Abstract
The implantation of biomedical devices, including collagen-based implants, evokes an inflammatory response. Despite inflammation playing an important role in the early stages of wound healing, excessive and non-resolving inflammation may lead to the poor performance of biomaterial implants in some patients. Therefore, steps should be taken to control the level and duration of an inflammatory response. In this study, oxygen and nitrogen gas plasmas were employed to modify the surface of collagen film, with a view to modifying the surface properties of a substrate in order to induce changes to the inflammatory response, whilst maintaining the mechanical integrity of the underlying collagen film. The effects of cold plasma treatment and resultant changes to surface properties on the non-specific inflammatory response of the immune system was investigated in vitro in direct contact cell culture by the measurement of protein expression and cytokine production after one and four days of human peripheral blood mononuclear cell (PBMC) culture. The results indicated that compared to oxygen plasma, nitrogen plasma treatment produced an anti-inflammatory effect on the collagen film by reducing the initial activation of monocytes and macrophages, which led to a lower production of pro-inflammatory cytokines IL-1β and TNFα, and higher production of anti-inflammatory cytokine IL-10. This was attributed to the combination of the amino chemical group and the significant reduction in roughness associated with the introduction of the nitrogen plasma treatment, which had an effect on the levels of activation of the adherent cell population.