Figure 6. Proposed mechanism for the role of PTK7+VEGFR2+ mononuclear cells in angiogenesis.
PTK7 expression by mononuclear cells is necessary for VEGFR2 acquisition in bone marrow and peripheral blood. These PTK7+VEGFR2+ mononuclear cells migrate to angiogenic sites where they promote angiogenesis by up-regulating ANG-1 secretion. Given their topographic localization and expression markers, they likely function in stabilizing blood vessel formation and/or have EPC potential.