Black bioceramic scaffolds with micro/nano surface structure inducing mild hyperthermal environment for regenerating osteochondral defects

The treatment of osteochondral defects remains a huge challenge in clinic. The thermotherapy in traditional Chinese medicine is widely used in treating joint disease because the mild heat stimulation can promote the nutrient circulation. Inspired by the function of thermotherapy, we design a new thermotherapy strategy by using black bioceramic scaffolds to build local mild hyperthermal environment for treating osteochondral defects. Herein, black akermanite (B-AKT) bioceramic scaffolds with micro/nano surface structure and excellent photothermal conversion property are successfully fabricated. The temperature of scaffolds can be precisely controlled by near infrared (NIR) irradiation to construct a mild hyperthermal environment (~41°C). The micro/nanostructure on the scaffolds surface well promoted the cell adhesion and nutrition absorption by activating integrins and focal adhesion kinase (FAK). Meanwhile, the mild hyperthermal environment constructed by B-AKT scaffolds can simultaneously induce the chondrogenesis and osteogenesis both in vitro and in vivo by activating the expression of cellular heat shock proteins (HSPs) and corresponding signaling pathways. Furthermore, in rabbit osteochondral defects, mild hyperthermal environment induced by B-AKT scaffolds exhibits stimulatory effects on the integrated regeneration of cartilage and bone. This study proposes a novel therapy strategy of constructing local mild hyperthermal environment by black bioceramic scaffolds to treat osteochondral defects and other joint diseases.