Numerical and functional impairment of circulating endothelial progenitor cells (EPCs) is thought to contribute to vascular aging and the associated increase in cardiovascular risk. We tested the following hypotheses: 1) EPC clonogenic and migratory capacity decrease progressively with age in healthy, sedentary adult men; and 2) regular aerobic exercise will improve EPC clonogenic and migratory capacity in previously sedentary middle-aged and older men. Peripheral blood samples were collected from 46 healthy sedentary men: 10 young (26 +/- 1 yr), 15 middle-aged (47 +/- 1 yr), and 21 older (63 +/- 1 yr). Mononuclear cells were isolated and preplated for 2 days, and nonadherent cells were further cultured for 7 days to determine EPC colony-forming units. Migratory activity of EPCs was determined using a modified Boyden chamber. Ten sedentary middle-aged and older men (59 +/- 3 yr) were studied before and after a 3-mo aerobic exercise intervention. The number of EPC colony-forming units was approximately 75% lower (P < 0.01) in middle-aged (12 +/- 3) and older (8 +/- 2) compared with young (40 +/- 7) men. There was no difference in colony count between middle-aged and older men. EPC migration (fluorescent units) was significantly reduced in older (453 +/- 72) compared with young (813 +/- 114) and middle-aged (760 +/- 114) men. The exercise intervention increased (P < 0.05) both EPC colony-forming units (10 +/- 3 to 22 +/- 5) and migratory activity (683 +/- 96 to 1,022 +/- 123) in previously sedentary middle-aged and older men. These results provide further evidence that aging adversely affects EPC function. Regular aerobic-endurance exercise, however, is an effective lifestyle intervention strategy for improving EPC clonogenic and migratory capacity in middle-aged and older healthy men.

. Endothelial t-PA release is impaired in overweight and obese adults but can be improved with regular aerobic exercise. Am J Physiol Endocrinol Metab 289: E807-E813, 2005. First published June 28, 2005; doi:10.1152/ajpendo.00072.2005.-Endothelial release of tissue-type plasminogen activator (t-PA) regulates fibrinolysis and is considered to be a primary endogenous defense mechanism against thrombosis. Adiposity is associated with an increased risk of atherothrombotic events. We determined the influence of overweight and obesity on the capacity of the vascular endothelium to release t-PA and the effects of regular aerobic exercise on endothelial t-PA release in previously sedentary overweight and obese adults. First, we studied 66 sedentary adults: 28 normal-weight (BMI Ͻ25 kg/m 2 ); 22 overweight (BMI Ն25 and Ͻ30 kg/m 2 ); and 16 obese (BMI Ն30 kg/m 2 ). Net endothelial t-PA release was determined in vivo in response to intrabrachial infusions of bradykinin (BK) and sodium nitroprusside. Second, we studied 17 overweight and obese adults who completed a 3-mo aerobic exercise intervention. Net release of t-PA in response to BK was ϳ45% lower (P Ͻ 0.01) in overweight (from 0.1 Ϯ 0.4 to 41.7 Ϯ 4.9 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 ) and obese (Ϫ0.1 Ϯ 0.6 to 47.7 Ϯ 5.2 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 ) compared with normal-weight (0.1 Ϯ 0.8 to 77.5 Ϯ 6.7 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 ) adults. There was no difference in t-PA release between the overweight and obese groups. Exercise training significantly increased t-PA release capacity in overweight and obese adults (from Ϫ0.3 Ϯ 0.5 to 37.1 Ϯ 4.9 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 before training vs. 1.0 Ϯ 0.9 to 65.4 Ϯ 6.3 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 after training) to levels comparable with those of their normal-weight peers. These results indicate that overweight and obesity are associated with profound endothelial fibrinolytic dysfunction. Importantly, however, regular aerobic exercise can increase the capacity of the endothelium to release t-PA in this at-risk population.endothelium; fibrinolysis; tissue-type plasminogen activator RECENT ESTIMATES INDICATE that over 60% of the adult population in the United States is either overweight or obese (21). Moreover, the incidence of overweight and obesity is highest in middle-aged and older adults and is thought to contribute to the increased risk of coronary artery disease, cerebrovascular disease, and atherothrombotic events in this segment of the population (37,39,40).It is now well accepted that endothelial dysfunction plays an important role in the initiation and progression of atherosclerosis (5, 45). A potential mechanism underlying the heightened atherothrombotic risk with obesity is impaired endothelial control of fibrinolysis. Endothelial cells are the principal site of synthesis and release of tissue-type plasminogen activator (t-PA), the key enzyme in initiating an endogenous fibrinolytic response, due to its ability to preferentially activate plasminogen on the surface of developing thrombi (15). Experimental...

