Abstract: The precise regulation of stem cell fate remains a central challenge in stem cell-based cartilage tissue engineering for post-injury joint regeneration. While stem cell transplantation is considered a promising clinical intervention for early-stage cartilage defects, its therapeutic potential is limited by suboptimal engraftment efficiency, low cell survival rates, and inconsistent differentiation outcomes. DNA nanomaterials, known for their molecular programmability and high biocompatibility, hold promise to improve the outcomes of stem cell-based cartilage repair strategies. However, three-dimensional (2D) DNA biomaterials suffer from limited structural stability and rapid enzymatic degradation, while 3D DNA nanomaterials are complex to fabricate. Herein, we developed a hybrid DNA supramolecular hydrogel that combines the design flexibility of 2D architectures with the mechanical robustness of 3D frameworks. Through molecular dynamics simulation and rolling circle amplification techniques, we synthesized multilayer DNA hydrogels with stable hierarchical organization. The introduction of aptamer structures into the DNA hydrogel network enhanced its affinity for cartilage and mesenchymal stem cells (MSCs). The 3D hydrogel network demonstrated favorable rheological properties, rapid self-healing capacity, and excellent cytocompatibility in vitro. Functional assessments revealed the hydrogel's capacity to mitigate shear-induced cell damage and enhance MSC retention at defect sites. Furthermore, 3D culture experiments demonstrated that the DNA supramolecular hydrogel created an conducive environment for MSCs, effectively supporting their differentiation into cartilage tissue. In vivo evaluation using a rat osteochondral defect model confirmed the efficacy of aptamer-functionalized DNA hydrogels, which showed significant improvements in cartilage regeneration and functional recovery compared to scaffold-free MSC transplantation approaches. This work established a proof-of-concept for engineered DNA-based hydrogels that synergistically improved the protection, spatial retention, and chondrogenic differentiation of delivered MSCs for cartilage repair.
Funding Source: This work was supported by the National Key R&D Program of China (to QYG, 2019 YFA 0110600) and the CNRM (to RST and ZAL), under the Health@InnoHK program launched by the ITC, Hong Kong SAR Government.
