Physicochemical properties and biocompatibility of the bi-layer polyvinyl alcohol-based hydrogel for osteochondral tissue engineering

Osteochondral defect regeneration was a great challenge because of limited self-repaired ability for its sophisti-cated hierarchical inner structure. Hereon, the bi-layer hydrogel with robust osteochondral interfacial bonding was formulated under fully physical crosslinking, which was consisted of polyvinyl alcohol/collagen II for carti-lage layer and polyvinyl alcohol/biphasic calcium phosphate/carbon nanotubes for bone layer. The bi-layer hy -drogel with irregular pore distribution showed decreased pore size from top to bottom. The tensile modulus of bi-layer hydrogel reached to 7.14 +/- 3 MPa and the stretched fracture surfaces were always appeared in the upper hydrogels, proving bi-layer hydrogels' well interfacial bonding strength. Furthermore, hydrogels' biocom-patibility was evaluated using two kinds of cells in vitro, and the repair performance was also assessed in vivo test. The results demonstrated the bi-layer hydrogel owned favorable cytocompatibility and could induce the for-mation of osteochondral regeneration. Additionally, the max load at defect section reached to 67.24 +/- 36.06 N after 12 weeks regeneration, verifying well bonding strength between the neotissue and native adjacent tissues. This work revealed the favorable bi-layer hydrogel owed great potential in repairing osteochondral defects. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The study developed a bilayer hydrogel with robust interfacial bonding for osteochondral defect regeneration, demonstrating favorable cytocompatibility and the ability to induce osteochondral regeneration. The results also showed well bonding strength between the neo-tissue and native adjacent tissues, suggesting great potential for repairing osteochondral defects.