Reproducibility of circulating endothelial cell enumeration and activation in children and adolescents.

Introduction: We examined the reproducibility of circulating endothelial cells (CEC) enumeration and activation among youth. Materials & methods: CECs from 151 youth were measured at baseline and 1 week follow-up. Enumeration of CEC in fresh whole blood was determined by direct assessment of buffy coat smears (CD146+ nucleated cells) and activated CEC (%VCAM-1 expression) was determined after immunomagnetic enrichment and co-staining of nuclei, plus positivity for P1H12 and VCAM-1. Results: No statistically significant difference in CEC enumeration (1.2 +/- 2.5 vs 1.3 +/- 2.2 CEC/milliliter of whole blood, p = 0.745) or activated CEC (57.1 +/- 24.4 vs 58.0 +/- 21.3 % VCAM-1, p = 0.592) between baseline and 1 week follow-up. Conclusion: On a cohort basis, CEC enumeration and activation are reproducible in youth. Relatively high individual biological variability may limit its clinical utility.