Middle-aged women have a lower prevalence and incidence of cardiovascular events than men. The mechanisms responsible for this sex-specific difference are unclear. Numerical and functional impairment of bone marrow-derived circulating endothelial progenitor cells (EPCs) is associated with increased cardio-and cerebrovascular morbidity and mortality. It is currently unknown whether there are sex-related differences in EPC number and function in middle-aged adults. We tested the hypothesis that EPCs isolated from middle-aged women demonstrate greater colony forming capacity and migratory activity compared with men of similar age. Peripheral blood samples were collected from 50 sedentary adults; 25 men (age: 59±1 yr) and 25 women (58±1 yr). Mononuclear cells were isolated, preplated for 2 days and nonadherent cells were further cultured for 7 days to determine EPC colony forming units. Migratory activity of EPCs was determined using a modified Boyden chamber. The number of EPC colony forming units was significantly higher (∼150%) in samples collected from women (16±3) compared with men (7±1). In addition, EPC migration (relative fluorescent units) was ∼40% greater in women (729±74) versus men (530±67). These results demonstrate that EPC colony forming capacity and migratory activity are higher in middle-aged women compared with men. Keywordsendothelial progenitor cells; colony-forming units; migration Cardiovascular disease is the most frequent cause of death in both men and women. However, between the ages of 45 and 65 years, the prevalence of coronary heart disease and the incidence of myocardial infarction and stroke is ∼50% higher in men compared with women. The mechanisms responsible for this sex-related disparity are currently unclear. Interestingly, there are no apparent sex differences in the incidence and prevalence of traditional cardiovascular disease risk factors such as hypertension, obesity, tobacco use, hyperlipidemia, diabetes, or sedentary lifestyle in middle-aged adults 1 . Clinical interest in bone marrow-derived circulating endothelial progenitor cells as a novel vascular risk factor has increased due to their importance in vascular repair and noted inverse relation with endothelial dysfunction as well as cardiovascular and cerebrovascular disease 2-4 . Indeed, reduced EPC number and migratory activity have been linked to atherosclerotic disease progression and cardiovascular events This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptAm J Cardiol. Author manuscript; available in PMC 2008 January 1. NIH-PA Author ManuscriptNIH-PA Author Man...

Endothelial nitric oxide synthase (eNOS) activity has been shown to play a pivotal role in the mobilization of endothelial progenitor cells (EPCs) into the circulation from bone marrow. Indeed, in eNOS-deficient mice, exercise-induced EPC mobilization is severely diminished. We determined ex vivo whether circulating EPC colony-forming capacity and migratory activity are influenced by eNOS activity. Peripheral-blood mononuclear cells were isolated from 20 healthy adults and preplated for 2 days, and nonadherent cells were further cultured for 7 days in the presence and absence of N-nitro-L-arginine methyl ester (L-NAME, 300 microM, an eNOS antagonist) to determine EPC colony-forming units. Migratory activity of EPCs, cultured with and without L-NAME (300 microM) was determined by utilizing a modified Boyden chamber. The number of EPC colony-forming units was not significantly different when cultured in the absence or presence of L-NAME (21+/-5 vs 18+/-5). Moreover, eNOS inhibition did not alter EPC migratory activity; mean fluorescence was similar in samples cultured with (983+/-126 RFUs) and without (962+/-105 RFUs) L-NAME. These in vitro results suggest that, in contrast to EPC mobilization from the bone marrow, eNOS does not exert a modulatory influence on the functional capacity of circulating EPCs to either form colonies or migrate.