Coronary endothelial dysfunction in humans is associated with coronary retention of osteogenic endothelial progenitor cells

Coronary Artery Calcification: Current Concepts and Clinical Implications

Coronary artery calcification (CAC) accompanies the development of advanced atherosclerosis. Its role in atherosclerosis holds great interest because the presence and burden of coronary calcification provide direct evidence of the presence and extent of coronary artery disease; furthermore, CAC predicts future events independently of concomitant conventional cardiovascular risk factors and to a greater extent than any other noninvasive biomarker of this disease. Nevertheless, the relationship between CAC and the susceptibility of a plaque to provoke a thrombotic event remains incompletely understood. This review summarizes the current understanding and literature on CAC. It outlines the pathophysiology of CAC and reviews laboratory, histopathological, and genetic studies, as well as imaging findings, to characterize different types of calcification and to elucidate their implications. Some patterns of calcification such as microcalcification portend increased risk of rupture and cardiovascular events and may improve prognosis assessment noninvasively. However, contemporary computed tomography cannot assess early microcalcification. Limited spatial resolution and blooming artifacts may hinder estimation of degree of coronary artery stenosis. Technical advances such as photon counting detectors and combination with nuclear approaches (eg, NaF imaging) promise to improve the performance of cardiac computed tomography. These innovations may speed achieving the ultimate goal of providing noninvasively specific and clinically actionable information.

The associations of markers of endothelial dysfunction with hip fracture risk

Endothelial dysfunction underlies the development of atherosclerotic vascular disease, which in turn is associated with osteoporotic fractures. Here, we examined the association of two markers of endothelial dysfunction with incident hip fracture risk in older adults but found no statistically significant associations between them.

PURPOSE/INTRODUCTION

Endothelial dysfunction underlies the development of atherosclerotic vascular disease. Vascular disease, in turn, is associated with the risk of osteoporotic fractures, such as hip fractures. Here, we examine whether two measures of endothelial dysfunction are related to hip fracture risk.

METHODS

Participants for this study were 2792 individuals (mean age 78.6 years) who had flow-mediated dilation (FMD) measured after ischemia in the forearm and 2255 adults (mean age 73.3 years) with measured soluble intercellular adhesion molecule (siCAM) levels, a constitutive endothelial cell membrane protein associated with the initiation of atherosclerosis. Mean follow-up was 9.7 and 11.7 years, respectively. There were 375 and 265 incident hip fractures, respectively, in each group.

RESULTS

In Cox proportional hazards models, there was no significant association between FMD response and incident hip fracture (HR per 1% higher FMD was 0.98 [0.93, 1.04]; p = 0.44). In exploratory analyses, when data were examined dichotomously, participants in the lowest 80% of FMD (≤ 4.5%) had an adjusted 1.29 (0.98, 1.68; p = 0.067) higher hazard of hip fracture compared to participants in the upper 20% of FMD change. There were no significant associations between siCAM and incident hip fracture whether examined as a continuous or dichotomized variable.

CONCLUSIONS

Among older adults, two measures of endothelial dysfunction were not significantly associated with hip fracture risk. There was a trend for higher fracture risk with lower FMD.

Correlation between serum Dickkopf-1 (DKK1) levels and coronary artery stenosis

BACKGROUND AND AIMS

To study the correlation between the level of serum Dickkopf-1 (DKK1) and the degree of coronary artery stenosis in patients with coronary atherosclerotic heart disease.

METHODS AND RESULTS

In 2018, general data and biochemical indexes of 311 patients who underwent coronary angiography were recorded. Before procedure, arterial blood was drawn and the concentrations of DKK1, retinol binding protein 4 (RBP4), plasminogen activator inhibitor (PAI-1) were measured. Based on coronary angiography results, subjects were divided into a coronary heart disease (CHD) group; and a non-coronary heart disease (non-CHD)group. The CHD group was divided into three subgroups: the low Gensini score; the middle Gensini score; and the high Gensini score subgroups. Compared with those of the non-CHD group, DKK1, RBP4 and PAI-1 of the CHD group were significantly higher, while the OC was lower. DKK1,RBP4 and PAI-1 levels of the middle and high Gensini subgroups were significantly higher, compared with that of the low Gensini subgroup. Differences between osteocalcin (OC), beta-isomerized C-terminal telopeptidase (β-CTX), and 25(OH)₂D₃ of the three subgroups were not significant. Correlation between DKK1 and the inflammatory factors, RBP4 and PAI-1, was positive. Correlation between DKK1 and β - CTX, 25(OH)₂D₃ and OC was not significant. DKK1 was a risk factor for CHD. The degree of coronary artery stenosis was related to DKK1 concentration.

CONCLUSIONS

Serum DKK1 levels in coronary heart disease patients were significantly higher, and positively correlated with the degree of coronary artery stenosis. DKK1 level is an independent risk factor for coronary heart disease.

Cardiac Mesenchymal Stem Cell-like Cells Derived from a Young Patient with Bicuspid Aortic Valve Disease Have a Prematurely Aged Phenotype

There is significant interest in the role of stem cells in cardiac regeneration, and yet little is known about how cardiac disease progression affects native cardiac stem cells in the human heart. In this brief report, cardiac mesenchymal stem cell-like cells (CMSCLC) from the right atria of a 21-year-old female patient with a bicuspid aortic valve and aortic stenosis (referred to as biscuspid aortic valve disease BAVD-CMSCLC), were compared with those of a 78-year-old female patient undergoing coronary artery bypass surgery (referred to as coronary artery disease CAD-CMSCLC). Cells were analyzed for expression of MSC markers, ability to form CFU-Fs, metabolic activity, cell cycle kinetics, expression of NANOG and p16, and telomere length. The cardiac-derived cells expressed MSC markers and were able to form CFU-Fs, with higher rate of formation in CAD-CMSCLCs. BAVD-CMSCLCs did not display normal MSC morphology, had a much lower cell doubling rate, and were less metabolically active than CAD-CMSCLCs. Cell cycle analysis revealed a population of BAVD-CMSCLC in G2/M phase, whereas the bulk of CAD-CMSCLC were in the G0/G1 phase. BAVD-CMSCLC had lower expression of NANOG and shorter telomere lengths, but higher expression of p16 compared with the CAD-CMSCLC. In conclusion, BAVD-CMSCLC have a prematurely aged phenotype compared with CAD-CMSCLC, despite originating from a younger patient.

Osteocalcin-expressing endothelial progenitor cells and serum osteocalcin forms are independent biomarkers of coronary atherosclerotic disease severity in male and female patients

PURPOSE

Osteocalcin (OC), an osteoblast-derived regulator of metabolic processes, and circulating early endothelial progenitor cells (EPC, CD34 - /CD133 + /KDR +) expressing OC (OC +) are potential candidates linking bone metabolism and the vasculature and might be involved in vascular atherosclerotic calcification. This study aimed at assessing the association of circulating levels of different OC forms and of EPCs count with disease severity in patients with documented coronary atherosclerosis (CAD).

METHODS

Patients (n = 59) undergoing coronary angiography were divided, according to stenosis severity, into (1) early coronary atherosclerosis (ECA) (n = 22), and (2) late coronary atherosclerosis (LCA) (n = 37). Total OC (TOC), carboxylated OC (cOC), undercarboxylated OC (unOC) were quantified by ELISA. EPC OC + count was assessed by flow cytometry.

RESULTS

EPC OC + counts showed significant differences between ECA and LCA groups. unOC and unOC/TOC ratio were inversely correlated with EPC OC + count. A significant decrease in TOC and unOC plasma levels was associated with higher cardiovascular risk factors (CVRFs) number. EPC OC + count was correlated with LDL-C, total cholesterol, and triglycerides, with a greater significance in the LCA group. No association between the different forms of circulating OC (TOC, ucOC, cOC) and severity of CAD was found.

CONCLUSION

This study showed a significant association between EPCs (CD34 - /CD133 + /KDR + /OC +), CAD severity and CVRFs, suggesting an active role for EPC OC + in the development of CAD. An inverse correlation between TOC, ucOC, and number of CVRFs was observed, suggesting that OC, regardless of its carboxylation status, may be developed as a further cardiovascular risk biomarker.

Space Flight-Promoted Insulin Resistance as a Possible Disruptor of Wound Healing

During space flight, especially when prolonged, exposure to microgravity results in a number of pathophysiological changes such as bone loss, muscle atrophy, cardiovascular and metabolic changes and impaired wound healing, among others. Interestingly, chronic low-grade inflammation and insulin resistance appear to be pivotal events linking many of them. Interestingly, real and experimental microgravity is also associated to altered wound repair, a process that is becoming increasingly important in view of prolonged space flights. The association of insulin resistance and wound healing impairment may be hypothesized from some dysmetabolic conditions, like the metabolic syndrome, type 2 diabetes mellitus and abdominal/visceral obesity, where derangement of glucose and lipid metabolism, greater low-grade inflammation, altered adipokine secretion and adipocyte dysfunction converge to produce systemic effects that also negatively involve wound healing. Indeed, wound healing impairment after traumatic events and surgery in space remains a relevant concern for space agencies. Further studies are required to clarify the molecular connection between insulin resistance and wound healing during space flight, addressing the ability of physical, endocrine/metabolic, and pharmacological countermeasures, as well as nutritional strategies to prevent long-term detrimental effects on tissue repair linked to insulin resistance. Based on these considerations, this paper discusses the pathophysiological links between microgravity-associated insulin resistance and impaired wound healing.

