Characterization of human articular chondrocytes and chondroprogenitors derived from non-diseased and osteoarthritic knee joints to assess superiority for cell-based therapy.

PURPOSE: Cell based therapy is constantly underway since regeneration of genuine hyaline cartilage is under par. Much attention has been afforded to chondroprogenitors recently, as an alternative cell substitute for cartilage repair. Although single source derivation of chondrocytes and chondroprogenitors is advantageous, lack of a characteristic differentiating marker obscures clear identification, which is essential to create a biological profile and is also required to assess cell type superiority for cartilage repair.
METHODS: Cells obtained from three non-diseased/osteoarthritic human knee joints each, were expanded in culture up to passage 10. Characterization studies were performed using flow cytometry; gene expression was studied using RT-PCR; growth kinetics and tri-lineage differentiation was also studied to construct a better profile of chondroprogenitors as well as chondrocytes. RESULTS AND
CONCLUSION: Our results showed that both cell populations exhibited similar cell surface characteristics except for non-diseased chondroprogenitors, which showed markedly low expression of CD34 and high expression of CD166. Trilineage data was suggestive of multilineage potential for both cell types with chondroprogenitors showing notably higher glycosaminoglycan and lower calcified matrix deposition. Data acquired from this study aided in describing cellular behavior of human articular cartilage derived chondroprogenitors in conditions not reported earlier. Our comparative analysis suggests that sorting based on a combination of markers (CD34- and CD166+) would yield a population of cells with minimal contamination by chondrocytes, which may provide translatable results in terms of enhanced chondrogenesis and reduced hypertrophy; both indispensable for the field of cartilage regeneration.