Biology and Potential Therapeutic Applications of Stem Cells

Tuesday, October 18, 2005 10:15 AM-12:00 PM Room No. 610/612
Chair(s): Greenberger, Joel

(SY032) Radiation-induced modulation of circulating endothelial progenitors.

Hlatky, Lynn*,1, 1 Vascular Biology Program, Boston, MA, USA

ABSTRACT- It is well established that bone-marrow-derived circulating endothelial progenitor cells (CEPs) play a role in tumor angiogenesis, thereby influencing tumor growth dynamics and vascular targeting. Recent studies further demonstrate that embryonic endothelial progenitor cells preferentially home to sites of lung metastases. Following local irradiation, circulating endothelial cells offer a systemic means by which tumor vasculature may be rescued. Circulating endothelial cells are sorted from other cells in the peripheral blood based on the differential expression of endothelial and hematopoietic cell markers. My lab has studied the kinetics of the circulating endothelial cell compartment (both progenitor and mature cells) in mouse models following whole-body irradiation (2-15Gy, 137Cs). Irradiation modulates the relative levels of these circulating endothelial cells in a time-dependent manner. Irradiation at the clinically relevant dose of 2Gy is found to increase the percentage of CEPs in the blood, which may impact post-treatment tumor repopulation. Findings from other laboratories on the radiation response characteristics of circulating endothelial progenitor cells will also be shown.

Key words: tumor growth dynamics, endothelial and hematopoietic cell markers, bone-marrow-derived circulating endothelial cells, tumor angiogenesis and vascular targeting

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2005 RRS