Circulating progenitor cells after cold pressor test in hypertensive and uremic patients

Endothelium was initially considered an inert lining of the blood vessels. Recently, it was suggested that damaged cells are continuously replaced by novel cells, hematopoietic stem cells (HSCs), which are directly mobilized by the bone marrow and then transformed into endothelial progenitor cells (EPCs). Initial triggers of vessel remodeling are physical forces such as blood pressure and fluid shear stress. We investigated whether or not a stress stimulus on vessels applied by a cold pressor test (CPT) would stimulate the mobilization of progenitor cells. Twenty-two healthy subjects, 20 patients with essential hypertension, and 18 with chronic kidney disease (CKD) underwent CPT by dipping their hands in icy water for 4 min. Immediately before and after 4 and 60 min, we quantified HSCs and EPCs identified by flow cytometry. We measured also adhesion soluble molecules (sICAM-1, sVCAM-1, and sE-selectin) as markers of endothelial activation. In healthy and hypertensive subjects, but not in CKD subjects, the number of HSCs was elevated as a direct response to CPT stress. Levels of EPCs and adhesion soluble molecules increased significantly, but to a different extent in every group. In CKD patients, the number of EPCs did not return to basal levels either after 60 min. Levels of adhesion soluble molecules directly correlated with the number of progenitor cells in hypertensive and healthy subjects. CPT caused an increase in adhesion soluble molecules. Discrepancies in the numbers of HSCs and EPCs in CKD patients could suggest a specific impairment in blood vessel remodeling correlated with recognized endothelial dysfunction.