To the editor: In their interesting article Kim et al1 confirmed the beneficial action of granulocyte colony stimulating factor (G-CSF) administration on endothelial function as assessed by flow-mediated, endothelial-dependent dilatation of the brachial artery (FMD) in patients with an old or acute myocardial infarction (MI), despite a relative increase in C-reactive protein (CRP) levels. More specifically, in the group of patients with acute MI, there was a statistically significant increase of FMD after G-CSF administration while in those with old MI, FMD did not change significantly.

The authors suggested two possible explanations for the improvement in FMD: the direct effect of G-CSF on endothelial cells through the expression of G-CSF receptors on endothelial cells2 and its effect through the …