Presence of circulating endothelial progenitor cells and levels of stromal-derived factor-1α are associated with ascending aorta aneurysm size

Circulating endothelial progenitor cells (EPCs) are a specialized subset of stem/progenitor cells found in bone marrow. They participate in neo-vascularization of injured vessels and predict cardiovascular outcome in patient at risk. Several factors influence their migration and proliferation, among which is the widely studied stromal-derived factor-1α (SDF-1α). In cardiovascular disease, regarding thoracic aortic aneurysms (TAAs), few studies have investigated the levels of EPC and SDF-1α. As rupture, acute dissection and hematoma are acute complications of idiopathic ascending thoracic aortic aneurysm (iATAA) that increase with the size of aneurysm, we aimed to evaluate a potential relationship between circulating EPC and SDF-1α and iATAA size.The aneurysm size of 27 consecutive patients suffering from iATAA and scheduled for surgery was assessed by computed tomography scan. In all patients, we measured levels of circulating EPCs by flow cytometer, and plasma levels of SDF-1α the day before surgery.The median aneurysm size was 54 mm (interquartile range (IQR): 50.0-58.8]. The EPC levels of CD34+/CD144+/CD14- and CD34+/VEGF-R2+/CD14- were inversely correlated to aneurysm diameter (p = 0.038, r = -0.424 and p = 0.0046, r = -0.65, respectively) before surgery. Conversely, plasma levels of SDF-1α were positively correlated to aneurysm size (p = 0.042; r = 0.47).Our findings indicate that EPC levels may be useful for monitoring ascending aorta aneurysms and that SDF-1α could be a biomarker of iATAA expansion.