Cartilage engineering using cell-derived extracellular matrix scaffold in vitro

A cell-derived extracellular matrix (ECM) scaffold was constructed using cultured porcine chondrocytes via a freeze-drying method, and its ability to promote cartilage formation was evaluated in vitro. Scanning electron microscope (SEM) revealed that the scaffold had highly uniform porous microstructure. Then, rabbit chondrocytes were seeded dynamically on ECM scaffold and cultured for 2 days, 1, 2, and 4 weeks in vitro for analysis. Polyglycolic acid (PGA) scaffold was used as a control. On gross observation of neocartilage tissue, a silvery white cartilage-like tissue was observed after 1 week of culture in ECM scaffold, while similar morphology was seen only after 4 weeks in PGA scaffold. The volume of neocartilage-like tissue was significantly increased in both ECM and PGA groups. The compressive strength was gradually increased with time in ECM group, while gradually decreased in PGA group. DNA, glycosaminoglycan (GAG) and collagen contents also increased gradually with time in both groups, but showed more significant increase in ECM group. Histological staining for GAG (Safranin O staining) and type II collagen (immunohistochemistry) showed sustained accumulation of ECM molecules with time, which gradually and uniformly filled porous space in ECM scaffold. On the contrary, they accumulated only at the peripheral area of PGA scaffold. These results suggest that a novel cell-derived ECM scaffold can provide a promising environment for generating a high quality cartilage in vitro.