Bilayered HA/CS/PEGDA hydrogel with good biocompatibility and self-healing property for potential application in osteochondral defect repair

The fabrication of osteochondral tissue engineering scaffolds comprised of different layers is a big challenge. Herein, bilayers comprised of double network hydrogels with or without nano hydroxyapatite (HAp) were developed by exploiting the radical reaction of poly(ethylene glycol) diacrylate (PEGDA) and the Schiff-base reaction of N-carboxyethyl chitosan (CEC) and oxidized hyaluronic acid sodium (OHA) for osteochondral tissue engineering. The bilayered osteochondral scaffold was successfully fabricated based on the superior self-healing property of both hydrogels and evaluated by scanning electron microscopy, macroscopic observation and mechanical measurements. In addition, the hydrogels exhibited good biocompatibility as demonstrated by the in vitro cytotoxicity and in vivo implantation tests. The results indicated that the bilayered hydrogel had great potential for application in osteochondral tissue engineering.