Transcriptional profiling of CD133+ cells in coronary artery disease and effects of exercise on gene expression
Introduction
It is widely believed that dysfunctional endothelium, associated with reduced nitric oxide bioactivity, induces a variety of proinflammatory and proliferative responses contributing to progression of atherosclerosis and clinical expression of disease (1). Bone marrow (BM)-derived progenitor cells, first described in 1997 as CD34+ cells, are believed to play an important role in endothelial repair, as demonstrated in animal models of induced vascular injury (2). The markers VEGFR-2 (KDR) and CD133 were subsequently reported to define a population of particular relevance to vascular repair, as VEGFR-2 is expressed by endothelial cells and CD133 is only expressed on immature hematopoietic stem cells (3). These CD133+/VEGFR-2+ cells, although rare (<0.01% of mononuclear cells), circulate in peripheral blood and have the capacity to differentiate into cells with endothelial characteristics (4). Several groups have reported that BM-derived progenitor cells with endothelial differentiation potential are reduced in patients with coronary artery disease (CAD) (5., 6., 7.). We undertook the current study to test the hypothesis that in patients with CAD, CD133+ BM-derived progenitor cells have altered gene expression as a result of the co-morbidities of atherosclerosis, and that exercise, previously reported to increase BM-derived progenitor cells in circulation with improved endothelial characteristics (8., 9., 10., 11., 12., 13.), might favorably affect gene expression towards that seen in healthy subjects. To this end, we examined the global gene expression profiles of circulating CD133+ endothelial progenitor cells in CAD patients who participated in a 3-month exercise program. We report here for the first time that gene expression was significantly altered in CD133+ cells from CAD patients and demonstrate the reversal, by exercise, of some of these altered genes towards normal expression.
Section snippets
Methods
The CAD patients were enrolled in a cardiac rehabilitation program consisting of 36 sessions of 60 min each, spaced over approximately 3 months. Medical management was stable for at least 1 month prior to program participation and throughout the study all patients were maintained on their medications as prescribed, without change in preparation or dose. Cardiovascular examination and baseline testing were performed after an overnight fast (except for water), with blood samples drawn prior to
Clinical evaluation
Twenty-five CAD patients initially consented for protocol participation and completed the 3-month exercise program. For the group, fitness, as measured by treadmill exercise duration, was significantly improved following completion of the program, from 485 ± 159 to 555 ± 148 s (P = 0.0002). Numbers of CD133+ cells in blood increased from 873 ± 556 to 1666 ± 1747 cells/mL (P = 0.0384) following the exercise program.
Global gene expression analysis of CD133+ cells
Total RNA isolated from CD133+ cells derived from baseline and 3-month samples from patients
Discussion
There is considerable basic research and clinical interest in the relevance of BM-derived cells to vascular homeostasis and repair. Initial reports focused on hematopoietic progenitor cells with the CD34 marker, but subsequently included a population of immature progenitor cells indentified by the CD133 marker. The relevance of these progenitor cells in CAD was suggested by Werner et al. (17), who reported an inverse relation between CD34+ and CD133+ cells and subsequent cardiac events at 12
Acknowledgments
This research was supported by the Intramural Research Program of the NIH, National Heart, Lung and Blood Institute. We would like to acknowledge Ms Kimberly Woodhouse for her technical assistance in performing the QPCR assays.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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Authors who contributed equally to this study.