone in terms of cell, composition, structure and mechanical properties. This gradient organization is formed during development. Regeneration of osteochondral tissue remains challenging due to differential tissue arrangement and anisotropic physiological features. Therefore, it is of great significance to develop a heterogeneous structure with both biomechanical and biochemical gradients to simulate the osteochondral microenvironment and achieve simultaneous regeneration of cartilage and subchondral bone. Overall, the development of bioinks for 3D bioprinting of heterogeneous structures, while obtaining satisfied biomechanical and biochemical gradients, is essential for osteochondral regeneration.

In this paper, the joint team of Professor Ao Yingfang and Professor CAI Qing developed a novel dual-network host-guest hydrogel bioink composed of dopamine-modified GelMA (GELMA-DA), GelMA and acrylate β-cyclodextrin (AC-β-CD). Ac-β-cd and dopamine side groups can form host-guest complexes to act as dynamic cross-linking bonds, endowing hydrogels with excellent toughness and elasticity, while the mechanical strength of hydrogels is enhanced by the polymerization of ethylene groups. It is feasible to construct osteochondral structures with mechanical gradients by adjusting the concentration of ethylene polymer. In addition, excess AC-β-CD can be used to encapsulate bioactive drugs for sustained long-term release. The carried stem cells can freely diffuse and migrate in the hydrogel network, and secrete different collagens under the guidance of the continuous release of MLT/KGN in the local microenvironment, which provides the power to complete the deposition of layered ECM and osteochondral arrangement, and finally realize the full-thickness osteochondral regeneration.