Iraj Hesaroieh

Circulating Progenitor Cells Identify Peripheral Arterial Disease in Patients With Coronary Artery Disease

RATIONALE Peripheral arterial disease (PAD) is a clinical manifestation of extracoronary atherosclerosis. Despite sharing the same risk factors, only 20% to 30% of patients with coronary artery disease (CAD) develop PAD. Decline in the number of bone marrow-derived circulating progenitor cells (PCs) is thought to contribute to the pathogenesis of atherosclerosis. Whether specific changes in PCs differentiate patients with both PAD and CAD from those with CAD alone is unknown. OBJECTIVE Determine whether differences exist in PCs counts of CAD patients with and without known PAD. METHODS AND RESULTS 1497 patients (mean age: 65 years; 62% men) with known CAD were identified in the Emory Cardiovascular Biobank. Presence of PAD (n=308) was determined by history, review of medical records, or imaging and was classified as carotid (53%), lower extremity (41%), upper extremity (3%), and aortic disease (33%). Circulating PCs were enumerated by flow cytometry. Patients with CAD and PAD had significantly lower PC counts compared with those with only CAD. In multivariable analysis, a 50% decrease in cluster of differentiation 34 (CD34+) or CD34+/vascular endothelial growth factor receptor-2 (VEGFR2+) counts was associated with a 31% (P=0.032) and 183% (P=0.002) increase in the odds of having PAD, respectively. CD34+ and CD34+/VEGFR2+ counts significantly improved risk prediction metrics for prevalent PAD. Low CD34+/VEGFR2+ counts were associated with a 1.40-fold (95% confidence interval, 1.03-1.91) and a 1.64-fold (95% confidence interval, 1.07-2.50) increases in the risk of mortality and PAD-related events, respectively. CONCLUSIONS PAD is associated with low CD34+ and CD34+/VEGFR2+ PC counts. Whether low PC counts are useful in screening for PAD needs to be investigated.

Progenitor Cells and Clinical Outcomes in Patients With Heart Failure

Background Endogenous regenerative capacity, assessed as circulating progenitor cell (PC) numbers, is an independent predictor of adverse outcomes in patients with cardiovascular disease. However, their predictive role in heart failure (HF) remains controversial. We assessed the relationship between the number of circulating PCs and the pathogenesis and severity of HF and their impact on incident HF events. Methods and Results We recruited 2049 adults of which 651 had HF diagnosis. PCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34, CD133, vascular endothelial growth factor receptor-2, and chemokine (C-X-C motif) receptor 4 epitopes. PC subsets were lower in number in HF and after adjustment for clinical characteristics in multivariable analyses, a low CD34+ and CD34+/CXCR+ cell count remained independently associated with a diagnosis of HF (P<0.01). PC levels were not significantly different in reduced versus preserved ejection fraction patients. In 514 subjects with HF, there were 98 (19.1%) all-cause deaths during a 2.2±1.5-year follow-up. In a Cox regression model adjusting for clinical variables, hematopoietic-enriched PCs (CD34+, CD34+/CD133+, and CD34+/CXCR4+) were independent predictors of all-cause death (hazard ratio 2.0, 1.6, 1.6-fold higher mortality, respectively; P<0.03) among HF patients. Endothelial-enriched PCs (CD34+/VEGF+) were independent predictors of mortality in patients with HF with preserved ejection fraction only (hazard ratio, 5.0; P=0.001). Conclusions PC levels are lower in patients with HF, and lower PC counts are strongly and independently predictive of mortality. Strategies to increase PCs and exogenous stem cell therapies designed to improve regenerative capacity in HF, especially, in HF with preserved ejection fraction, need to be further explored.

Bioactive Lipids and Circulating Progenitor Cells in Patients with Cardiovascular Disease

Bone marrow‐derived progenitor cells are mobilized into the peripheral blood after acute myocardial injury and in chronic ischemic heart disease. However, the mechanisms responsible for this mobilization are poorly understood. We examined the relationship between plasma levels of bioactive lipids and number of circulating progenitor cells (CPCs) in patients (N = 437) undergoing elective or emergent cardiac catheterization. Plasma levels of sphingosine‐1 phosphate (S1P) and ceramide‐1 phosphate (C1P) were quantified using mass spectrometry. CPCs were assessed using flow cytometry. S1P levels correlated with the numbers of CD34+, CD34+/CD133+, and CD34+/CXCR4+ CPCs even after adjustment for potential confounding factors. However, no significant correlation was observed between C1P levels and CPC count. Plasma levels of S1P correlated with the number of CPCs in patients with coronary artery disease, suggesting an important mechanistic role for S1P in stem cell mobilization. The therapeutic effects of adjunctive S1P therapy to mobilize endogenous stem cells need to be investigated. Stem Cells Translational Medicine 2017;6:731–735

