Objective: The low number of circulating endothelial progenitor cells (EPCs) has emerged as a biomarker of cardiovascular (CV) risk in adults. Data regarding EPCs in paediatric populations with CV risk factors are limited. The aim of the study was to estimate the EPC number and its relationship with vascular function and structure in children with type 1 diabetes mellitus (T1DM).

Design and methods: We performed a comparative analysis of 52 children with T1DM (mean age 14.5 years; diabetes duration, 6.0 years; HbA1c level, 8.5%) and 36 healthy age- and gender-matched control children. EPCs were identified and analysed by flow cytometry with the use of MABs directed against CD34, CD144 (VE-cadherin) and CD309 (VEGFR-2). sICAM-1, hsCRP, thrombomodulin and adiponectin levels were also assessed. We evaluated vascular function (flow-mediated dilation (FMD)) and structure (carotid intima-media thickness (IMT)) ultrasonographically.

Results: Frequencies of CD34+ cells were similar in both groups (P=0.30). In contrast, frequencies of CD34+VE-cadherin+ cells were significantly higher in diabetic children compared with the healthy group (P=0.003). Similarly, diabetic patients tended to present with higher frequencies of CD34+VEGFR+ cells (P=0.06). FMD was lower (6.9 vs 10.5%, P=0.002) and IMT was higher (0.50 vs 0.44 mm, P=0.0006) in diabetic children. We demonstrated a significant relationship between CD34+VEGFR-2+ cells and BMI (r=0.3, P=0.014), HDL (r=-0.27, P=0.04), sICAM-1 (r=0.47, P=0.023) and FMD (r=-0.45, P<0.001). Similarly, frequencies of CD34+VE-cadherin+ cells were significantly correlated with BMI (r=0.32, P=0.02) and FMD (r=-0.31, P=0.03).

Conclusions: We demonstrated here that increased frequencies of EPCs observed in diabetic children are negatively correlated with endothelial function. Further studies are warranted to assess whether this phenomenon might result from effective mobilisation of EPCs in order to repair damaged endothelium in children at increased risk for atherosclerosis.