Chondrocytes cultured in an adhesive macroporous scaffold subjected to stirred flow bioreactor behave like in static culture

The aim of this study was to evaluate whether mechanical stimulation helps to modulate the redifferentiation of human chondrocytes on adhesive 3D substrates. In a previous work, it was shown that chondrocytes seeded in a non-adherent porous scaffold cluster inside the pores when cultured in a bioreactor and produced extracellular matrix with the components of hyaline cartilage suggesting cellular redifferentiation. The current study followed the same culture protocol for up to 4 weeks using two substrates with good adhesion properties: polycaprolactone (PCL) scaffolds uncoated, and coated with fibrin. The cellular response was characterized by studying the cell-material interaction at short times (6, 24 and 72 h), followed by the use of a biological stirrer to evaluate its effect on the chondrogenesis for 7, 14 and 28 days. The study showed strong cell-substrate interaction in both coated and uncoated scaffolds. In short times, cells adhere to the pore walls, form focal adhesions, develop actin fibers and acquire spread morphology showing the characteristics of a monolayer culture. The use of a bioreactor system was useful for reducing cellular proliferation for up to 14 days but no signs of redifferentiation were found for long culture times.