Circulating endothelial cells in patients with acute myeloid leukemia

Objectives: The circulating endothelial cells (CEC) are proposed to be a non-invasive marker of angiogenesis. The level of CEC in peripheral blood (PB) of acute myeloid leukemia (AML) patients has not been investigated prior to this study. We evaluated the count of resting (rCEC), activated (aCEC) and endothelial progenitor cells (CEPC) in the PB of AML and healthy subjects. In addition we correlated the levels of CEC with disease status, known prognostic factors and response to treatment. Methods: CEC were quantified by utilizing four-color flow cytometry procedures in 48 AML patients at the time of diagnosis and 29 healthy controls. Additionally, measurements were again taken after the first course of induction treatment in 12 of the patients. Results: The numbers of aCEC, rCEC and CEPC were significantly higher in the AML patients than in the controls ( P < 0.0001, P < 0.0001 and P < 0.001, respectively). The CEC count was significantly higher in the AML patients with white blood cell count ( WBC) > 15 G/L, elevated lactic dehydrogenase (LDH) levels and a higher ( over median) absolute blasts count (ABC) in PB than in the group with WBC < 15 G/L ( P < 0.03), a normal LDH level ( P < 0.03) and a lower (< median) ABC ( P < 0.05). The levels of aCEC, rCEC and CEPC determined after the first course of chemotherapy were significantly lower than at diagnosis in the patients who achieved complete remission ( P < 0.02), and do not differ in patients refractory to treatment. Conclusion: CEC levels are higher in AML and correlate with disease status and response to treatment. Further investigation should be undertaken to better determine their prognostic value.