Anti-inflammatory coatings may reduce complications after implant surgery
HALLE (SAALE), Germany: The use of medical implants can be hampered by chronic inflammatory reactions, which may result in failure of the device. Now, researchers at Martin Luther University Halle-Wittenberg (MLU) have developed a new method of applying anti-inflammatory substances to implants in order to inhibit undesirable inflammatory reactions in the body.
It is not uncommon for complications to arise after implantation. The immune system identifies the implant as a foreign body and attempts to remove it. “This is actually a completely natural and useful reaction by the immune system,” said Prof. Thomas Groth, a biophysicist at MLU, in a press release. If this reaction does not subside on its own after a few weeks, it can lead to chronic inflammation and more serious complications. “The immune system attracts various cells that try to isolate or remove the foreign entity. These include macrophages, a type of phagocyte, and other types of white blood cells and connective tissue cells,” explained Groth. Drugs that suppress the immune response in a systemic manner are often used to treat chronic inflammation, but may have undesired side effects.
The research team was seeking a simple way to modify the immune system’s response to an implant in advance. “This is kind of tricky, because we obviously do not want to completely turn off the immune system as its processes are vital for healing wounds and killing pathogens. So, in fact we only wanted to modulate it,” said Groth. Thus, the researchers developed a new coating for implants that contains two substances that are already known to have an anti-inflammatory effect: heparin and hyaluronic acid.
The scientists treated a surface with the two substances by applying a layer that was only a few nanometres thick. “The layer is so thin that it does not affect how the implant functions. However, it must contain enough active substance to control the reaction of the immune system until the inflammatory reaction has subsided,” explained Groth. In cell experiments, the researchers observed how the two substances were absorbed by the macrophages, thereby reducing inflammation in the cell cultures. The untreated cells showed clear signs of a pronounced inflammatory reaction. This is because the active substances inside the macrophages interfere with a specific signalling pathway that is crucial for the immune response and cell death. “Both heparin and hyaluronic acid prevent the release of certain pro-inflammatory messenger substances. Heparin is even more effective because it can be absorbed by macrophage cells,” commented Groth.
The study, titled “Studies on the mechanisms of anti-inflammatory activity of heparin- and hyaluronan-containing multilayer coatings—targeting NF-κB signalling pathway”, was published on 25 May 2020 in the International Journal of Molecular Sciences.