Acellular cartilage matrix scaffolds for cartilage regeneration: current progress and future directions

When blood vessels no longer reach the joint surface, cartilage lesions lose almost all ability to repair themselves, and the defect often progresses to osteoarthritis, with daily comfort declining steadily. Today's treatments usually induce the formation of fibrocartilage, whose mechanical properties remain inferior to those of the original tissue, so full restoration is still out of reach. Acellular cartilage matrix, prepared by removing cellular components through thorough washing until only the extracellular framework remains, retains the native biochemical composition while reducing the immune-reactive signals. This provides surgeons with a scaffold well-matched to host cells. This review outlines the diverse fabrication protocols for ACM, the characterization assays for its evaluation, the joints it can be harvested from, the animal models that mimic human cartilage defects, and the chemical modifications designed to enhance its performance. Future ACM will probably be tailored to each patient, laced with bioactive cues that drive the tissue to rebuild itself. This will be achieved while maintaining low immune rejection, brisk tissue repair, and wide biocompatibility, although scientists still have to establish standardized protocols and monitor the material's long-term performance years after implantation.