Collagen-modified porous bacterial cellulose tri-layer scaffolds for osteochondral defect repair

Construction of integrated porous tri-layer osteochondral scaffolds that can both mimic the complex structure of the osteochondral region and be endowed with bioactivity is highly desirable for osteochondral defect repair. Herein, we fabricated an integrated porous bacterial cellulose (IPBC) scaffold via laser etching, then modified it with type I collagen to obtain collagen-functionalized IPBC (CIPBC-1-3) scaffolds. Compared with IPBC, collagen modification significantly increased fiber diameter of the scaffolds and decreased their porosity. In this context, the porosity of IPBC and CIPBC-1-3 was 88.6 ± 3.0%, 85.6 ± 3.4%, 80.9 ± 1.2%, and 77.5 ± 2.2%, respectively. Furthermore, the collagen modification also enhanced mechanical strength of IPBC. In vitro experiments demonstrated that, compared with IPBC, CIPBC-1-3 scaffolds promoted chondrocyte and MC3T3-E1 cell adhesion, spreading, and proliferation, with CIPBC-2 showing optimal biocompatibility. In vivo rabbit osteochondral defect models confirmed that, when compared with IPBC, CIPBC-2 (selected as the model) accelerated bone-cartilage regeneration at 6 and 12 weeks post-implantation, as evidenced by micro-CT and histological analyses. This study provides a biomimetic collagenized integrated porous tri-layer scaffold with great potential for osteochondral tissue engineering.