Osteogenic Circulating Endothelial Progenitor Cells are Associated with Vascular Aging of the Large Arteries in Rheumatoid Arthritis

Background and Aim

Rheumatoid arthritis is associated with both abnormal bone metabolism and accelerated vascular aging but a mechanistic link was lacking. This study aims to investigate the role of osteocalcin (OCN)-expressing circulating endothelial progenitor cells (EPCs) in vascular aging, as determined by arterial calcifications in rheumatoid arthritis.

Methods

We performed flow cytometry studies in 145 consecutive patients with rheumatoid arthritis to determine osteogenic circulating levels of OCN-positive (OCN+) CD34+KDR+ and OCN+CD34+ versus conventional early EPC CD34+CD133+KDR+. Total calcium load of the thoracic aorta (ascending plus descending) and the carotid arteries were assessed by non-contrast computed tomography (CT) and contrast CT angiography.

Results

Osteogenic EPCs OCN+CD34+KDR+ (P = 0.002) and OCN+CD34+ (P = 0.001), together with clinical parameters of age, history of hypertension, systolic blood pressure, serum levels of triglycerides, HbA1c and creatinine, use of leflunomide and brachial-ankle pulse-wave velocity (all P < 0.05), were associated with the clustered presence of aortic and carotid calcification. Multivariable analyses revealed that circulating OCN+CD34+KDR+ (B = 14.4 [95% CI 4.0 to 24.8], P = 0.007) and OCN+CD34+ (B = 9.6 [95% CI 4.9 to 14.3], P < 0.001) remained independently associated with increased aortic calcium load. OCN+CD34+ EPC (B = 0.8 [95% CI 0.1 to 1.5], P = 0.023), but not OCN+CD34+KDR+ EPC (B = 1.2 [95% CI −0.2 to 2.6], P = 0.09), was further independently associated with carotid calcium load. In comparison, conventional early EPC CD34+CD133+KDR+ had no significant association with aortic or carotid calcium load (P = 0.46 and 0.88, respectively).

Conclusion

Circulating level of osteogenic EPC is associated with increased vascular aging in terms of calcification of the large arteries in patients with rheumatoid arthritis. The findings may suggest a role of the bone-vascular axis underlying vascular aging in rheumatic diseases. Further research is needed to characterize the mechanistic links and basis of these observations.

IMPROvE-CED Trial: Intracoronary Autologous CD34+ Cell Therapy for Treatment of Coronary Endothelial Dysfunction in Patients With Angina and Non-Obstructive Coronary Arteries

Background: Coronary endothelial dysfunction (CED) causes angina/ischemia in patients with no-obstructive CAD (NOCAD). Patients with CED have decreased number and function of CD34+ cells involved in normal vascular repair with microcirculatory regenerative potential and paracrine anti-inflammatory effects. We evaluated safety and potential efficacy of intracoronary (IC) autologous CD34+ cell therapy for CED.

Methods: Twenty NOCAD patients with invasively-diagnosed CED and persistent angina despite maximally-tolerated medical therapy (MTMT) underwent baseline exercise stress test (EST), GCSF-mediated CD34+ cell-mobilization, leukapheresis, and selective 1x105 CD34+ cells/kg infusion into LAD. Invasive CED evaluation and EST were repeated 6-months after cell infusion. Primary endpoints were safety and effect of IC autologous CD34+ cell therapy on CED at 6-months follow-up. Secondary endpoints were change in CCS angina class, as-needed sublingual nitroglycerin use/day, Seattle Angina Questionnaire (SAQ) scores, and exercise time at 6-months. Change in CED was compared to that of 51 historic-control NOCAD patients treated with MTMT alone.

Results: Mean age was 52{plus minus}13 years, 75% women. No death, myocardial infarction, or stroke occurred. IC CD34+ cell infusion improved microvascular CED [% acetylcholine-mediated coronary blood flow increased from 7.2 (-18.0-32.4) to 57.6 (16.3-98.3) %, p=0.014], decreased CCS angina class (3.7{plus minus}0.5 to 1.7{plus minus}0.9, Wilcoxon signed-rank test p=0.00018) and sublingual nitroglycerin use/day [1 (0.4-3.5) to 0 (0-1), Wilcoxon signed-rank test p=0.00047], and improved all SAQ scores with no significant change in exercise time at 6-months follow-up. Historic-control patients had no significant change in CED.

Conclusion: A single IC autologous CD34+ cell infusion was safe and may potentially be an effective disease-modifying therapy for microvascular CED in humans. Clinical Trial Registration: NCT03471611

Contributions of the Endothelium to Vascular Calcification

Vascular calcification (VC) increases morbidity and mortality and constitutes a significant obstacle during percutaneous interventions and surgeries. On a cellular and molecular level, VC is a highly regulated process that involves abnormal cell transitions and osteogenic differentiation, re-purposing of signaling pathways normally used in bone, and even formation of osteoclast-like cells. Endothelial cells have been shown to contribute to VC through a variety of means. This includes direct contributions of osteoprogenitor cells generated through endothelial-mesenchymal transitions in activated endothelium, with subsequent migration into the vessel wall. The endothelium also secretes pro-osteogenic growth factors, such as bone morphogenetic proteins, inflammatory mediators and cytokines in conditions like hyperlipidemia, diabetes, and renal failure. High phosphate levels caused by renal disease have deleterious effects on the endothelium, and induction of tissue non-specific alkaline phosphatase adds to the calcific process. Furthermore, endothelial activation promotes proteolytic destruction of the internal elastic lamina that serves, among other things, as a stabilizer of the endothelium. Appropriate bone mineralization is highly dependent on active angiogenesis, but it is unclear whether the same relationship exists in VC. Through its location facing the vascular lumen, the endothelium is the first to encounter circulating factor and bone marrow-derived cells that might contribute to osteoclast-like versus osteoblast-like cells in the vascular wall. In the same way, the endothelium may be the easiest target to reach with treatments aimed at limiting calcification. This review provides a brief summary of the contributions of the endothelium to VC as we currently know them.

Serum alkaline phosphatase levels are associated with coronary artery calcification patterns and plaque vulnerability

OBJECTIVES

This study aimed to investigate the association of serum alkaline phosphatase (ALP) with calcification patterns and plaque morphology detected by intravascular ultrasound (IVUS) in acute coronary syndrome (ACS) patients.

BACKGROUND

ALP has been shown to predict vascular calcification and long-term cardiovascular events. However, the relationship between ALP and vascular calcification patterns or plaque morphology remains unclear.

METHODS

In total, 328 ACS patients who underwent IVUS examinations were screened from January 2017 to December 2018; among them, 234 eligible participants were grouped according to the tertiles of ALP levels (<68, 68-80, and >80 IU/L). Demographic data and IVUS parameters were documented and analyzed.

RESULTS

After adjusting for potential confounders, independent associations were observed between ALP and the presence of coronary calcification, spotty calcification, minimum lumen area (MLA) ≤ 4.0 mm² , and plaque burden (PB) > 70%. Compared with the lowest ALP tertile group, the highest ALP group had higher risks of calcification (odds ratio [OR], 2.85; 95% confidence interval [95%CI], 1.38-5.90; p = .005), spotty calcification (OR, 1.86; 95%CI, 1.09-3.84; p = .012), MLA≤4.0 mm² (OR, 3.32; 95%CI, 1.51-7.28; p = .003), and PB > 70% (OR, 4.59; 95%CI, 1.83-11.50; p = .001). Similar results were found when ALP was analyzed as a continuous variable or a category variate according to the cut-off value determined by the receiver operating characteristic curve analysis. Furthermore, the model including clinical factors and ALP significantly improved the predictive power for coronary calcification, spotty calcification, MLA≤4.0 mm² , and PB > 70%.

CONCLUSION

Our findings suggest that ALP may be a potential predictive biomarker for calcification and plaque vulnerability.

Role of Inflammation in Coronary Epicardial and Microvascular Dysfunction

There is accumulating evidence highlighting a close relationship between inflammation and coronary microvascular dysfunction (CMD) in various experimental and clinical settings, with major clinical implications. Chronic low-grade vascular inflammation plays important roles in the underlying mechanisms behind CMD, especially in patients with coronary artery disease, obesity, heart failure with preserved ejection fraction and chronic inflammatory rheumatoid diseases. The central mechanisms of coronary vasomotion abnormalities comprise enhanced coronary vasoconstrictor reactivity, reduced endothelium-dependent and -independent coronary vasodilator capacity and increased coronary microvascular resistance, where inflammatory mediators and responses are substantially involved. How to modulate CMD to improve clinical outcomes of patients with the disorder and whether CMD management by targeting inflammatory responses can benefit patients remain challenging questions in need of further research. This review provides a concise overview of the current knowledge of the involvement of inflammation in the pathophysiology and molecular mechanisms of CMD from bench to bedside.

