Abstract

Successful application of biomaterials for wound healing requires extracellular matrix components capable of promoting endogenous regeneration. Macrophages are a type of monocyte that play a critical role in tissue regeneration and repair. In the early phases of wound healing, these cells orchestrate the inflammatory response, and in the later stages of wound healing, they mediate the resolution of wound healing. In chronic wounds, uncontrolled macrophage activation negatively impacts the wound healing process. The purpose of this study was to characterize the effect of a decellularized, dehydrated human amniotic membrane (DDHAM) on macrophage differentiation and activation from monocytes in vitro. Monocytes were isolated from the peripheral blood of healthy donors and cultured on standard tissue culture plates (CB), collagen type I-coated plates (COL), and on plates containing DDHAM. Proinflammatory (M1) macrophage differentiation was modeled by monocyte culture in the presence of granulocytemacrophage colony-stimulating factor (GM-CSF) and activation with a strong pro-inflammatory cocktail, consisting of lipopolysaccharide (LPS) and interferon gamma (IFN-ɣ). The results showed that DDHAM enhanced monocyte differentiation in comparison with CB or COL as evident by increased cell size, viability, macrophage gene expression,and soluble factor secretion. Furthermore, macrophages differentiated on DDHAM and activated by inflammatory signals (LPS and IFN-ɣ) were impaired in their expression of a subset of LPS-inducible nuclear factor kappa-lightchain-enhancer of activated B cells target genes, with IL12β, coding for IL12p40 (subunit of IL12/23) being the most downregulated (p < 0.001). The effects of DDHAM on monocyte differentiation were found to be dependent upon β2 integrins. For the first time, these results indicate that a DDHAM can modulate macrophage behavior, by promoting their polarization into M2 phenotype, which is implicated in mediating a regenerative response and the resolution of healing, in a manner that is consistent with promoting vascular remodeling and tissue healing.