Chondrogenic differentiation of human bone marrow mesenchymal stem cells in chitosan based scaffolds using a flow perfusion bioreactor

Native articular cartilage is subjected to synovial fluid flow during normal joint function. Thus,
it is believed that the morphogenesis of articular cartilage may be positively regulated by the
application of similar stimulation in vitro. In the present study, the effect of fluid flow over the
chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBM-MSCs)
was investigated. We intended to find out whether the shear stress caused by perfusion of the
medium through the constructs was capable of augmenting the differentiation process. Human
BMSCs were isolated from bone marrow aspirates and were characterized by flow cytometry.
After expansion, hBM-MSCs were seeded statically onto fibre mesh scaffolds, consisting of a blend
of 50 : 50 chitosan : poly(butylene terephthalate adipate) (CPBTA). Constructs were cultured in a
flow-perfusion bioreactor for 28 days, using complete medium for chondrogenesis supplemented by
TGFβ3. An enhanced ECM deposition and collagen type II production was observed in the bioreactor
samples when compared to the static controls. Moreover, it was observed that hBM-MSCs, in static
cultures, take longer to differentiate. ECM accumulation in these samples is lower than in the
bioreactor sections, and there is a significant difference in the expression of collagen type I. We
found that the flow-induced shear stress has a beneficial effect on the chondrogenic differentiation
of hMSCs.