Macrophage membrane-functionalized nanofibrous mats and their immunomodulatory effects on macrophage polarization

Immunomodulation is an important phenomenon in the normal mammalian host response toward an injury, and plays a critical role in tissue regeneration and regenerative medicine. Different phenotypes of macrophages show an array of activation states compassing pro-inflammatory to pro-alleviating cells, which are the critical players to modulate immune response and tissue regeneration. In this study, macrophage membranes of different phenotypes (macrophages (M0), classically activated macrophages (M1) and alternatively activated macrophages (M2)) were coated onto poly-ε-caprolactone (PCL) nanofibers to acquire exterior surface proteins and similar functions of the natural membranes. In vitro results unveiled that these nanofibers, especially the M2-PCL nanofibers, can suppress the activities of inflammatory markers such as TNF-α and IL-1β, and stimulate anti-inflammatory markers such as Arg-1, IL-10 and TGF-β. In a C57BL/6 mouse model, the macrophage membrane-coated nanofibers, especially the M2-PCL nanofibers, displayed minimal cellular infiltration and low collagen deposition, increased anti-inflammatory CD206 and decreased inflammatory CD86 levels. The M2-PCL nanofibers most effectively neutralized inflammatory chemokines, regulated the expression of inflammation-associated genes as well as anti-inflammatory genes, and showed strong immunomodulatory effects than the PCL, M0-PCL and M1-PCL nanofibers.