Artificial Periosteum with Oriented Surface Nanotopography and High Tissue Adherent Property.

Massive periosteal defects often significantly impair bone regeneration and repair, which have become a major clinical challenge. Unfortunately, current engineered periosteal materials can hardly currently focus on achieving high tissue adhesion property, being suitable for cell growth, and inducing cell orientation concurrently to meet the properties of nature periosteum. Additionally, the preparation of oriented surface nanotopography often relies on professional equipment. In this study, inspired by the oriented collagen structure of nature periosteum, we present a composite artificial periosteum with a layer of oriented nanotopography surface containing carbon nanotubes (CNTs), cross-linked with adhesive polydopamine (PDA) hydrogel on both terminals. An oriented surface structure that can simulate the oriented alignment of periosteal collagen fibers can be quickly and conveniently obtained via a simple stretching of the membrane in a water bath. With the help of CNTs, our artificial periosteum exhibits sufficient mechanical strength and desired oriented nanotopological structure surface, which further induces the directional arrangement of human bone marrow mesenchymal stem cells (hBMSCs) on the membrane. These oriented hBMSCs express significantly higher levels of osteogenic genes and proteins, while the resultant composite periosteum can be stably immobilized in vivo in the rat model of massive calvarial defect through the PDA hydrogel, which finally shows promising bone regeneration ability. We anticipate that the developed functional artificial periosteum has great potential in biomedical applications for the treatment of composite defects of the bone and periosteum.

3D-printed fish gelatin scaffolds for cartilage tissue engineering.

Knee osteoarthritis is a chronic disease caused by the deterioration of the knee joint due to various factors such as aging, trauma, and obesity, and the nonrenewable nature of the injured cartilage makes the treatment of osteoarthritis challenging. Here, we present a three-dimensional (3D) printed porous multilayer scaffold based on cold-water fish skin gelatin for osteoarticular cartilage regeneration. To make the scaffold, cold-water fish skin gelatin was combined with sodium alginate to increase viscosity, printability, and mechanical strength, and the hybrid hydrogel was printed according to a pre-designed specific structure using 3D printing technology. Then, the printed scaffolds underwent a double-crosslinking process to enhance their mechanical strength even further. These scaffolds mimic the structure of the original cartilage network in a way that allows chondrocytes to adhere, proliferate, and communicate with each other, transport nutrients, and prevent further damage to the joint. More importantly, we found that cold-water fish gelatin scaffolds were nonimmunogenic, nontoxic, and biodegradable. We also implanted the scaffold into defective rat cartilage for 12 weeks and achieved satisfactory repair results in this animal model. Thus, cold-water fish skin gelatin scaffolds may have broad application potential in regenerative medicine.