3D-Printed Negative Poisson's Ratio Composite Scaffolds with Antibacterial and Microenvironment Remodeling Capacities for Ameliorating Intervertebral Disc Degeneration.

During the process of intervertebral disc degeneration (IDD), localized inflammatory responses occur, triggering an imbalance in the decomposition and metabolism of nucleus pulposus (NP) cells, which subsequently leads to the functional impairment of the intervertebral disc. Inspired by the negative Poisson's ratio (NPR) effect, a composite ink composed of gelatin methacrylate and polyethylene glycol diacrylate is designed for 3D-printing scaffolds exhibiting NPR properties. Finite element simulation results indicate that the NPR composite scaffold provides uniform stress distribution under NP swelling and can exert a counterforce to inhibit NP protrusion. Additionally, tannic acid is adsorbed on the scaffold's surface, endowing it with antioxidant, anti-inflammatory, and antibacterial properties. In vitro experiments show that the encapsulated anti-inflammatory drug Curcumin and YES-associated protein agonist TT-10 delivered by liposomes within ink can be released continuously in the conditions of high reactive oxygen species and inflammatory cytokine overexpression, providing significant protection to NP cells. In vivo tests demonstrate that the NPR scaffold implanted in situ alleviates the IDD process in a rat model by maintaining disc height. This 3D-printed scaffold system with drug delivery and NPR properties represents an innovative and promising strategy for IDD tissue engineering therapy.