The interplay between macrophages and angiogenesis in development, tissue injury and regeneration

During organ development and remodeling, macrophages support angiogenesis, not only by secreting proangiogenic growth factors and matrix-remodeling proteases, but also by physically interacting with the sprouting vasculature to assist the formation of complex vascular networks. Recent data further indicate that embryonic and tumor-associated macrophages express similar genetic programs, possibly suggesting convergent functions in organogenesis and tumorigenesis. In this article, we review the role of macrophages in development, tissue injury and regeneration, by focusing on the mechanisms used by subsets of these cells, such as the TIE2-expressing macrophages, to regulate angiogenesis and lymphangiogenesis in both fetal and post-natal life.