Comparison of human articular chondrocyte and chondroprogenitor cocultures and monocultures: To assess chondrogenic potential and markers of hypertrophy

Abstract

Background and ObjectiveIn the field of cartilage repair, use of two or more cell populations such as mesenchymal stem cells with chondrocytes in an in-vitro co-culture synergistic environment has been attempted to evade limitations of monoculture systems and promote/induce chondrogenesis. Articular cartilage-derived chondroprogenitors (CPs), considered to have stem-cell like characteristics have been proposed as a potential contender for neocartilage development. Our objective was to assess whether co-cultures using different ratios of chondrocytes(C) and CPs would demonstrate better results in terms of growth kinetics, surface marker expression, chondrogenic potential, tendency for hypertrophy and glycosaminoglycan deposition than monocultures. Study designHuman chondrocytes and CPs (fibronectin adhesion assay) from the same cartilage source were isolated. Passage 2 cells were subjected to monolayer/pellet cultures and were grown as monocultures and cocultures at the following percentage ratios(C:CP) 80:20, 65:35, 50:50, 35:65 and 20:80. ResultsAnalysis of data acquired from population doubling, flow cytometry, RT-PCR and Safranin O uptake demonstrated similar results in all monoculture and co-culture groups with no significant inter-group variation, even when reported specific markers of identification (CD54 and CD44:chondrocyte markers) and isolation (CD29 and CD49e: forming heterodimeric fibronectin receptor for CP sorting) were examined. ConclusionIn conclusion, this study suggests the need for improved sorting techniques based on a characteristic differentiating biomarker for selection of cells which are true representatives of CPs possessing properties of enhanced chondrogenesis and reduced hypertrophy.