Transplantation of allogenic chondrocytes with chitosan hydrogel-demineralized bone matrix hybrid scaffold to repair rabbit cartilage injury

Cartilage tissue engineering is the hotspot of cartilage repair. The allogenic chondrocytes appear to be a promising source of seed cells in cartilage tissue engineering. In this study, we aimed to transplant allogenic chondrocytes with chitosan hydrogel (CS)-demineralized bone matrix (DBM) hybrid scaffold (CS/DBM) to repair rabbit cartilage injury with one-step operation. After the CS/DBM scaffold was successfully fabricated, it showed that the porous CS filled the large pores of DBM, which improved the distribution of seed cells in the CS/DBM scaffold. The allogenic chondrocytes at second passage were transplanted with different scaffolds to repair rabbit cartilage injury. Twenty-four weeks after surgery, the cartilage defect in the CS/DBM group was successfully filled as shown by MRI. Moreover, the histological score of CS/DBM group was significantly higher than that of the other groups. On the aspect of biomechanical property, the regenerated cartilage in the CS/DBM group were superior to those in the other groups as determined by nanoindentation. Meanwhile, no obvious inflammatory response was observed after the transplantation of allogenic chondrocytes at 24 weeks post-surgery. Furtherly, gene expression profile for cells within the repair tissue was compared with the allogenic chondrocytes before transplantation using Agilent microarray and RT-qPCR. The results showed that some genes beneficial to cartilage regeneration, such as BMP-7, HGF, and IGF-1, were upregulated one month after transplantation. Consequently, our study demonstrated that the transplantation of allogenic chondrocytes with CS/DBM scaffold successfully repaired rabbit cartilage injury with only one-step operation, thereby providing new insights into cartilage tissue engineering.