Organic films with amino groups on nanofibrous structure control innate immune response

Synthetic polymer nanofibers, such as polycaprolactone (PCL), are widely used as scaffolds in tissue engineering due to their ease of fabrication. However, their surface properties often fail to meet the specific requirements of cell culture. Coating the scaffolds with organic thin films containing amino groups using a plasma-based dry method provides a simple, single-step, and tunable approach to enhance their hydrophilicity. Motivated by the potential application of these films in bioengineering, this study investigates key characteristics influencing the immune response, capturing both the early and late stages of immune activation represented here by neutrophil-like and macrophage-like cell models, respectively. In neutrophils, the strongest undesirable pro-inflammatory activation was triggered by films with high nitrogen content, positive surface charge, and low water stability, as evidenced by elevated expression of pro-inflammatory cytokines. Macrophage-like cells exhibited a similar trend, albeit with a shifted activation threshold: amine films characterized by lower nitrogen content more effectively reduced pro-inflammatory activation. Morphological changes in macrophage-like cells further supported the role of surface chemistry in modulating their behavior. In addition to surface chemistry, substrate morphology played a role in immune modulation. The porous structure of PCL nanofibers enhanced the immune profile of macrophage-like cells by increasing pro-regenerative M2 cytokine expression and reducing pro-inflammatory M1 markers. In contrast, neutrophil-like cells were largely unaffected by substrate morphology and responded primarily to surface chemistry. This study underscores the importance of immune response investigation in biomaterial design. • Response of neutrophil- and macrophage-like cells to organic films with amino groups. • The gene expression profiles, cytokine production and cell morphology were correlated. • Optimized nitrogen and amino group content is a key to reduced inflammation. • Nanofibrous structure promotes pro-regenerative response in macrophage-like cells.