A biomimetic bi-layered tissue engineering scaffolds for osteochondral defects repair

Osteochondral defects are most commonly characterized by damages to both cartilage and underlying subchondral bone tissues,thus developing bi-layered scaffold that can concurrently regenerate these two specific lineages becomes challenge. In this study,the highly biomimetic bi-layered scaffolds were successfully prepared using human-like-collagen(HLC), hyaluronan(HA) and nano hydroxyapatite(HAP) particles, combined with "liquid phase synthesis" technology, freeze-drying and chemical crosslinking techniques, which was simulated the composition of natural extracellular matrix to repair osteochondral defects. This novel bilayer osteochondral graft had a seamlessly integrated layer structure, suitable pore size, high levels of porosity, and excellent mechanical properties. In vitro cell experiments of the bilayer scaffold indicated that the scaffold could promote the proliferation and adhesion of human bone marrow mesenchymal stem cells. In vivo osteochondral defects and micro-CT experiment revealed that bilayer scaffolds showed complete closure of the defect. Histology confirmed collagen and glycosaminoglycans were deposited in the new matrix of hyaline cartilage and bone in the bilayer scaffold group. Therefore, the developed bionic bilayer scaffold enhanced the regeneration of hyaline cartilage through subchondral bone formation and lateral host-tissue integration. In conclusion, this bilayer scaffold based on HLC could be used as the desired strategy for osteochondral defects regeneration.