Compositional change of gut microbiome and osteocalcin expressing endothelial progenitor cells in patients with coronary artery disease

Osteogenic endothelial progenitor cells (EPCs) contribute to impaired endothelial repair and promote coronary artery disease (CAD) and vascular calcification. Immature EPCs expressing osteocalcin (OCN) has been linked to unstable CAD; however, phenotypic regulation of OCN-expressing EPCs is not understood. We hypothesized that gut-microbiome derived pro-inflammatory substance, trimethylamine N-oxide (TMAO) might be associated with mobilization of OCN-expressing EPCs. This study aimed to investigate the association between dysbiosis, TMAO, and circulating mature and immature OCN-expressing EPCs levels in patients with and without CAD. We included 202 patients (CAD N = 88; no CAD N = 114) who underwent assessment of EPCs using flow cytometry and gut microbiome composition. Mature and immature EPCs co-staining for OCN were identified using cell surface markers as CD34+/CD133-/kinase insert domain receptor (KDR)+ and CD34-/CD133+/KDR+ cells, respectively. The number of observed operational taxonomy units (OTU), index of microbial richness, was used to identify patients with dysbiosis. The number of immature OCN-expressing EPCs were higher in patients with CAD or dysbiosis than patients without. TMAO levels were not associated with circulating levels of OCN-expressing EPCs. The relative abundance of Ruminococcus gnavus was moderately correlated with circulating levels of immature OCN-expressing EPCs, especially in diabetic patients. Gut dysbiosis was associated with increased levels of TMAO, immature OCN-expressing EPCs, and CAD. The relative abundance of Ruminococcus gnavus was correlated with immature OCN-expressing EPCs, suggesting that the harmful effects of immature OCN-expressing EPCs on CAD and potentially vascular calcification might be mediated by gut microbiome-derived systemic inflammation.

Promise of autologous CD34+ stem/progenitor cell therapy for treatment of cardiovascular disease

CD34+ cells are haematopoietic stem cells used therapeutically in patients undergoing radiation or chemotherapy due to their regenerative potential and ability to restore the haematopoietic system. In animal models, CD34+ cells have been associated with therapeutic angiogenesis in response to ischaemia. Several trials have shown the potential safety and efficacy of CD34+ cell delivery in various cardiovascular diseases. Moreover, Phase III trials have now begun to explore the potential role of CD34+ cells in treatment of both myocardial and peripheral ischaemia. CD34+ cells have been shown to be safe and well-tolerated in the acute myocardial infarction (AMI), heart failure, and angina models. Several studies have suggested potential benefit of CD34+ cell therapy in patients with coronary microvascular disease as well. In this review, we will discuss the therapeutic potential of CD34+ cells, and describe the pertinent trials that have used autologous CD34+ cells in no-options refractory angina, AMI, and heart failure. Lastly, we will review the potential utility of autologous CD34+ cells in coronary endothelial and microvascular dysfunction.

Cumulative Rheumatic Inflammation Modulates the Bone-Vascular Axis and Risk of Coronary Calcification

Background

Rheumatic diseases are related to both abnormal bone turnover and atherogenesis, but a mechanistic link was missing.

Methods and Results

We investigated the effect of cumulative rheumatic inflammation (CRI) on risk of coronary calcification in a retrospective cohort of 145 rheumatoid arthritis patients. A time‐adjusted aggregate CRI score was derived by conglomerating all quarterly biomarker encounters of serum C‐reactive protein over 60 months immediately preceding computed tomography coronary angiography. Flow cytometry was performed to measure the osteocalcin‐positive (OCN⁺) CD34⁺KDR⁺ and OCN⁺CD34⁺ circulating endothelial progenitor cells (EPCs). Conventional early circulating EPCs CD34⁺CD133⁺KDR⁺ was determined. Coronary calcification was defined as any Agatston score >0. 50% of patients (n=72/145) had coronary calcification. CRI score was associated with presence of coronary calcification (P=0.004) (multivariable‐adjusted: highest versus lowest quartile: odds ratio=5.6 [95% CI 1.1–28.9], P=0.041). Receiver operating characteristics curve revealed divergent behavior of OCN‐expressing circulating EPCs (OCN⁺CD34⁺EPCs: area under the curve=0.60, P=0.034; OCN⁺CD34⁺KDR⁺EPCs: area under the curve=0.59, P=0.053, positive predictors) versus conventional early EPCs (CD34⁺CD133⁺KDR⁺: area under the curve=0.60, P=0.034, negative predictor) for coronary calcification, which persisted after multivariable adjustments (OCN⁺CD34⁺KDR⁺ [>75th percentile]: odds ratio=7.2 [95% CI 1.8–27.9], P=0.005; OCN⁺CD34⁺EPCs [>75th percentile]: odds ratio=6.0 [95% CI 1.5–23.3], P=0.010; CD34⁺CD133⁺KDR⁺ [>75th percentile: odds ratio=0.3 [95% CI 0.1–1.0], P=0.053). Intriguingly, the CRI score was associated with increased OCN⁺CD34⁺EPCs (highest versus lowest quartile: B=+25.6 [95% CI 0.8–50.5] [×10³/mL peripheral blood], P=0.043), but reduced CD34⁺CD133⁺KDR⁺EPCs (highest versus lowest quartile: B=−16.2 [95% CI −31.5 to −0.9], P=0.038).

Conclusions

Preceding 60 months of CRI is associated with increased risk of coronary calcification and altered OCN expression in circulating EPCs.

The biology of vascular calcification

Vascular calcification (VC), characterized by different mineral deposits (i.e., carbonate apatite, whitlockite and hydroxyapatite) accumulating in blood vessels and valves, represents a relevant pathological process for the aging population and a life-threatening complication in acquired and in genetic diseases. Similarly to bone remodeling, VC is an actively regulated process in which many cells and molecules play a pivotal role. This review aims at: (i) describing the role of resident and circulating cells, of the extracellular environment and of positive and negative factors in driving the mineralization process; (ii) detailing the types of VC (i.e., intimal, medial and cardiac valve calcification); (iii) analyzing rare genetic diseases underlining the importance of altered pyrophosphate-dependent regulatory mechanisms; (iv) providing therapeutic options and perspectives.

Exosomes secreted from osteocalcin-overexpressing endothelial progenitor cells promote endothelial cell angiogenesis

Exosome secretion is an important paracrine way of endothelial progenitor cells (EPCs) to modulate resident endothelial cells. The osteocalcin (OCN)-expressing EPCs have been found to be increased in cardiovascular disease patients and are considered to be involved in the process of coronary atherosclerosis. Since OCN has been proven to prevent endothelial dysfunction, this study aimed to evaluate the effect of exosomes derived from OCN-overexpressed EPCs on endothelial cells. Exosomes derived from EPCs (Exos) and OCN-overexpressed EPCs (OCN-Exos) were isolated and incubated with rat aorta endothelial cells (RAOECs) with or without the inhibition of OCN receptor G protein-coupled receptor family C group 6 member A (GPRC6A). The effects of exosomes on the proliferation activity of endothelial cells were evaluated by CCK-8 assay, and the migration of endothelial cells was detected by wound healing assay. A tube formation assay was used to test the influence of exosomes on the angiogenesis performance of endothelial cells. Here, we presented that OCN was packed into Exos and was able to be transferred to the RAOECs via exosome incorporation, which was increased in OCN-Exos groups. Compared with Exos, OCN-Exos had better efficiency in promoting RAOEC proliferation and migration and tube formation. The promoting effects were impeded after the inhibition of GPRC6A expression in RAOECs. These data suggest that exosomes from OCN-overexpressed EPCs have a beneficial regulating effect on endothelial cells, which involved enhanced OCN-GPRC6A signaling.

Osteogenic circulating endothelial progenitor cells are linked to electrocardiographic conduction abnormalities in rheumatic patients

BACKGROUND

Osteogenic circulating endothelial progenitor cells (EPC) play a pathogenic role in cardiovascular system degeneration through promulgating vasculature calcification, but its role in conduction disorders as part of the cardiovascular degenerative continuum remained unknown.

AIM

To investigate the role of osteocalcin (OCN)-expressing circulating EPCs in cardiac conduction disorders in the unique clinical sample of rheumatoid arthritis (RA) susceptible to both abnormal bone metabolism and cardiac conduction disorders.

METHODS

We performed flow cytometry studies in 134 consecutive asymptomatic patients with rheumatoid arthritis to derive osteogenic circulating OCN-positive (OCN+) CD34+KDR+ vs. CD34+CD133+KDR+ conventional EPC. Study endpoint was the prespecified combined endpoint of electrocardiographic conduction abnormalities.