Sex Differences in Circulating Progenitor Cells

Background Lower levels of circulating progenitor cells (PCs) reflect impaired endogenous regenerative capacity and are associated with aging, vascular disease, and poor outcomes. Whether biologic sex and sex hormones influence PC numbers remains a subject of controversy. We sought to determine sex differences in circulating PCs in both healthy persons and patients with coronary artery disease, and to determine their association with sex hormone levels. Methods and Results In 642 participants (mean age 48 years, 69% women, 23% black) free from cardiovascular disease, we measured circulating PC counts as CD45med+ mononuclear cells coexpressing CD34 and its subsets expressing CD133, chemokine (C‐X‐C motif) receptor 4, and vascular endothelial growth factor receptor 2 epitopes using flow cytometry. Testosterone and estradiol levels were measured. After adjustment for age, cardiovascular risk factors, and body mass, CD34+ (β=−23%, P<0.001), CD34+/CD133+ (β=−20%, P=0.001), CD34+/chemokine (C‐X‐C motif) receptor 4–positive (β=−24%, P<0.001), and CD34+/chemokine (C‐X‐C motif) receptor 4–positive/CD133+ (β=−21%, P=0.001) PC counts, but not vascular endothelial growth factor receptor 2‐positive PC counts were lower in women compared with men. Estradiol levels positively correlated with hematopoietic, but not vascular endothelial growth factor receptor 2‐ positive PC counts in women (P<0.05). Testosterone levels and PC counts were not correlated in men. These findings were replicated in an independent cohort with prevalent coronary artery disease. Conclusions Women have lower circulating hematopoietic PC levels compared with men. Estrogen levels are modestly associated with PC levels in women. Since PCs are reflective of endogenous regenerative capacity, these findings may at least partly explain the rise in adverse cardiovascular events in women with aging and menopause.

Progenitor Cells and Clinical Outcomes in Patients with Acute Coronary Syndromes

Rationale: Circulating progenitor cells (CPCs) mobilize in response to ischemic injury, but their predictive value remains unknown in acute coronary syndrome (ACS). Objective: We aimed to investigate the number of CPCs in ACS compared with those with stable coronary artery disease (CAD), relationship between bone marrow PCs and CPCs, and whether CPC counts predict mortality in patients with ACS. Methods and Results: In 2028 patients, 346 had unstable angina, 183 had an acute myocardial infarction (AMI), and the remaining 1499 patients had stable CAD. Patients with ACS were followed for the primary end point of all-cause death. CPCs were enumerated by flow cytometry as mononuclear cells expressing a combination of CD34+, CD133+, vascular endothelial growth factor receptor 2+, or chemokine (C-X-C motif) receptor 4+. CPC counts were higher in subjects with AMI compared those with stable CAD even after adjustment for age, sex, race, body mass index, renal function, hypertension, diabetes mellitus, hyperlipidemia, and smoking; CD34+, CD34+/CD133+, CD34+/CXCR4+, and CD34+/VEGFR2+ CPC counts were 19%, 25%, 28%, and 142% higher in those with AMI, respectively, compared with stable CAD. There were strong correlations between the concentrations of CPCs and the PC counts in bone marrow aspirates in 20 patients with AMI. During a 2 (interquartile range, 1.31–2.86)-year follow-up period of 529 patients with ACS, 12.4% died. In Cox regression models adjusted for age, sex, body mass index, heart failure history, estimated glomerular filtration rate, and AMI, subjects with low CD34+ cell counts had a 2.46-fold (95% confidence interval, 1.18–5.13) increase in all-cause mortality, P=0.01. CD34+/CD133+ and CD34+/CXCR4+, but not CD34+/VEGFR2+ PC counts, had similar associations with mortality. Results were validated in a separate cohort of 238 patients with ACS. Conclusions: CPC levels are significantly higher in patients after an AMI compared with those with stable CAD and reflect bone marrow PC content. Among patients with ACS, a lower number of hematopoietic-enriched CPCs are associated with a higher mortality.

