A review on macrophage responses to biomaterials.

Macrophages are the dominant infiltrating cells that respond rapidly to biomaterial implantation in soft and hard tissues. These cells and their fused morphologic variants, multinucleated giant cells or foreign body giant cells, usually remain at biomaterial-tissue interfaces for the lifetime of the device in vivo. As a component of the immune system, macrophage activities are closely related to immune responses, inflammation and foreign body responses. However, macrophages also mediate biodegradation of bioresorbable materials via phagocytosis and extracellular degradation. In addition, macrophages are essential for effective tissue regeneration as they regulate the recruitment, proliferation and differentiation of target cells, such as fibroblasts, osteoblasts, endothelial cells and keratinocytes during healing processes.