RESULTS

Total prevalence of cardiac conduction abnormality was 9% (n = 12). All patients except one had normal sinus rhythm. One patient had atrial fibrillation. No patient had advanced atrioventricular (AV) block. Prevalence of first-degree heart block (>200 ms), widened QRS duration (>120 ms) and right bundle branch block were 6.7%, 2.1%, and 2.2% respectively. Circulating osteogenic OCN⁺ CD34⁺ KDR⁺ EPCs were significantly higher among patients with cardiac conduction abnormalities (p = 0.039). Elevated OCN⁺ CD34⁺ KDR⁺ EPCs> 75th percentile was associated with higher prevalence of cardiac conduction abnormalities (58.3% vs. 20.02%, p = 0.003). Adjusted for potential confounders, elevated OCN⁺ CD34⁺ KDR⁺ EPCs> 75th percentile remained independently associated with increased risk of cardiac conduction abnormalities (OR = 4.4 [95%CI 1.2-16.4], p = 0.028). No significant relation was found between conventional EPCs CD34+CD133+KDR+ and conduction abnormalities (p = 0.36).

CONCLUSIONS

Elevated osteogenic OCN⁺ CD34⁺ KDR⁺ EPCs are independently associated with the presence of electrocardiographic conduction abnormalities in patients with rheumatoid arthritis, unveiling a potential novel pathophysiological mechanism.

Circulating Osteogenic Progenitor Cells in Mild, Moderate, and Severe Aortic Valve Stenosis

The aim of this study was to characterize endothelial progenitor cells with osteoblastic phenotype (EPC-OCNs) and their role in individuals with varying degrees of aortic stenosis (AS). Peripheral blood mononuclear cells retrieved from blood samples of individuals with mild (n=40), moderate (n=35), or severe (n=103) AS from September 16, 2008, through March 30, 2015, were analyzed by flow cytometry for the EPC surface markers CD34, CD133, and kinase insert domain receptor (KDR) and the osteoblastic cell surface marker OCN. Levels of EPC-OCNs were correlated with AS severity and calcifications. Patients with severe AS had significantly elevated numbers of total circulating EPC-OCNs, including the EPC-OCN subtypes CD133⁺/OCN⁺, CD34⁺/CD133⁺/OCN⁺, and CD133⁺/KDR⁺/OCN⁺, compared with those with mild AS. Individuals with moderate AS also had significantly increased numbers of the circulating progenitor cell CD133⁺/OCN⁺ compared with patients with mild AS. There was a significant association between total circulating EPC-OCN levels and aortic valve (AV) calcification, AV mean gradient, and AV area measured by echocardiography. In summary, this study found the presence of circulating EPC-OCNs in patients with progressive AV stenosis. These findings might support the potential role for EPC-OCNs in the progression of AV stenosis and calcification.

The Emerging Role of Bone Markers in Diagnosis and Risk Stratification of Patients With Coronary Artery Disease

Molecules that govern bone metabolism, such as osteoprotegerin (OPG) and osteopontin (OPN), have been isolated from other tissues, including blood vessels. Atherosclerosis and coronary artery disease (CAD) are leading causes of mortality worldwide. Despite novel biochemical and imaging techniques, early detection of CAD is still unsatisfactory. Experimental data indicate that bone turnover markers (BTMs) contribute to the development of atherosclerosis. This finding has sparked interest in their clinical use. This narrative review analyzed information from >50 human studies, which strongly suggest that OPG, OPN, and alkaline phosphatase (ALP) serum concentrations are altered in patients with CAD. Osteoprotegerin seems to be more useful for the detection of early disease, while OPN and ALP are recruited in vessels after the establishment of disease. Osteocalcin may be used as a flow cytometry marker for endothelial progenitor cells and can constitute a marker to monitor response to interventional treatments and risk of restenosis. However, most data derive from observational studies. Incorporation of BTMs in multifactorial computational algorithms could further determine their role in CAD diagnosis and prognosis together with other imaging techniques and biochemical markers.

Local Production of Soluble Urokinase Plasminogen Activator Receptor and Plasminogen Activator Inhibitor-1 in the Coronary Circulation Is Associated With Coronary Endothelial Dysfunction in Humans

Background Soluble urokinase plasminogen activator receptor (su PAR ) is a proinflammatory biomarker associated with immune activation and fibrinolysis inhibition. Plasminogen activator inhibitor ( PAI -1) is associated with excessive fibrin accumulation, thrombus formation, and atherosclerosis. The relationship between cross-coronary su PAR and PAI -1 production and endothelial dysfunction remains unknown. Methods and Results Seventy-nine patients (age 53±10 years, 75% women) with angina and normal coronary arteries or mild coronary artery disease (<40% stenosis) on angiogram underwent acetylcholine assessment of epicardial endothelial dysfunction (mid-left anterior descending coronary artery diameter decrease >20% after acetylcholine) and mircovascular endothelial dysfunction (coronary blood flow change <50% after acetylcholine). Simultaneous left main and coronary sinus su PAR and PAI -1 levels were measured in each patient before acetylcholine administration, and cross-coronary su PAR and PAI -1 production rates were calculated. Patients' characteristics, except for age (51±10 versus 57±9, P=0.02), and resting coronary hemodynamics were not significantly different between patients with (26%) versus without (74%) epicardial endothelial dysfunction. Patients' characteristics and resting coronary hemodynamics were not significantly different between those with (62%) and those without (38%) mircovascular endothelial dysfunction. Patients with mircovascular endothelial dysfunction demonstrated local coronary su PAR production versus su PAR extraction in patients with normal microvascular function (median 25.8 [interquartile range 121.6, -23.7] versus -12.7 [52.0, -74.8] ng/min, P=0.03). Patients with epicardial endothelial dysfunction had higher median coronary PAI -1 production rates compared with those with normal epicardial endothelial function (1224.7 [12 940.7, -1915.4] versus -187.4 [4444.7, -4535.8] ng/min, P=0.03). Conclusions su PAR is released in coronary circulation of patients with mircovascular endothelial dysfunction and extracted in those with normal microvascular function. Cross-coronary PAI -1 release is higher in humans with epicardial endothelial dysfunction.

Differential ability of formononetin to stimulate proliferation of endothelial cells and breast cancer cells via a feedback loop involving MicroRNA-375, RASD1, and ERα

For postmenopausal cardiovascular disease, long-term estrogen therapy may increase the risk of breast cancer. To reduce this risk, estrogen may be replaced with the phytoestrogen formononetin, but how formononetin acts on vascular endothelial cells (ECs) and breast cancer cells is unclear. Here, we show that low concentrations of formononetin induced proliferation and inhibited apoptosis more strongly in cultured human umbilical vein endothelial cells (HUVECs) than in breast cancer cells expressing estrogen receptor α (ERα) (MCF-7, BT474) or not (MDA-MB-231), and that this differential stimulation was associated with miR-375 up-regulation in HUVECs. For the first time, we demonstrate the presence of a feedback loop involving miR-375, ras dexamethasone-induced 1 (RASD1), and ERα in normal HUVECs, and we show that formononetin stimulated this feedback loop in HUVECs but not in MCF-7 or BT474 cells. In all three cell lines, formononetin increased Akt phosphorylation and Bcl-2 expression. Inhibiting miR-375 blocked these changes and increased proliferation in HUVECs, but not in MCF-7 or BT474 cells. In ovariectomized rats, formononetin increased uterine weight and caused similar changes in levels of miR-375, RASD1, ERα, and Bcl-2 in aortic ECs as in cultured HUVECs. In mice bearing MCF-7 xenografts, tumor growth was stimulated by 17β-estradiol but not by formononetin. These results suggest selective action of formononetin in ECs (proliferation stimulation and apoptosis inhibition) relative to breast cancer cells, possibly via a feedback loop involving miR-375, RASD1, and ERα. This differential effect may explain why formononetin may not increase the risk of postmenopausal breast cancer.

Mitoprotection attenuates myocardial vascular impairment in porcine metabolic syndrome

Metabolic syndrome (MetS) leads to cardiac vascular injury, which may reflect in increased retention of endothelial progenitor cells (EPCs). Coronary endothelial cell (EC) mitochondria partly regulate vascular function and structure. We hypothesized that chronic mitoprotection would preserve EC mitochondria and attenuate coronary vascular injury and dysfunction in swine MetS. Pigs were studied after 16 wk of diet-induced MetS, MetS treated for the last 4 wk with the mitochondria-targeted peptide elamipretide (ELAM; 0.1 mg/kg sc once daily), and lean controls ( n = 6 each). Cardiac remodeling and function were assessed in vivo by multidetector-computed tomography (CT), and coronary artery and sinus blood samples were collected. EC mitochondrial density, apoptosis, oxidative stress, endothelial nitric oxide synthase immunoreactivity, myocardial microvascular density (three-dimensional microcomputed tomography), and coronary endothelial function (organ bath) were assessed ex vivo. The number and arteriovenous gradient of CD34⁺/KDR⁺ EPCs were calculated by FACS (a negative net gradient indicating EPC retention). MetS and MetS + ELAM pigs developed similar MetS (obesity, hyperlipidemia, insulin resistance, and hypertension). EC mitochondrial density decreased in MetS animals compared with lean animals but normalized in MetS + ELAM animals. ELAM also attenuated EC oxidative stress and apoptosis and improved subendocardial microvascular density. ELAM-induced vasculoprotection was reflected by decreased coronary retention of EPCs. ELAM also partly improved endothelial nitric oxide synthase immunoreactivity, coronary endothelial function, and vessel maturity, whereas myocardial perfusion was unaffected. Chronic mitoprotection improved coronary EC mitochondrial density and decreased vascular remodeling and dysfunction. However, additional mitochondria-independent mechanisms likely contribute to MetS-induced cardiac vascular injury. NEW & NOTEWORTHY The present study shows that chronic mitoprotection preserved coronary endothelial cell mitochondria and decreased vascular injury, subendocardial microvascular loss, coronary retention of endothelial progenitor cells, and release of markers of vascular injury. However, myocardial perfusion remained blunted, suggesting that additional mitochondria-independent mechanisms likely contribute to metabolic syndrome-induced cardiac vascular injury.

