Study on bioactive PEGDA/ECM hybrid bi-layered hydrogel scaffolds fabricated by electro-writing for cartilage regeneration

Articular cartilage injury is a common disease in orthopedics. Because of the poor repair ability of articular cartilage itself, medical intervention is often required for articular cartilage injury. A promising tool for cartilage injury repair is electro-writing (EW), a 3D printing technology, which can be used to prepare high-precision and high-porosity layered active scaffolds, thereby allowing it to imitate the layered structure of cartilage. In this study, we developed a hybrid ink with good EW printability and formability based on polyethylene glycol diacrylate (PEGDA) and extracellular matrix, in which cells can be mixed for printing. Moreover, growth factors were also integrated into the printed material, such that the upper layer of the scaffold was loaded with transforming growth factor-β1 (TGF-β) + bone morphogenetic protein-7 (BMP-7) and the lower layer was loaded with TGF-β+insulin growth factor-1 (IGF-1). The whole scaffold encompassed layered active ingredients and can functionally repair damaged cartilage after being implanted in the body. In summary, this study explored the printability and formability of EW hydrogel inks, based on which an original hybrid cell hydrogel ink was developed for constructing a bioactive cartilage repair scaffold capable of inducing cell differentiation to promote cartilage repair.