New Implant Coatings Make Them More Biocompatible

A new method of applying anti-inflammatory substances can inhibit undesirable inflammatory reactions to implants, claims a new study.

Researchers at the Martin Luther University Halle-Wittenberg (MLU; Halle-Wittenberg; Germany), the University of Niš (Serbia), and other institutions conducted a study to examine the anti-inflammatory properties of surface coatings made of either hyaluronic acid (HA) or heparin (H) in combination with chitosan, prepared as multilayers through a layer-by-layer deposition technique. The properties of the glycosaminoglycan (GAG)-modified surfaces were then characterized in terms of surface topography, thickness, and wettability.

The results showed a higher thickness and hydrophilicity after multilayer formation. The multilayers containing either HA or H dampened the inflammatory response visible by reduced adhesion, formation of multinucleated giant cells and interleukin release, and a significant decrease in macrophages on GAG-based multilayers, with the macrophages able to associate with and take up both HA and H. Overall, the heparin-based multilayers demonstrated the most suppressive effect on macrophage activation after implantation of medical devices. The study was published on May 25, 2020, in the International Journal of Molecular Sciences.

“The immune system attracts various cells that try to isolate or remove the foreign entity; these include macrophages. 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,” said senior author Professor Thomas Groth, PhD, of the MLU Institute of Pharmacy. “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.”

Chitosan is a linear polysaccharide composed of randomly distributed glucoseamine deacetylated unit and acetylated units. It is made by treating shrimp and other crustacean shells with the alkali sodium hydroxide. Chitosan also has a number of commercial uses, such as a seed treatment and biopesticide, helping plants to fight off fungal infections. In winemaking it can be used as a fining agent, and it can also be used in self-healing polyurethane paint coating.

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Martin Luther University Halle-Wittenberg
University of Niš