Covalent linkage of sulfated hyaluronan to the collagen scaffold Mucograft® enhances scaffold stability and reduces proinflammatory macrophage activation in vivo

Sulfated glycosaminoglycans(sGAG)show interaction with biological mediator proteins.Although collagen-based biomaterials are widely used in clinics,their combination with high-sulfated hyaluronan(sHA3)is unexplored.This study aims to functionalize a collagen-based scaffold(Mucograft®)with sHA3 via electrostatic(sHA3/PBS)or covalent binding to collagen fibrils(sHA3+EDC/NHS).Crosslinking without sHA3 was used as a control(EDC/NHS Ctrl).The properties of the sHA3-functionalized materials were characterized.In vitro growth factor and cytokine release after culturing with liquid platelet-rich fibrin was performed by means of ELISA.The cellular reaction to the biomaterials was analyzed in a subcutaneous rat model.The study revealed that covalent linking of sHA3 to collagen allowed only a marginal release of sHA3 over 28 days in contrast to electrostatically bound sHA3.sHA3+EDC/NHS scaffolds showed reduced vascular endothelial growth factor(VEGF),transforming growth factor beta 1(TGF-β1)and enhanced interleukin-8(IL-8)and epithelial growth factor(EGF)release in vitro compared to the other scaffolds.Both sHA3/PBS and EDC/NHS Ctrl scaffolds showed a high proinflammatory reaction(M1:CD-68+/CCR7+)and induced multinucleated giant cell(MNGC)formation in vivo.Only sHA3+EDC/NHS scaffolds reduced the proinflammatory macrophage M1 response and did not induce MNGC formation during the 30 days.SHA3+EDC/NHS scaffolds had a stable structure in vivo and showed sufficient integration into the implantation region after 30 days,whereas EDC/NHS Ctrl scaffolds underwent marked disintegration and lost their initial structure.In summary,functionalized collagen(sHA3+EDC/NHS)modulates the inflammatory response and is a promising biomaterial as a stable scaffold for full-thickness skin regeneration in the future.