Comparison of cartilage specific markers in articular and differentiated chondrocytes in pellet system release_o2qixgb2wjgdpn5z52fg4gjx3i

Abstract

Autologous cartilage replacement has the inherent advantage that the transplanted tissue is immunogenically neutral. However, chondrocyte isolation, proliferation, and dedifferentiation limitations resulted in the search for a cell type that would overcome the aforementioned limitations. Here we investigated if adipose-derived stem cells (ADSCs), which are easy to isolate in large quantities, in combination with a three dimensional culture system and growth factor would be a suitable alternative for autologous cartilage replacement. In this study ADSCs and human articular chondrocytes were allowed to differentiate in pellet culture in the presence or absence of transforming growth factor-β3 (TGF-β3) for 14 days and their chondrogenic potential was evaluated. Pellets were microscopically and histologically evaluated for structure and morphology. Matrix production was assayed using immunohistochemistry for collagen types Ι and ΙΙ, and aggrecan. Images were evaluated via custom-made routines programmed in MATLAB. Oval to round cell pellets were formed with an overall homogenous dense central structure that consisted of isogenic groups with walled-off chondrocytes in their lacunae and encircled by basophilic extracellular matrix (ECM). Our results show that in the presence of TGF-β3, collagen type I expression was 2-fold and aggrecan expression was 3-fold higher in differentiated ADSCs compared with articular chondrocytes, whereas collagen type II was reduced by a factor of 1.58. Furthermore, the absence of TGF-β3 nearly completely suppressed collagen type I in both cell types, whereas aggrecan expression remained unaffected in ADSCs and was reduced 1.87-fold in articular chondrocytes. Pellet culture of ADSCs-derived chondrocytes represents a viable alternative for autologous cartilage replacement. The high cell density and more natural three-dimensional environment of pellet culture attenuated dedifferentiation of cells. Although we obtained a mixed chondrogenic phenotype with increased collagen type I expression, the extent of this increase was lower compared to reports in the literature. Furthermore, ADSCs-derived chondrocytes expressed large amounts of aggrecan, which is an essential component of the ECM in articular cartilage. Finally, TGF-β3 might be used to direct chondrogenic differentiation and reduce collagen type I expression by controlling concentration and treatment duration with TGF-β3.
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