Circulating endothelial progenitor cells in patients with unstable angina: association with systemic inflammation.

BACKGROUND: Endothelial progenitor cells (EPC) are present in peripheral blood and can develop a functional endothelial phenotype. The number and function of circulating EPCs are altered in atherosclerosis, diabetes, and after myocardial infarction and EPCs have been shown to promote postnatal angiogenesis and vasculogenesis. We investigated the number and adhesive properties of EPCs from patients with unstable angina and no evidence of cardiac necrosis. METHODS AND RESULTS: Patients were selected with unstable angina (n=29) and no evidence of cardiac necrosis, and controls with stable angina (n=12) and atherosclerotic risk factors, medication use, and coronary vessel involvement similar to patients. Circulating EPC numbers were determined by colony-forming unit assay and their adhesive properties were evaluated by EPC capacity to bind immobilised fibronectin. High-sensitivity C-reactive protein (hsCRP) was determined in all patients. Circulating EPCs were significantly increased in patients with unstable as compared with stable angina (24.5+/-2.6 vs. 13.3+/-2.9, respectively). Seven unstable angina patients followed up for 3 months after clinical stabilisation exhibited a reduction of close to 50% in circulating EPC numbers. The adhesive capacity of EPCs from patients with unstable and stable angina did not differ. A positive correlation was found between systemic CRP levels and circulating EPC numbers, but not their adhesive capacity. CONCLUSION: Patients with unstable angina and no evidence of cardiac necrosis exhibited increased circulating EPCs. Systemic inflammation, in addition to recognised growth factors, could play a role in the peripheral mobilisation of EPCs in patients with anginal syndromes.

Number and adhesive properties of circulating endothelial progenitor cells in patients with in-stent restenosis.

OBJECTIVE: Intact endothelialization machinery is essential to facilitate vessel healing after stent placement and to prevent restenosis. Circulating endothelial progenitor cells (EPC) have been demonstrated in the peripheral blood and shown to display endothelial functional properties, along with the ability to traffic to damaged vasculature. We reasoned that robust in-stent intimal growth could be partially related to impaired endothelialization resulting from reduced circulating EPC number or function. METHODS AND RESULTS: Sixteen patients with angiographically-demonstrated in-stent restenosis were compared with patients with a similar clinical presentation that exhibited patent stents (n=11). Groups were similar with respect to the use of drugs that could potentially influence EPC numbers. Circulating EPC numbers were determined by the colony-forming unit assay, and their phenotype was characterized by endothelial-cell markers. Adhesiveness of EPC from both groups to extracellular matrix and to endothelial cells was also assayed. Patients with in-stent restenosis and with patent stents displayed a similar number of circulating EPC. Fibronectin-binding was compromised in patients with in-stent restenosis as compared with their controls exhibiting patent stents. Patients with diffuse in-stent restenosis exhibited reduced numbers of EPC in comparison with subjects with focal in-stent lesions. CONCLUSIONS: Reduced numbers of circulating EPC in patients with diffuse in-stent restenosis and impaired adhesion of EPC from patients with restenosis provides a potential mechanism mediating the exuberant proliferative process. These markers, if further validated, could provide means of risk stratifying patients for likelihood of developing in-stent restenosis.

Evidence that nitric oxide regulates cell-cycle progression in the developing chick neuroepithelium.

In all developing epithelia, the nuclei continually migrate between the apical and basal sides of the cell during the cell cycle, with S phase occurring basally and mitosis occurring apically. The purpose and mechanism of this nuclear migration are unknown. Here, we show that nitric oxide (NO) is endogenously produced in the developing chicken neural tube, where it apparently regulates cell-cycle progression. We provide evidence that high NO levels promote entry into S phase basally, whereas low levels of NO facilitate entry into mitosis apically.