Endothelial and cardiac progenitor cells for cardiovascular repair: A controversial paradigm in cell therapy

Stem cells have the potential to differentiate into cardiovascular cell lineages and to stimulate tissue regeneration in a paracrine/autocrine manner; thus, they have been extensively studied as candidate cell sources for cardiovascular regeneration. Several preclinical and clinical studies addressing the therapeutic potential of endothelial progenitor cells (EPCs) and cardiac progenitor cells (CPCs) in cardiovascular diseases have been performed. For instance, autologous EPC transplantation and EPC mobilization through pharmacological agents contributed to vascular repair and neovascularization in different animal models of limb ischemia and myocardial infarction. Also, CPC administration and in situ stimulation of resident CPCs have been shown to improve myocardial survival and function in experimental models of ischemic heart disease. However, clinical studies using EPC- and CPC-based therapeutic approaches have produced mixed results. In this regard, intracoronary, intra-myocardial or intramuscular injection of either bone marrow-derived or peripheral blood progenitor cells has improved pathological features of tissue ischemia in humans, despite modest or no clinical benefit has been observed in most cases. Also, the intriguing scientific background surrounding the potential clinical applications of EPC capture stenting is still waiting for a confirmatory proof. Moreover, clinical findings on the efficacy of CPC-based cell therapy in heart diseases are still very preliminary and based on small-size studies. Despite promising evidence, widespread clinical application of both EPCs and CPCs remains delayed due to several unresolved issues. The present review provides a summary of the different applications of EPCs and CPCs for cardiovascular cell therapy and underlies their advantages and limitations.

Is chronic kidney disease-mineral and bone disorder associated with the presence of endothelial progenitor cells with a calcifying phenotype?

Background: Chronic kidney disease-mineral and bone disorder (CKD-MBD) has been implicated in vascular calcification pathogenesis. CKD-MBD results in alterations in the number and function of circulating endothelial progenitor cells (EPCs), physiological regulators of angiogenesis and vessel repair, commonly defined as proangiogenic progenitor cells (PACs) by the antigen pattern CD34+CD133+KDR+CD45– and putative EPCs by the pattern CD34+CD133−KDR+CD45–. These cells might acquire a calcifying phenotype in CKD-MBD, expressing mineralization biomarkers. We investigated the expression of vitamin D receptor (VDR) and osteocalcin (OC) on EPCs of healthy individuals and haemodialysis patients, and their possible associations with circulating biomarkers of inflammation and vascular calcification.

Methods: We compared EPC counts, expressing VDR or OC, in 23 healthy subjects versus 53 haemodialysis patients, 17 of them without vitamin D receptor agonist (VDRA) therapy and 35 treated with calcitriol (n  =  17) or paricalcitol (n  =  18). The correlations with serum levels of inflammatory and calcification indexes were also analysed.

Results: All subsets expressing VDR or OC were significantly higher in haemodialysis patients compared with healthy controls, but PACs were increased only in VDRA treatment subgroup, while putative EPCs showed a similar rise also in untreated patients. In VDRA-untreated patients, OC+  PACs correlated positively with calcium levels, while in VDRA-treated patients, VDR+ PACs correlated positively with interleukin 6 levels, and OC+  PACs correlated positively 25-hydroxyvitamin D levels.

Conclusions: Our data suggest that in CKD-MBD, EPCs undergo an endothelial-to-procalcific shift, representing a risk factor for vascular calcification. A link between mineral disorders and vitamin D replacement therapy emerged, with potential adverse effects for CKD patients.

Serum levels of undercarboxylated osteocalcin are related to cardiovascular risk factors in patients with type 2 diabetes mellitus and healthy subjects

AIM

To determine a potential relationship between serum undercarboxylated (ucOC) concentration and cardiovascular risk factors in type 2 diabetes (T2D) patients and healthy subjects (HS).

METHODS

A cross-sectional study was conducted on 140 subjects classified into two groups, 70 with T2D and 70 HS. Medical history and physical examination with anthropometric measurements were obtained from all subjects. Body fat percentage was determined by bioelectrical impendency analysis. Serum ucOC concentration was determined by enzyme immunoassay, while serum levels of insulin and hsCRP were obtained using high sensitivity enzyme-linked immunosorbent assay. Insulin resistance was determined using the homeostasis model assessment-IR. Lipid profile [triglycerides, total cholesterol (TC), high-density lipoproteins (HDL-c), low density lipoproteins (LDL-c), very low-density lipoproteins] was determined by spectrophotometry and standard formulas when applicable.

RESULTS

The T2D patient group showed significantly higher values of waist circumference, waist-to-hip ratio, systolic blood pressure (SBP), diastolic blood pressure (DBP), current smoking, and alcohol use when compared to the HS group (P < 0.05). We observed a significantly lower serum ucOC concentration in T2D than in HS (1.5 ± 1.4 vs 2.3 ± 1.8, P < 0.05). In the whole study population, ucOC concentration was inversely correlated with body mass index (BMI) (r = -0.236, P < 0.05), fasting plasma glucose (r = -0.283, P < 0.01) and HDL-c (r = -0.255, P < 0.05); and positively correlated with LDL-c/HDL-c ratio (r = 0.306, P < 0.05) and TC/HDL-c ratio (r = 0.284, P < 0.05). In the T2D group, serum ucOC concentration was inversely correlated with BMI (r = -0.310, P < 0.05) and body-fat percentage (r = -0.311, P < 0.05), and positively correlated with DBP (r = 0.450, P < 0.01). In HS group a positive correlation between serum levels of ucOC and SBP (r = 0.277, P < 0.05) was observed.

CONCLUSION

Serum ucOC is a potential marker for cardiovascular risk in Mexicans because it is related to adiposity parameters, blood pressure and lipid profile.

Uric Acid Is Associated With Inflammation, Coronary Microvascular Dysfunction, and Adverse Outcomes in Postmenopausal Women

Uric acid is a risk factor for coronary artery disease in postmenopausal women, but the association with inflammation and coronary endothelial dysfunction (CED) is not well defined. The aim of this study was to determine the relationship of serum uric acid (SUA), inflammatory markers, and CED. In this prospective cohort study, SUA, high-sensitivity C-reactive protein levels, and neutrophil count were measured in 229 postmenopausal women who underwent diagnostic catheterization, were found to have no obstructive coronary artery disease, and underwent coronary microvascular function testing, to measure coronary blood flow response to intracoronary acetylcholine. The average age was 58 years (interquartile range, 52-66 years). Hypertension was present in 48%, type 2 diabetes mellitus in 5.6%, and hyperlipidemia in 61.8%. CED was diagnosed in 59% of postmenopausal women. Mean uric acid level was 4.7±1.3 mg/dL. Postmenopausal women with CED had significantly higher SUA compared with patients without CED (4.9±1.3 versus 4.4±1.3 mg/dL; P=0.02). There was a significant correlation between SUA and percent change in coronary blood flow to acetylcholine (P=0.009), and this correlation persisted in multivariable analysis. SUA levels were significantly associated with increased neutrophil count (P=0.02) and high-sensitivity C-reactive protein levels (P=0.006) among patients with CED, but not among those without CED. SUA is associated with CED in postmenopausal women and may be related to inflammation. These findings link SUA levels to early coronary atherosclerosis in postmenopausal women.

Circulating osteogenic endothelial progenitor cell counts: new biomarker for the severity of coronary artery disease

BACKGROUND

There is increasing evidence implying that the early and functionally highly active circulating endothelial progenitor cell (CEPC) phenotype (CD34-/CD133+/KDR+) with osteogenic potential (OCN+) might link between vascular atherosclerotic calcification and mechanisms of bone metabolism. We sought to evaluate the early OCN+ CEPC counts as an independent biomarker for the severity of coronary artery disease (CAD).

METHODS

Peripheral blood samples were drawn from 593 patients undergoing clinically indicated coronary angiography. CAD severity was assessed by the presence of significant coronary artery stenosis (CAS) as well as an ordinal categorical variable. Subjects were followed for all-cause death over a median follow-up of 40months.

RESULTS

OCN+ early CEPC counts (square-root transformed) were independently associated with the presence of significant CAS [odds ratio (OR) per standard deviation (SD) increment: 1.389, 95% confidence interval [CI]: 1.131 to 1.707, p=0.002). Similar association was observed with an increase in levels of CAS (OR: 1.353, 95% CI: 1.157 to 1.582, p<0.001). There was a weak tendency between OCN+ early CEPC counts and all-cause mortality (p=0.090), whereas the highest decile of OCN+ early CEPC counts had a 2.991-fold increased risk of all-cause death (p=0.047).

