Three-dimensional kagome structures in a PCL/HA-based hydrogel scaffold to lead slow BMP-2 release for effective bone regeneration

Osteoconductive function is remarkably low in bone disease in the absence of bone tissue surrounding the grafting site, or if the bone tissue is in poor condition. Thus, an effective bone graft in terms of both osteoconductivity and osteoinductivity is required for clinical therapy. Recently, the three-dimensional (3D) kagome structure has been shown to be advantageous for bone tissue regeneration due to its mechanical properties. In this study, a polycaprolactone (PCL) kagome-structure scaffold containing a hyaluronic acid (HA)-based hydrogel was fabricated using a 3D printing technique. The retention capacity of the hydrogel in the scaffold was assessed in vivo with a rat calvaria subcutaneous model for 3 weeks, and the results were compared with those obtained with conventional 3D-printed PCL grid-structure scaffolds containing HA-based hydrogel and bulk-type HA-based hydrogel. The retained hydrogel in the kagome-structure scaffold was further evaluated by in vivo imaging system analysis. To further reinforce the osteoinductivity of the kagome-structure scaffold, a PCL kagome-structure scaffold with bone morphogenetic protein-2 (BMP-2) containing HA hydrogel was fabricated and implanted in a calvarial defect model of rabbits for 16 weeks. The bone regeneration characteristics were evaluated with hematoxylin and eosin (H&E), Masson’s trichrome staining, and micro-CT image analysis. Graphic abstract