Rapid Customization of Biomimetic Cartilage Scaffold with Stem Cell Capturing and Homing Capabilities for In Situ Inductive Regeneration of Osteochondral Defects.

3D printing of articular cartilage tissue faces challenges like replicating its complex structure, time‐consuming in vitro stem cell culture, and a lack of robust in situ regeneration methods for osteochondral defects (OC). In response, an innovative approach utilizing pre‐designed bioink modular units for one‐step printing and immediate implantation is proposed, circumventing the need for prior in vitro stem cell cultivation. The resulting printed scaffold not only accurately reproduces the three‐layer structure and material gradient of articular cartilage tissue but also attains impressive compressive strength (6.3 MPa) through the reinforcement of hydroxyapatite nanofibers and the establishment of chemical bonds with hydrogels. Moreover, the scaffold integrates stem cell capturing and homing layers on its bottom and top layers via chemical crosslinking aptamer and loading poly (lactic‐co‐glycolic acid) (PLGA) nanospheres encapsulated with stromal cell‐derived factor‐1α (SDF‐1α), respectively. This design enables the specific capture of bone marrow mesenchymal stem cells (BMSCs) in vivo through aptamer interaction, followed by their mobilization to home in on the hyaline cartilage layer via the chemotaxis of SDF‐1α concentration gradient. Within the scaffold's microenvironment, these BMSCs undergo differentiation into distinct cells for each layer, effectively contributing to the repair of OC defects in rabbits. [ABSTRACT FROM AUTHOR]