Circulating Progenitor Cells and Racial Differences: A Possible Contribution to Health Disparity

Rationale: Blacks compared with whites have a greater risk of adverse cardiovascular outcomes. Impaired regenerative capacity, measured as lower levels of circulating progenitor cells (CPCs), is a novel determinant of adverse outcomes; however, little is known about racial differences in CPCs. Objective: To investigate the number of CPCs, PC-mobilizing factors, PC mobilization during acute myocardial infarction and the predictive value of CPC counts in blacks compared with whites. Methods and Results: CPCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34+, CD133+, VEGF2R+, and CXCR4+ epitopes in 1747 subjects, mean age 58.4±13, 55% male, and 26% self-reported black. Patients presenting with acute myocardial infarction (n=91) were analyzed separately. Models were adjusted for relevant clinical variables. SDF-1&agr; (stromal cell-derived factor-1&agr;), VEGF (vascular endothelial growth factor), and MMP-9 (matrix metallopeptidase-9) levels were measured (n=561), and 623 patients were followed for median of 2.2 years for survival analysis. Blacks were younger, more often female, with a higher burden of cardiovascular risk, and lower CPC counts. Blacks had fewer CD34+ cells (−17.6%; [95% confidence interval (CI), −23.5% to −11.3%]; P<0.001), CD34+/CD133+ cells (−15.5%; [95% CI, −22.4% to −8.1%]; P<0.001), CD34+/CXCR4+ cells (−17.3%; [95% CI, −23.9% to −10.2%]; P<0.001), and CD34+/VEGF2R+ cells (−27.9%; [95% CI, −46.9% to −2.0%]; P=0.04) compared with whites. The association between lower CPC counts and black race was not affected by risk factors or cardiovascular disease. Results were validated in a separate cohort of 411 patients. Blacks with acute myocardial infarction had significantly fewer CPCs compared with whites (P=0.02). Blacks had significantly lower plasma MMP-9 levels (P<0.001) which attenuated the association between low CD34+ and black race by 19% (95% CI, 13%–33%). However, VEGF and SDF-1&agr; levels were not significantly different between the races. Lower CD34+ counts were similarly predictive of mortality in blacks (hazard ratio, 2.83; [95% CI, 1.12–7.20]; P=0.03) and whites (hazard ratio, 1.79; [95% CI, 1.09–2.94]; P=0.02) without significant interaction. Conclusions: Black subjects have lower levels of CPCs compared with whites which is partially dependent on lower circulating MMP-9 levels. Impaired regenerative capacity is predictive of adverse outcomes in blacks and may partly account for their increased risk of cardiovascular events.

CENTRAL OBESITY PREDICTS CIRCULATING PROGENITOR CELL LEVELS

Background: Obesity is a pro-inflammatory state leading to endothelial cell injury and dysfunction. In particular, central (android) obesity is associated with increased cardiovascular disease risk. Bone marrow derived CD34+ progenitor cells (PC) levels are elevated in patients with high body mass

ASSOCIATION BETWEEN CIRCULATING PROGENITOR CELLS AND OUTCOMES IN PATIENTS WITH CORONARY ARTERY DISEASE

Background: Circulating hematopoietic enriched progenitor cells (PCs) predict adverse cardiovascular outcomes in patients with coronary artery disease (CAD). The additive predictive role of endothelial enriched PCs expressing vascular endothelial growth factor receptor (VEGF) remains controversial.

VITAMIN D3 LEVELS MODULATE CXCR4+ CIRCULATING PROGENITOR CELL COUNTS

The role of 1,25-dihydroxy-vitamin D3 (VitD3) in cardiovascular disease remains controversial. Vitamin D receptors on progenitor cells (PCs) promote maturation and vascular repair by inducing SDF1 expression and homing of CXCR4+ angiogenic myeloid cells. Whether VitD3 levels modulate circulating PCs

HIGH-SENSITIVITY TROPONIN-I LEVELS PREDICT LONG-TERM MORTALITY INDEPENDENT OF CORONARY ARTERY DISEASE SEVERITY

High-sensitivity Troponin-I (hs-TnI) as a marker of myocardial injury is predictive of adverse outcomes in patients with coronary artery disease (CAD). Whether the relationship between hs-TnI and outcomes is dependent on underlying CAD severity is unknown. 2826 patients without AMI (mean age 62, 64