Inflammation and subsequent fibrotic encapsulation that occur after implantation of biomaterials are issues that fostered efforts in designing novel biocompatible materials to modulate the immune response. In this study, glycosaminoglycans (GAG) like hyaluronic acid (HA) and heparin (Hep) that possess anti‐inflammatory activity were covalently bound to NH2‐modified surfaces using EDC/NHS cross‐linking chemistry. Immobilization and physical surface properties were characterized by atomic forces microscopy, water contact angle studies and streaming potential measurements demonstrating the presence of GAG on the surfaces that became more hydrophilic and negatively charged compared to NH2‐modified. THP‐1 derived macrophages were used here to study the mechanism of action of GAG to affect the inflammatory responses illuminated by studying macrophage adhesion, the formation of multinucleated giant cells (MNGCs) and IL‐1β release that were reduced on GAG‐modified surfaces. Detailed investigation of the signal transduction processes related to macrophage activation was performed by immunofluorescence staining of NF‐κB (p65 subunit) together with immunoblotting. We studied also association and translocation of FITC‐labeled GAG. The results show a significant decrease in NF‐κB level as well as the ability of macrophages to associate with and take up HA and Hep. These results illustrate that the anti‐inflammatory activity of GAG is not only related to making surfaces more hydrophilic, but also their active involvement in signal transduction processes related to inflammatory reactions, which may pave the way to design new anti‐inflammatory surface coatings for implantable biomedical devices.

The use of implants can be hampered by chronic inflammatory reactions, which may result in failure of the implanted device. To prevent such an outcome, the present study examines the anti-inflammatory properties of surface coatings made of either hyaluronic acid (HA) or heparin (Hep) in combination with chitosan (Chi) prepared as multilayers through the layer-by-layer (LbL) technique. The properties of glycosaminoglycan (GAG)-modified surfaces were characterized in terms of surface topography, thickness and wettability. Results showed a higher thickness and hydrophilicity after multilayer formation compared to poly (ethylene imine) control samples. Moreover, multilayers containing either HA or Hep dampened the inflammatory response visible by reduced adhesion, formation of multinucleated giant cells (MNGCs) and IL-1β release, which was studied using THP-1 derived macrophages. Furthermore, investigations regarding the mechanism of anti-inflammatory activity of GAG were focused on nuclear transcription factor-кB (NF-κB)-related signal transduction. Immunofluorescence staining of the p65 subunit of NF-κB and immunoblotting were performed that showed a significant decrease in NF-κB level in macrophages on GAG-based multilayers. Additionally, the association of FITC-labelled GAG was evaluated by confocal laser scanning microscopy and flow cytometry showing that macrophages were able to associate with and take up HA and Hep. Overall, the Hep-based multilayers demonstrated the most suppressive effect making this system most promising to control macrophage activation after implantation of medical devices. The results provide an insight on the anti-inflammatory effects of GAG not only based on their physicochemical properties, but also related to their mechanism of action toward NF-κB signal transduction.

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Surface coatings prepared by layer‐by‐layer technique permit loading of growth factors (GFs) and their spatially controlled release. Here, native chondroitin sulfate (nCS), oxidized CS (oCS100), or mixture of both (oCS50) are combined with collagen I (Col I) to fabricate polyelectrolyte multilayers (PEMs) that exhibit structural, mechanical, and biochemical cues like the natural extracellular‐matrix. The use of oCS enables intrinsic cross‐linking of PEM that offers higher stability, stiffness, and better control of bone morphogenetic protein‐2 (BMP‐2) release compared to nCS. oCS100 PEMs have enhanced stiffness, promote Col I fibrillization, and present BMP‐2 in a matrix‐bound manner. oCS50 PEMs show intermediate effects on osteogenesis, soft surface, high water content but also moderately slow BMP‐2 release profile. C2C12 myoblasts used for osteogenesis studies show that oCS PEMs are more stable and superior to nCS PEMs in supporting cell adhesion and spreading as well as in presenting BMP‐2 to the cells. oCS PEMs are triggering more osteogenesis as proved by the quantitative real‐time polymerase chain reaction, immune and histochemical staining. These findings show that intrinsic cross‐linking in oCS/Col I multilayers provides a successful tool to control GFs delivery and subsequent cell differentiation which opens new opportunities in regenerative therapies of bone and other tissues.