OBJECTIVETo compare the tissue engineered cartilage constructed with chondrocytes derived from auricular and articular cartilage.

METHODSChondrocytes were isolated from porcine auricular and articular cartilage, and BMSCs were obtained from bone marrow aspirate and cultured. Each kind of chondrocytes were resuspended alone or mixed with BMSCs at a ratio of 1:1, and seeded onto PGA/PLA scaffolds to construct tissue engineered cartilage (n = 4). The constructs were cultured for 8 weeks in vitro and then subcutaneously implanted into nude mice for 6 weeks. The differences between chondrocytes monoculture from articular and auricular cartilage or between each of them co-cultured with BMSCs were evaluated by gross view, measurement of thickness and wet weight, histological examinations including H&E, Safranin O, type II collagen, and Ponceau's & Victoria blue staining, and gene expression analysis of cartilage related genes.

RESULTSNo obvious differences were found histologically among the complexes constructed in vitro 8 weeks except for few elastic fibers secreted in the auricular chondrocytes + BMSCs co-culture group. Neo-cartilage is thicker in the groups of articular chondrocytes (38. 1% than the group of auricular chondrocytes, P < 0.05) and articular chondrocytes + BMSCs co-culture (19.3% than the group of auricular chondrocytes + BMSCs, P < 0.05). However, after 6 weeks in vivo the elastic fibers were found positive in the complexes constructed by auricular chondrocytes, and its staining was even stronger and more homogenous in the group of auricular chondrocytes + BMSCs co-culture. The tissues generated by articular chondrocytes alone and co-cultured with BMSCs both formed the characteristic features of three-layer structure of hyaline cartilage and ossified in vivo with significant up-regulation of COL10A1 and MMP-13. To summarize, auricular chondrocytes formed the elastic cartilage while articular chondrocytes formed the hyaline cartilage during the development of tissue engineered cartilage either by monoculture or the co-culture with BMSCs.

CONCLUSIONSThe chondrogenic response of chondrocytes from different cartilage origins demonstrates that an initial chondrocyte and cartilage type recapitulates the same in later tissue-engineered development.