CONCLUSIONS

We demonstrate for the first time an independent, significant, and strong correlation between OCN+ early CEPC counts and CAD severity. Additionally, very high numbers of OCN+ early CEPC tend to be linked to the risk of all-cause mortality.

Cardiovascular Safety in Drug Development

As drug development becomes a long and demanding process, it might also become a barrier to medical progress. Drug safety concerns are responsible for many of the resources consumed in launching a new drug. Despite the money and time expended on it, a significant number of drugs are withdrawn years or decades after being in the market. Cardiovascular toxicity is one of the major reasons for those late withdrawals, meaning that many patients are exposed to unexpected serious cardiovascular risks. It seems that current methods to assess cardiovascular safety are imperfect, so new approaches to avoid the exposure to those undesirable effects are quite necessary. Endothelial dysfunction is the earliest detectable pathophysiological abnormality, which leads to the development of atherosclerosis, and it is also an independent predictor for major cardiovascular events. Endothelial toxicity might be the culprit of the cardiovascular adverse effects observed with a significant number of drugs. In this article, we suggest the regular inclusion of the best validated and less invasive endothelial function tests in the clinical phases of drug development in order to facilitate the development of drugs with safer cardiovascular profiles.

Challenges and opportunities for stem cell therapy in patients with chronic kidney disease

Chronic kidney disease (CKD) is a global health care burden affecting billions of individuals worldwide. The kidney has limited regenerative capacity from chronic insults, and for the most common causes of CKD, no effective treatment exists to prevent progression to end-stage kidney failure. Therefore, novel interventions, such as regenerative cell-based therapies, need to be developed for CKD. Given the risk of allosensitization, autologous transplantation of cells to boost regenerative potential is preferred. Therefore, verification of cell function and vitality in CKD patients is imperative. Two cell types have been most commonly applied in regenerative medicine. Endothelial progenitor cells contribute to neovasculogenesis primarily through paracrine angiogenic activity and partly by differentiation into mature endothelial cells in situ. Mesenchymal stem cells also exert paracrine effects, including proangiogenic, anti-inflammatory, and antifibrotic activity. However, in CKD, multiple factors may contribute to reduced cell function, including older age, coexisting cardiovascular disease, diabetes, chronic inflammatory states, and uremia, which may limit the effectiveness of an autologous cell-based therapy approach. This Review highlights current knowledge on stem and progenitor cell function and vitality, aspects of the uremic milieu that may serve as a barrier to therapy, and novel methods to improve stem cell function for potential transplantation.

Calcifying circulating cells: an uncharted area in the setting of vascular calcification in CKD patients

Vascular calcification, occurring during late-stage vascular and valvular disease, is highly associated with chronic kidney disease-mineral and bone disorders (CKD-MBD), representing a major risk factor for cardiovascular morbidity and mortality. The hallmark of vascular calcification, which involves both media and intima, is represented by the activation of cells committed to an osteogenic programme. Several studies have analysed the role of circulating calcifying cells (CCCs) in vascular calcification. CCCs are bone marrow (BM)-derived cells with an osteogenic phenotype, participating in intima calcification processes and defined by osteocalcin and bone alkaline phosphatase expression. The identification of CCCs in diabetes and atherosclerosis is the most recent, intriguing and yet uncharted chapter in the scenario of the bone-vascular axis. Whether osteogenic shift occurs in the BM, the bloodstream or both, is not known, and also the factors promoting CCC formation have not been identified. However, it is possible to recognize a common pathogenic commitment of inflammation in atherosclerosis and diabetes, in which metabolic control may also have a role. Currently available studies in patients without CKD did not find an association of CCCs with markers of bone metabolism. Preliminary data on CKD patients indicate an implication of mineral bone disease in vascular calcification, as a consequence of functional and anatomic integrity interruption of BM niches. Given the pivotal role that parathyroid hormone and osteoblasts play in regulating expansion, mobilization and homing of haematopoietic stem/progenitors cells, CKD-MBD could promote CCC formation.

Coronary artery calcification is associated with high serum concentration of undercarboxylated osteocalcin in asymptomatic Korean men

CONTEXT

Osteocalcin is associated with energy metabolism and atherosclerosis, besides bone metabolism. However, the association between osteocalcin or its undercarboxylated form (ucOC) and coronary artery calcification is controversial.

OBJECTIVE

To evaluate the relationship between coronary artery calcium score (CACS) and the concentration of serum osteocalcin and ucOC.

DESIGN

Cross-sectional.

PATIENTS

A total of 162 subjects (114 men and 48 women) with no angina symptom.

MEASUREMENTS

Serum analyses included glucose, insulin and lipid profiles as well as osteocalcin and ucOC. Bone mineral density (BMD) was measured by dual X-ray absorptiometry. CACS was measured using multidetector computed tomography and categorized into CACS = 0 and CACS > 0.

RESULTS

The mean osteocalcin concentration in men was 15·6 ± 4·2 for CACS = 0 group and 14·1 ± 4·0 for CACS > 0 group, respectively (P = 0·050). In women, the osteocalcin concentration, ucOC concentration and ucOC to osteocalcin ratio (OCR) were not different between the CACS groups. However, the concentrations of osteocalcin and ucOC were significantly lower in women with hypertension or diabetes than those without, respectively. In the multivariate logistic regression models adjusted for medical history, body mass index, lipid profiles, insulin resistance and BMD in men, the higher concentration of ucOC and higher OCR showed significant association with coronary calcification (CACS > 0).

CONCLUSION

Higher ucOC concentration was associated with coronary artery calcification independent of conventional cardiovascular risk factors and BMD in men.

Effect of grape and other berries on cardiovascular health

Cardiovascular disease is a leading cause of death globally. Many cardiovascular risk factors can be modified through lifestyle modification, including dietary patterns that emphasize daily consumption of a variety of fruits and vegetables. Recent observational and clinical studies suggest that flavonoids, especially those abundant in grapes and other berries, may be associated with health benefits, particularly cardiovascular benefits. Human clinical data support cardioprotective benefits of grapes through inhibition of platelet aggregation, decreased low-density lipoprotein (LDL) oxidation, reduction in oxidative stress and improvements in endothelial function. Emerging evidence suggests that grapes may also have a favorable effect on blood lipids, decrease inflammation and reduce blood pressure in certain populations. Studies to date have shown that berries can have a beneficial effect on reducing LDL oxidation. Limited data suggest that berries may have a favorable effect on endothelial health and blood pressure. This review summarizes the current literature on human clinical studies examining the cardioprotective benefits of grapes and berries. Collectively, these data support the recommendation to incorporate products made with grapes and other berries into a heart-healthy diet.

Osteogenic monocytes within the coronary circulation and their association with plaque vulnerability in patients with early atherosclerosis

OBJECTIVES

This study tests the hypothesis that circulating mononuclear cells expressing osteocalcin (OCN) and bone alkaline phosphatase (BAP) are associated with distinct plaque tissue components in patients with early coronary atherosclerosis.

BACKGROUND

Plaque characteristics implying vulnerability develop at the earliest stage of coronary atherosclerosis. Increasing evidence indicates that cells from the myeloid lineage might serve as important mediators of destabilization. Plaque burden and its components were assessed regarding their relationship to monocytes carrying both pro-inflammatory (CD14) and osteogenic surface markers OCN and BAP.

METHODS

Twenty-three patients with angiographically non-obstructive coronary artery disease underwent coronary endothelial function assessment and virtual histology-intravascular ultrasound of the left coronary artery. Plaque composition was characterized in the total segment (TS) and in the target lesion (TL) containing the highest amount of plaque burden. Blood samples were collected simultaneously from the aorta and the coronary sinus. Circulating cell counts were then identified from each sample and a gradient across the coronary circulation was determined.

RESULTS

Circulating CD14+/BAP+/OCN+ monocytes correlate with the extent of necrotic core and calcification (r=0.53, p=0.010; r=0.55, p=0.006, respectively). Importantly, coronary retention of CD14+/OCN+ cells also correlates with the amount of necrotic core and calcification (r=0.61, p=0.003; r=0.61, p=0.003) respectively.

CONCLUSIONS

Our study links CD14+/BAP+/OCN+ monocytes to the pathologic remodeling of the coronary circulation and therefore associates these cells with plaque destabilization in patients with early coronary atherosclerosis.

Coronary microvascular endothelial dysfunction is an independent predictor of development of osteoporosis in postmenopausal women

BACKGROUND

A growing body of evidence links coronary artery atherosclerosis and calcification to osteoporosis in women. The endothelium plays a critical role in maintaining vascular integrity and may play a role in bone metabolism. We aimed to determine whether early coronary atherosclerosis, as detected by coronary microvascular endothelial dysfunction (CMED), predicts the development of osteoporosis in postmenopausal women.

