Recent advances in 3D bioprinting for cartilage tissue engineering: Biomimetic strategies, cellular regulation, and future perspectives
Articular cartilage has limited intrinsic repair capacity, and current clinical approaches often fail to restore durable hyaline cartilage. Three-dimensional bioprinting offers spatial control over cells, biomaterials, and bioactive cues, creating opportunities to fabricate patient-specific constructs that recapitulate cartilage architecture and function. However, functional cartilage regeneration cannot be achieved by optimizing printing technology, bioink composition, cell source, or scaffold design in isolation. This review critically examines recent advances in 3D bioprinting for cartilage tissue engineering through an integrated, design-oriented framework. Bioprinting modalities are compared according to their underlying physical mechanisms and their trade-offs in resolution, throughput, bioink compatibility, and cellular stress. Natural, synthetic, and composite bioinks are discussed with emphasis on how rheological behavior, crosslinking, and reinforcement jointly regulate printability, cell-instructive capacity, degradation, and mechanical durability. The roles of chondrocytes, mesenchymal stromal cells, and pluripotent stem cell-derived chondrogenic cells are evaluated in relation to phenotype stability, scalability, safety, and clinical application. At the construct level, pore architecture, mechanical and compositional gradients, fiber alignment, and spatiotemporally controlled factor delivery are considered as interacting regulators of mass transport, matrix organization, regional function, and host integration. A central conclusion is that successful cartilage bioprinting requires balanced optimization of competing objectives, including bioactivity versus printability, printing fidelity versus cytocompatibility, and porosity versus mechanical integrity. Future translation will require standardized, cartilage-specific evaluation of long-term matrix quality, mechanical function, safety, reproducibility, and repair efficacy in clinically relevant models.
