Glycosaminoglycan - biohybrid hydrogels for the immune modulation in wound healing

Abstract

Event Abstract Back to Event Glycosaminoglycan - biohybrid hydrogels for the immune modulation in wound healing Lucas Schirmer1, Uwe Freudenberg1 and Carsten Werner1, 2 1 Leibniz-Institut für Polymerforschung Dresden, Max Bergmann Center of Biomaterials, Germany 2 Technische Universität Dresden, Center for Regenerative Therapies Dresden (CRTD), Germany Introduction: Chronic wounds represent a challenge for conventional wound treatment. The underlying dysregulation of inflammatory signals can lead to a severe impairment of the tissue regeneration. In this pathogenic state, the inflammatory phase of wound healing is prolonged due to the massive production of inflammatory cytokines in the surrounding tissue. To address these severe problem, novel materials for the targeted treatment of severely inflamed wounds are urgently needed. Therefore we developed a modular starPEG-glycosaminoglycan (GAG) hydrogel[1], that efficiently administrate the anti-inflammatory interleukins 4 and 10. The high GAG content of the matrix in particular is the key for the protection and sustained release of both cytokines, which are crucial for the resolvement of inflammation and the support of regenerative processes during wound healing[2],[3]. In here, we show the ability of the versatile IL4 and 10 releasing hydrogel matrix to decrease the inflammatory response of immune cells and to induce their regenerative polarization. Materials and Methods: Well defined hydrogels were formed through Michael addition crosslinking of a four-arm poly(ethylene glycol) and the GAG heparin while IL4 and IL10 were non-covalently conjugated through electrostatic interaction to the heparin (Fig. 1 A/B). The release of both interleukins was characterized in medium supplemented with 0.1% BSA utilizing ELISA-techniques. Consequently, the effects of IL4- and IL10-loaded hydrogels were tested on primary macrophages challenged with bacterial LPS. The amount of inflammatory factors released were measured by multiplex analysis and the gene expression was analyzed by rt-PCR. Finally, the materials were tested in vivo by implanting preformed hydrogel discs in 4 mm back skin wounds of 8 week old mice. Results and Discussion: The starPEG GAG hydrogel platform showed a tunable and sustained release over at least 168h (Fig. 1 B). Furthermore, the released amount of both cytokines could be independently adjusted through the variation of the initial loading concentration. IL10 functionalized hydrogels effectively suppressed the inflammatory response of macrophages in vitro (Fig. 2 A). While the IL-4 loaded materials did not influence the amount of inflammatory factors released, they induced the regenerative response of macrophages indicated by the marker genes Arg1 and Ym1 (Fig.2 B). Moreover, IL4-loaded hydrogels induced collagen I/III deposition of primary dermal fibroblasts. Interestingly, the application of hydrogels functionalized with a combination of IL4 and IL10 result in the decrease of the inflammatory response as well as the increase of pro-regenerative behavior of macrophages. In line with this, we found a decreased invasion of immune cells to the wound if the hydrogels were transplanted in a murine model. Conclusion: The starPEG-GAG hydrogels can be utilized for the sustained release of multiple anti-inflammatory cytokines for relevant time periods. They effectively decrease the inflammatory response and promote the regenerative behavior in macrophages and fibroblast, two cell types essential in the control of wound healing. In essence, the in here introduced IL4- and IL10-functionalized biohybrid hydrogels are very promising as novel wound dressings capable for the regulation of chronically inflamed wounds. This work was supported by the Deutsche Forschungsgemeinschaft (SFB-TR67).