METHODS

Coronary vascular reactivity was evaluated in 194 postmenopausal women greater than 50 years of age and with non-obstructive coronary arteries by administration of intracoronary acetylcholine during diagnostic angiography. CMED was defined as ≤50% increase in coronary blood flow from baseline in response to maximal dose. After a median follow-up of 7.0±0.3 years, patients were assessed by a questionnaire for development of osteoporosis.

RESULTS

The average age of the cohort was 60.9±7.4 years. Women with CMED were twice as likely to develop osteoporosis compared with women without endothelial dysfunction after adjustment for potential confounders (relative risk, 2.4; 95% confidence interval [CI], 1.1, 5.6, P=0.02). Epicardial endothelial dysfunction was not associated with development of osteoporosis.

DISCUSSION

Early coronary atherosclerosis with endothelial dysfunction is an independent marker for increased risk of developing osteoporosis in postmenopausal women greater than 50 years of age without obstructive coronary artery disease. The current study supports a link between coronary atherosclerosis and osteoporosis.

Vascular extracellular matrix in atherosclerosis

The extracellular matrix (ECM) is an essential component of the human body that is responsible for the proper function of various organs. Changes in the ECM have been implicated in the pathogenesis of several cardiovascular conditions including atherosclerosis, restenosis, and heart failure. Matrix components, such as collagens and noncollagenous proteins, influence the function and activity of vascular cells, particularly vascular smooth muscle cells and macrophages. Matrix proteins have been shown to be implicated in the development of atherosclerotic complications, such as plaque rupture, aneurysm formation, and calcification. ECM proteins control ECM remodeling through feedback signaling to matrix metalloproteinases (MMPs), which are the key players of ECM remodeling in both normal and pathological conditions. The production of MMPs is closely related to the development of an inflammatory response and is subjected to significant changes at different stages of atherosclerosis. Indeed, blood levels of circulating MMPs may be useful for the assessment of the inflammatory activity in atherosclerosis and the prediction of cardiovascular risk. The availability of a wide variety of low-molecular MMP inhibitors that can be conjugated with various labels provides a good perspective for specific targeting of MMPs and implementation of imaging techniques to visualize MMP activity in atherosclerotic plaques and, most interestingly, to monitor responses to antiatheroslerosis therapies. Finally, because of the crucial role of ECM in cardiovascular repair, the regenerative potential of ECM could be successfully used in constructing engineered scaffolds and vessels that mimic properties of the natural ECM and consist of the native ECM components or composite biomaterials. These scaffolds possess a great promise in vascular tissue engineering.

Isolation and characterization of human osteoblasts from needle biopsies without in vitro culture

SUMMARY

We isolate and characterize osteoblasts from humans without in vitro culture. These techniques should be broadly applicable to studying the pathogenesis of osteoporosis and other bone disorders.

INTRODUCTION

There is currently no data regarding the expression of specific genes or pathways in human osteoblasts that have not been subjected to extensive in vitro culture. Thus, we developed methods to rapidly isolate progressively enriched osteoblast populations from humans and characterized these cells.

METHODS

Needle bone biopsies of the posterior iliac crest were subjected to sequential collagenase digests. The cells from the second digest were stained with an alkaline phosphatase (AP) antibody, and the AP+ cells were isolated using magnetic cell sorting.

RESULTS

Relative to AP- cells, the AP+ cells contained virtually all of the mineralizing cells and were enriched for key osteoblast marker genes. The AP+ cells were further purified by depletion of cells expressing CD45, CD34, or CD31 (AP+/CD45/34/31- cells), which represented a highly enriched human osteoblast population devoid of hematopoietic/endothelial cells. These cells expressed osteoblast marker genes but very low to undetectable levels of SOST. We next used high-throughput RNA sequencing to compare the transcriptome of the AP+/CD45/34/31- cells to human fibroblasts and identified genes and pathways expressed only in human osteoblasts in vivo, but not in fibroblasts, including 448 genes unique to human osteoblasts.

CONCLUSIONS

We provide a detailed characterization of highly enriched human osteoblast populations without in vitro culture. These techniques should be broadly applicable to studying the pathogenesis of osteoporosis and other bone disorders.

A reappraisal of the role of circulating (progenitor) cells in the pathobiology of diabetic complications

Traditionally, the development of diabetic complications has been attributed to the biochemical pathways driving hyperglycaemic cell damage, while reparatory mechanisms have been long overlooked. A more comprehensive view of the balance between damage and repair suggests that an impaired regenerative capacity of bone marrow (BM)-derived cells strongly contributes to defective re-endothelisation and neoangiogenesis in diabetes. Although recent technological advances have redefined the biology and function of endothelial progenitor cells (EPCs), interest in BM-derived vasculotropic cells in the setting of diabetes and its complications remains high. Several circulating cell types of haematopoietic and non-haematopoietic origin are affected by diabetes and are potentially involved in the pathobiology of chronic complications. In addition to classical EPCs, these include circulating (pro-)angiogenic cells, polarised monocytes/macrophages (M1 and M2), myeloid calcifying cells and smooth muscle progenitor cells, having disparate roles in vascular biology. In parallel with the study of elusive progenitor cell phenotypes, it has been recognised that diabetes induces a profound remodelling of the BM stem cell niche. The alteration of circulating (progenitor) cells in the BM is now believed to be the link among distant end-organ complications. The field is rapidly evolving and interest is shifting from specific cell populations to the complex network of interactions that orchestrate trafficking of circulating vasculotropic cells.

Epicardial adipose tissue thickness as a predictor of impaired microvascular function in patients with non-obstructive coronary artery disease

OBJECTIVE

To determine if increased epicardial adipose tissue (EAT) measured by cardiac CT could be associated with impaired myocardial flow reserve (MFR) in patients with non-obstructive coronary artery disease (CAD).

BACKGROUND

Studies have shown that EAT volume is related to epicardial obstructive CAD, myocardial ischemia and major adverse cardiac events. However, the association between EAT with coronary microvascular dysfunction and impaired MFR has not been well clarified.

METHODS

Consecutive patients who underwent Rb-82 positron emission tomography (PET), coronary artery calcium (CAC) scoring and non-invasive coronary computed tomography angiography (CCTA) were screened. PET scans were analysed for standard myocardial perfusion (MPI) and MFR. CCTA results were analysed and only patients with non-obstructive CAD (<50% luminal diameter stenosis) were included. EAT thickness and volumes were measured from CT scans.

RESULTS

Of 137 patients without obstructive CAD by CCTA and with normal Rb-82 PET relative MPI, 26 (19.0%) patients had impaired MFR < 2 and 87 (64%) patients had CAC. EAT(thickness), EAT(volume) and CAC values were higher in patients with impaired MFR < 2 than those with normal MFR ≥ 2 (6.7 ± 1.6 mm vs 4.4 ± 1.0 mm, P < .0001; 119.0 ± 25.3 cm(3) vs 105.8 ± 30.5 cm(3), P < .04 and 508.9 ± 554.3 vs 167.8 ± 253.9, P < .0001, respectively). However, EAT(thickness) had a stronger negative correlation with MFR than EAT(volume) and CAC (r = -0.78 vs r = -0.25 and ρ = -0.32, P < .0001). With multivariable logistic regression analysis, only EAT(thickness) was independently associated with impaired MFR (OR 20.7, 95% CI 4.9-87.9, P < .0001). Importantly, the receiver-operator characteristic (ROC) curves demonstrated a superior performance of EAT(thickness) vs EAT(volume) and EAT(thickness) vs CAC in detecting impaired MFR (AUC: 0.945 vs 0.625, difference between AUC: 0.319, P < .0001; AUC: 0.945 vs 0.710, difference between AUC: 0.235, P < .0006, respectively). On ROC curve analysis, an EAT(thickness) cut-off value > 5.6 mm was optimal in detecting impaired MFR with a sensitivity and specificity of 81% and 92%, respectively.

CONCLUSIONS

Increased EAT appears to be associated with impaired MFR. This parameter may help improve detection of patients at risk of microvascular dysfunction.

The preventive effect of uncarboxylated osteocalcin against free fatty acid-induced endothelial apoptosis through the activation of phosphatidylinositol 3-kinase/Akt signaling pathway

OBJECTIVE

Increasing evidence suggests that osteocalcin (OC), one of the osteoblast-specific proteins, has been associated with atherosclerosis, but results are conflicting. The aim of this study was to elucidate the independent effect of uncarboxylated osteocalcin (ucOC), an active form of osteocalcin which has been suggested to have an insulin sensitizing effect, on vascular endothelial cells.

MATERIALS AND METHODS

We used human aortic endothelial cells and treated them with ucOC. Linoleic acid (LA) was used as a representative free fatty acid. Apoptosis was evaluated using various methods including a terminal deoxyribonucleotide transferase-mediated deoxyuridine triphosphate nick-end labeling analysis kit and Western blotting for cleaved caspase 3, cleaved poly (ADP-ribose) polymerase and Bcl-xL. The phosphorylations of Akt and endothelial nitric oxide synthase (eNOS) as well as the level of NO were measured to confirm the effect of ucOC on insulin signaling pathway.

