Endothelial and hematopoietic progenitor cells (EPCs and HPCs): hand in hand fate determining partners for cancer cells.

Tumor growth and metastasis need new vessel formation by angiogenesis provided by mature endothelial cells and postnatal vasculogenesis provided by endothelial progenitor cells (EPCs). Emerging data suggest a coordinated interaction between EPCs and hematopoietic progenitor cells (HPCs) in these processes. The complexity of the mechanisms governing the new vessel formation by postnatal vasculogenesis has increased by new evidence that not only bone marrow derived EPCs and HPCs seem to be involved in this process but also local progenitors residing within the vascular wall are mobilized and activated to new vessel formation by tumor cells. This review attempts to bring these systemic and local players of postnatal vasculogenesis together and to highlight their role in tumor growth and mestastasis.