Therapeutic vasculogenesis. (top) Circulating EPCs may be harvested in analogous fashion to methods currently established for harvesting HSCs for autologous marrow transplantation. EPCs, purified and expanded ex vivo, may then be readministered, with or without angiogenic growth factors, to optimize therapeutic neovascularization. (middle) Harvested EPCs may be transfected ex vivo with genes encoding for proangiogenic factors. When incorporated into nascent vasculature, administered EPCs express growth-promoting factors directly at the site of, and thereby potentially augment, neovascularization. (bottom) If EPCs are transduced ex vivo with transgene encoding antitumorigenic factors, administered EPCs home to vascular infrastructure of developing neoplasm where they act as a “Trojan Horse” to express antiangiogenic factors that sabotage tumor growth and metastasis.