Objective Circulating CD34⁺CD45⁻ cell concentrations are increased in patients with coronary artery disease, however their pathophysiological significance is unknown. We determined CD34⁺CD45⁻ cell concentrations following percutaneous coronary intervention (PCI) in order to explore their role in acute vascular injury.

Methods In a prospective time-course analysis, we quantified using flow cytometry circulating CD34⁺CD45⁻ cells, traditional CD34⁺VEGFR-2⁺ putative endothelial progenitor cells (EPCs), CD14⁺ VEGFR⁻ 2⁺Tie-2⁺ angiogenic monocytes and intercellular adhesion molecule expression (CXCR-4 and CD18) in patients, before and during the first week following diagnostic angiography (n=13) or PCI (n=23). Vascular endothelial growth factor-A (VEGF-A) and C reactive protein (CRP) were quantified by ELISA.

Results Unlike diagnostic angiography, PCI increased circulating neutrophil and CRP concentrations at 24 and 48 h, respectively (p<0.002 for both). CD34⁺CD45⁻ cell concentrations were unaffected by angiography (p>0.4), but were transiently increased 6 h following PCI (median (IQR) 0.93 (0.43–1.49) vs 1.51 (0.96–2.15)×10⁶ cells/L; p=0.01), returning to normal by 24 h.

This occurred in the absence of any change in serum VEFG-A concentration, adhesion molecule expression on CD34⁺ cells, or mobilisation of traditional EPCs or angiogenic monocytes (p>0.1 for all).

Conclusions PCI transiently increases circulating CD34⁺CD45⁻ cells, without increasing CD34⁺ adhesion molecule expression or VEGF-A concentrations, suggesting that CD34⁺CD45⁻ cells may be mobilised from the vessel wall directly as a result of mechanical injury. Traditional putative EPC and angiogenic monocytes are unaffected by PCI, and are unlikely to be important in the acute response to vascular injury.