Application of polychromatic flow cytometry to identify novel subsets of circulating cells with angiogenic potential

Abstract

Defining whether human circulating proangiogenic cells represent a subset of the hematopoietic system and express CD45 or are hematopoietic derivatives that do not express CD45 (and are called endothelial progenitor cells) remains controversial. We have previously developed a polychromatic flow cytometry (PFC) protocol to isolate subsets of hematopoietic cells and we now identify the circulating pool of CD34⁺CD45^dim cells representing functional circulating hematopoietic stem and progenitor cells (CHSPCs) that can be separated on the basis of AC133 expression and report that the AC133⁺ subset of the CHSPCs enhances the growth of tumor blood vessels in vivo in immunodeficient mice. In addition, the ratio of AC133⁺ proangiogenic CHSPCs to AC133⁻ nonangiogenic CHSPCs unambiguously correlates with the severity of the clinical state of patients with peripheral arterial disease. In sum, a PFC protocol validated via in vitro and in vivo analyses, can be used to interrogate the roles of human hematopoietic elements in the growth and maintenance of the vasculature. © 2010 International Society for Advancement of Cytometry