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Major problems with biomedical devices in particular implants located in nonsterile environments concern: (i) excessive immune response to the implant, (ii) development of bacterial biofilms, and (iii) yeast and fungi infections. An original multifunctional coating that addresses all these issues concomitantly is developed. A new exponentially growing polyelectrolyte multilayer film based on polyarginine (PAR) and hyaluronic acid (HA) is designed. The films have a strong inhibitory effect on the production of inflammatory cytokines released by human primary macrophage subpopulations. This could reduce potential chronic inflammatory reaction following implantation. Next, it is shown that PAR, due to its positive charges, has an antimicrobial activity in film format against Staphylococcus aureus for 24 h. In order to have a long-term antimicrobial activity, a precursor nanoscale silver coating is deposited on the surface before adding the PAR/HA films. Moreover, the PAR/HA films can be easily further functionalized by embedding antimicrobial peptides, like catestatin (CAT), a natural host defense peptide. This PAR/HA+CAT film proves to be effective as an antimicrobial coating against yeast and fungi and its cytocompatibility is also assessed. Finally, this all-in-one system constitutes an original strategy to limit inflammation and prevents bacteria, yeast, and fungi infections.

The immediate tissue microenvironment of implanted biomedical devices and engineered tissues is highly influential on their long term fate and efficacy. The creation of a long-term anti-inflammatory microenvironment around implants and artificial tissues can facilitate their integration. Macrophages are highly plastic cells that define the tissue reactions on the implanted material. Local control of macrophage phenotype by long-term fixation of their healing activities and suppression of inflammatory reactions are required to improve implant acceptance. Herein, we describe the development of a cytokine cocktail (M2Ct) that induces stable M2-like macrophage phenotype with significantly decreased pro-inflammatory cytokine and increased anti-inflammatory cytokine secretion profile. The positive effect of the M2Ct was shown in an in vitro wound healing model; where M2Ct facilitated wound closure by human fibroblasts in co-culture conditions. Using a model for induction of inflammation by LPS we have shown that the M2Ct phenotype is stable for 12days. However, in the absence of M2Ct in the medium macrophages underwent rapid pro-inflammatory re-programming upon IFNg stimulation. Therefore, loading and release of the cytokine cocktail from a self-standing, transferable gelatin/tyraminated hyaluronic acid based release system was developed to stabilize macrophage phenotype for in vivo applications in implantation and tissue engineering. The M2Ct cytokine cocktail retained its anti-inflammatory activity in controlled release conditions. Our data indicate that the direct application of a potent M2 inducing cytokine cocktail in a transferable release system can significantly improve the long term functionality of biomedical devices by decreasing pro-inflammatory cytokine secretion and increasing the rate of wound healing.Uncontrollable activation of macrophages in the microenvironment of implants and engineered tissues is a significant problem leading to poor integration of implants and artificial tissues. In the current manuscript we demonstrate that self-standing, transferable gelatin/tyraminated hyaluronic acid based thin films are perspective tools for controlled release of anti-inflammatory cytokine combinations and can be used to down-modulate macrophage activation on implant surfaces. We also show that optimized cytokine cocktail consisting of IL4/IL10/TGFβ1 (M2Ct) induces long-term anti-inflammatory and pro-healing phenotype in human primary monocyte-derived macrophages. This cocktail formulation could be loaded on gelatin/tyraminated films and promoted favorable M2-like macrophage phenotype with low responsiveness to pro-inflammatory stimuli. Such self-standing release systems can be used for prolonged local control of macrophage phenotype upon implantation.

Implants, transplants, and implantable biomedical devices are mainstream solutions for a wide variety of human pathologies. One of the persistent problems around nondegradable metallic and polymeric implants is failure of macrophages to resolve the inflammation and their tendency to stay in a state, named “frustrated phagocytosis.” During the initial phase, proinflammatory macrophages induce acute reactions to trauma and foreign materials, whereas tolerogenic anti-inflammatory macrophages control resolution of inflammation and induce the subsequent healing stage. However, implanted materials can induce a mixed pro/anti-inflammatory phenotype, supporting chronic inflammatory reactions accompanied by microbial contamination and resulting in implant failure. Several materials based on natural polymers for improved interaction with host tissue or surfaces that release anti-inflammatory drugs/bioactive agents have been developed for implant coating to reduce implant rejection. However, no definitive, long-term solution to avoid adverse immune responses to the implanted materials is available to date. The prevention of implant-associated infections or chronic inflammation by manipulating the macrophage phenotype is a promising strategy to improve implant acceptance. The immunomodulatory properties of currently available implant coatings need to be improved to develop personalized therapeutic solutions. Human primary macrophages exposed to the implantable materials ex vivo can be used to predict the individual’s reactions and allow selection of an optimal coating composition. Our review describes current understanding of the mechanisms of macrophage interactions with implantable materials and outlines the prospects for use of human primary macrophages for diagnostic and therapeutic approaches to personalized implant therapy.

Polylactic acid (PLA) based implants can cause inflammatory complications. Macrophages are key innate immune cells that control inflammation. To provide higher biocompatibility of PLA-based implants with local innate immune cells their surface properties have to be improved. In our study surface modification technique for high-molecular PLA (MW=1,646,600g/mol) based biomaterials was originally developed and successfully applied. Optimal modification conditions were determined. Treatment of PLA films with toluene/ethanol=3/7 mixture for 10min with subsequent exposure in 0.001M brilliant green dye (BGD) solution allows to entrap approximately 10(-9)mol/cm(2) model biomolecules. The modified PLA film surface was characterized by optical microscopy, SERS, FT-IR, UV and TG/DTA/DSC analysis. Tensile strain of modified films was determined as well. The effect of PLA films modified with BGD on the inflammatory reactions of primary human monocyte-derived macrophages was investigated. We developed in vitro test-system by differentiating primary monocyte-derived macrophages on a coating material. Type 1 and type 2 inflammatory cytokines (TNFα, CCL18) secretion and histological biomarkers (CD206, stabilin-1) expression were analyzed by ELISA and confocal microscopy respectively. BGD-modified materials have improved thermal stability and good mechanical properties. However, BGD modifications induced additional donor-specific inflammatory reactions and suppressed tolerogenic phenotype of macrophages. Therefore, our test-system successfully demonstrated specific immunomodulatory effects of original and modified PLA-based biomaterials, and can be further applied for the examination of improved coatings for implants and identification of patient-specific reactions to implants.