Gold Nanorods Combined with an Near Infrared Laser for the Establishment of a Precise Posttraumatic Osteoarthritis Model

Objective: To investigate the innovative application of gold nanorods combined with a laser in posttraumatic osteoarthritis (PTOA) modeling and to discuss the possible mechanisms. Methods: Electron microscopy was used to characterize the gold nanorods. Cell counting kit-8 assay and enzyme-linked immunosorbent assay were used to evaluate cell proliferation and cytotoxicity. An infrared spectroscopy (IR) thermal camera was used to monitor the temperature changes of gold nanorods with or without the laser treatment. Furthermore, western blotting was used to evaluate the expression of related proteins in response to the indicated treatments. Finally, microcomputed tomography (micro-CT) was used to determine the structural changes in knee joints. Changes in the cartilage and various other tissues were assessed by histological examination. Results: The characteristics and biosafety of the gold nanorods were confirmed. Our study showed that gold nanorods combined with the laser inhibited cell viability, but the gold nanorods or laser alone did not affect cell viability. Moreover, the effect on cell viability was time dependent. Similarly, only gold nanorods with the laser caused the apoptosis of cartilage cells and the upregulation of IL-1β, MMP-13 and Comp. We injected gold nanorods and used laser irradiation to develop an osteoarthritis (OA) model. The temperature of the knees in the OA model increased to 60 °C and then remained at approximately 60 °C. As the time increased, gold nanorods combined with the laser caused more injuries and degeneration in the knee joints. Conclusion: OA models that were established using gold nanorods and a laser were precise, controllable, observable and stable and could be an excellent premise for investigating the exact mechanisms underlying OA and exploring new treatment strategies.