Cartilage defects are most commonly seen in the knee joint, however, due to the limited self-recovery ability of cartilage, the repair of articular cartilage defects is still a great challenge despite that various approaches were proposed. We designed a strategy to the induction of cartilage repair using ABM (acellular bone matrix) create an appreciate microenvironment for the in-situ cells with easy surgical application.
An in vitro system including Scanning electron microscopy (SEM), nanoindentation were used to assess the biomechanical property of the scaffold, while confocal microscopy, and 1,9-dimethylmethylene blue assay were used to assess the adherence, proliferation, and cartilage matrix production of the cells seeded on the scaffold.
Preclinical experiment was carried on a mini-pig cartilage repair model, in which full-thickness defects were produced in the articular cartilage of the trochlear groove of the mini-pig. A total of 36 knee joints of 18 pigs were included and equally divided into 3 groups, undergoing ABM combined with Microfracture (ABM+M group), ABM alone (ABM group), and Microfracture alone (M group). Two pigs (4 knees) in each group were sacrificed at 6, 12, or 24 weeks after the operation, and the repaired tissues were analyzed by histological examination, assessment of matrix staining, SEM, and nanoindentation of biomechanical properties.
The in vitro assessments demonstrated the ABM scaffold could promote cell adhesion, growth and proliferation as well as the chondrogenisis of mesenchymal stem cells. Preclinical experiment in the mini-pig cartilage repair model showed regeneration of hyaline cartilage repair. The biomechanical property of the repaired tissue was similar to that of normal cartilage. The integration of repaired tissue and normal tissue in the ABM+M group were better than other two groups.
This ABM-based, one-stage, minimally-invasive, in situ procedure for cartilage regeneration has the potential to improve the treatment of articular cartilage defects.