Effects of spreading areas and aspect ratios of single cells on dedifferentiation of chondrocytes

Dedifferentiation of chondrocytes is common in culturing, and seriously affects the restorative efficacy of cartilage repair. The present study examines the effect of initial cell shapes on dedifferentiation of chondrocytes in vitro. The cell shape was controlled with a unique material micropatterning technique. With this technique, a series of microarrays of cell-adhesive peptide arginine-glycine-aspartate (RGD) were generated on a persistent non-fouling poly(ethylene glycol) (PEG) hydrogel. After culturing chondrocytes derived from rats on the micropatterned surfaces, the cell shapes were adapted by the geometries of adhesive microislands with pre-defined diameters (10, 15, 20 and 30 μm) for round ones and aspect ratios (1, 1.2, 1.5, 2, 4 and 6) for elliptical ones. After 10 days, collagen II staining was demonstrated to identify normal chondrocytes and dedifferentiated cells for those single cells on microislands. Furthermore, the gene expression of collagen II, collagen I, aggrecan and SOX9 were detected by qRT-PCR. The statistical results illustrated that dedifferentiation of chondrocytes happened more probably in the cases of larger sizes and higher aspect ratios. The conclusions stand under circumstances of both normoxia (21% O2) and hypoxia (5% O2) atmospheres.