3D Contour Printing of Anatomically Mimetic Cartilage Grafts with Microfiber-Reinforced Double-Network Bioink

Bioprinting is an emerging technology for fabricating cell-laden scaffolds with custom shapes that resemble the complex architecture of human tissues, however, construction of mechanically competent tissue grafts which mimic irregular cartilage defect is still a big challenge. Here, 3D printing of short fiber-reinforced double-network bioink to generate anatomically accurate and mechanical tunable scaffold for cartilage regeneration is reported. Poly(lactic acid) (PLLA) short fibers are first prepared by electrospinning and then fragmented through aminolysis reaction. Composite inks are constructed with an incorporation of fragmented microfibers with varied amounts and lengths into oxidized alginate bioink. The results show that incorporation of PLLA short fibers not only improves the printing fidelity but also facilitates in generating mechanically strong constructs. By incorporating gelatin methacryloyl (GelMA) and optimizing the bioink composition, the fabricated constructs with a compressive stress of ≈150 kPa even after 100 cyclical compression loading (up to 40% of strain) are achieved. In addition, this mechanically reinforced alginate/GelMA double-network bioink displays good biocompatibility and supports bone marrow-derived stromal cell chondrogenesis in vitro. Collectively, these findings demonstrate this approach is capable of printing engineered grafts which resemble the irregular size and mechanical properties of cartilage and thus hold potential for functional tissue regeneration.