RESULTS

Pretreatment of ucOC (30 ng/ml) prevented LA-induced apoptosis in insulin-stimulated endothelial cells; effects were abolished by pretreatment with the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor, wortmannin. Treatment of ucOC (ranged from 0.3 to 30 ng/ml) significantly increased the phosphorylation of Akt and eNOS and nitric oxide secretion from endothelial cells in a PI3-kinase dependent manner.

CONCLUSIONS

Our study is the first to demonstrate the independent effect of ucOC on vascular endothelial cells. Our results further suggest that ucOC could have beneficial effects on atherosclerosis.

Acceleration of bone repair in NOD/SCID mice by human monoosteophils, novel LL-37-activated monocytes

Background

An incomplete understanding of bone forming cells during wound healing and ectopic calcification has led to a search for circulating cells that may fulfill this function. Previously, we showed that monoosteophils, a novel lineage of calcifying/bone-forming cells generated by treatment of monocytes with the natural peptide LL-37, are candidates. In this study, we have analyzed their gene expression profile and bone repair function.

Methods and Findings

Human monoosteophils can be distinguished from monocytes, macrophages and osteoclasts by their unique up-regulation of integrin α3 and down-regulation of CD14 and CD16. Monoosteophils express high mRNA and protein levels of SPP1 (osteopontin), GPNMB (osteoactivin), CHI3L1 (cartilage glycoprotein-39), CHIT1 (Chitinase 1), MMP-7, CCL22 and MAPK13 (p38MAPKδ). Monocytes from wild type, but not MAPK13 KO mice are also capable of monoosteophil differentiation, suggesting that MAPK13 regulates this process. When human monoosteophils were implanted in a freshly drilled hole in mid-diaphyseal femurs of NOD/SCID mice, significant bone repair required only 14 days compared to at least 24 days in control treated injuries.

Conclusion

Human derived monoosteophils, characterized as CD45⁺α3⁺α3β⁺CD34⁻CD14⁻BAP (bone alkaline phosphatase)⁻ cells, can function in an animal model of bone injury.

Association between circulating osteoblast progenitor cells and aortic calcifications in women with postmenopausal osteoporosis

BACKGROUND AND AIMS

Ectopic artery calcification has been documented in women with postmenopausal osteoporosis, in whom an imbalance in the number of circulating osteoprogenitor cells (OPCs) has been identified. Circulating OPCs form calcified nodules in vitro; however, it remains unknown whether an association exists between the number of circulating OPCs and aortic calcifications. We investigated the relationship between OPCs and aortic calcifications in women with postmenopausal osteoporosis.

METHODS AND RESULTS

The number of circulating OPCs was quantified by FACS analysis in 50 osteoporotic postmenopausal women. OPCs were defined as CD15-/alkaline-phosphatase(AP)+ cells coexpressing or not CD34. Participants underwent measurement of markers of bone metabolism, bone mineral density and abdominal aortic calcium (AAC) by 64-slice computed tomography. Patients with AAC were older, had lower 25(OH)vitamin D levels and higher circulating CD15-/AP+/CD34- cells than those without AAC. Significant correlates of AAC included age (rho = 0.38 p = 0.006), calcium (rho = 0.35 p = 0.01), 25(OH)vitamin D (rho = -0.31, p = 0.03) and the number of CD15-/AP+/CD34- cells (rho = 0.55 p < 0.001). In regression analyses, the log-transformed number of CD15-/AP+/CD34- cells was associated with the presence (OR = 6.45, 95% CI 1.03-40.1, p = 0.04) and severity (β = 0.43, p < 0.001) of AAC, independent of age, 25(OH)vitamin D, calcium and other potential confounders. Patients with low 25(OH)vitamin D and high CD15-/AP+/CD34- cells had higher median AAC than other patients (1927/μL, 862-2714/μL vs 147/μL, 0-1665/μL, p = 0.003).

CONCLUSION

In women with postmenopausal osteoporosis, the number of circulating CD15-/AP+/CD34- cells is significantly associated with increased aortic calcifications, that appear to be correlated also with reduced 25(OH)vitamin D levels.

Increased tissue endothelial progenitor cells in end-stage lung diseases with pulmonary hypertension

BACKGROUND

Diffuse lung diseases promote the development of vascular changes and pulmonary hypertension (PH). Endothelial progenitor cells (EPCs) seem to be involved in pulmonary vascular remodeling. We evaluated circulating and intra-pulmonary EPCs in end-stage lung diseases in relation to pulmonary arterial pressure (PAP).

METHODS

The study included 19 patients affected by different end-stage lung diseases, with or without PH. Six lung donors were considered as control group. EPCs were measured in blood samples taken at the time of transplant from pulmonary arteries and veins (by flow cytometry) as well as in lung specimen sections (by confocal microscopy) and expressed as percentage of total number of cells.

RESULTS

The amount of EPC in lung specimens was significantly different according to type of disease (p = 0.001). Specifically, a higher number of EPCs was detected in idiopathic pulmonary hypertension and idiopathic pulmonary fibrosis with high (> 25 mm Hg) mean PAP (p = 0.03 for both) compared with chronic obstructive pulmonary disease and control group. There was a direct correlation between intrapulmonary EPCs and PAP. According to receiver operating characteristic curve analysis, the presence of > 3% EPCs had a 91% sensitivity and 93% specificity in identifying high mean PAP. There were no differences in circulating arterial or venous EPCs among groups.

CONCLUSIONS

Intra-pulmonary EPCs are increased in lung diseases with high PAP, suggesting that EPCs may contribute to vascular remodeling in end-stage pulmonary disease.

Atorvastatin-induced increase in progenitor cell levels is rather caused by enhanced receptor activator of NF-kappaB ligand (RANKL) cell proliferation than by bone marrow mobilization

BACKGROUND

Statins have been shown to increase the level of circulating progenitor cells in peripheral blood supposedly due to a mobilization of progenitor cells from the bone marrow niche. Osteoclast/osteoblast interaction has been associated with progenitor cell mobilization. Here, we investigated the role of statins on progenitor cell mobilization with a focus on bone metabolism.

METHODS AND RESULTS

FGF2(-/-) and wild type (wt) mice were treated with atorvastatin or placebo. In contrast to wt mice, the number of sca-1/flk-1 positive progenitor cells in peripheral blood (PB) of atorvastatin treated FGF2(-/-) mice did not increase, and was accompanied by a defective reendothelialization after perielectric injury of the common carotid artery. In wt, but not FGF2(-/-) mice, statin treatment was associated with increased levels of receptor activator of NF-κB ligand (RANKL) in bone marrow (BM) supernatant. Treatment with recombinant RANKL increased sca-1/flk-1 positive progenitors in FGF2(-/-) mice. Interestingly, osteoclast activation was not altered. To measure the egress of sca-1/flk-1 positive progenitor cells from the bone marrow, we performed in-situ perfusion experiments of isolated hind limbs. Mobilization was not significantly affected by atorvastatin in both wt and FGF2(-/-) mice. Furthermore, RANK - the specific receptor to RANKL - is expressed on progenitor cells, and RANKL stimulation increases cell proliferation in vitro and in vivo.

CONCLUSIONS

Atorvastatin treatment increases RANKL levels with no measurable effect on bone metabolism and mobilization of progenitor cells from BM to PB. RANKL is essential for the statin-mediated increase of progenitor cell levels but predominantly due to a RANKL-induced stimulation of cell proliferation.

Effects of bisphosphonate treatment on circulating osteogenic endothelial progenitor cells in postmenopausal women

OBJECTIVE

To evaluate whether bisphosphonates modulate vascular calcification by a modification in endothelial progenitor cells (EPCs) coexpressing osteoblastic surface markers and genes.

PATIENTS AND METHODS

We performed a double-blind, randomized study of 20 healthy, early postmenopausal women (from February 1, 2008, through July 31, 2008) treated with placebo or risedronate sodium (35 mg/wk) for 4 months. Peripheral blood was collected at baseline and 4 months to determine serum inflammatory markers, osteoprotegerin, and receptor activator of nuclear factor-κB ligand levels and bone turnover markers. Peripheral blood mononuclear cells were stained for EPC surface markers (CD34, CD133, and vascular endothelial growth factor receptor/kinase insert domain receptor) and osteoblast markers (osteocalcin, alkaline phosphatase, and Stro-1).

RESULTS

Risedronate treatment resulted in a significant down-regulation of gene sets for osteoblast differentiation and proliferation in EPCs with a trend of decreasing EPCs coexpressing osteocalcin.

CONCLUSION

Our findings indicate that bisphosphonate treatment down-regulates the expression of osteogenic genes in EPCs and suggest a possible mechanism by which bisphosphonates may inhibit vascular calcification.

Serum alkaline phosphatase is a predictor of mortality, myocardial infarction, or stent thrombosis after implantation of coronary drug-eluting stent

AIMS

The association between alkaline phosphatase (ALP) and mortality was reported in several subgroups of patients. But, the role of ALP in overall coronary artery disease (CAD) patients after percutaneous coronary intervention (PCI) remains unknown. The aim of this study was to examine the prognostic value of the ALP level in patients with CAD who underwent PCI with drug-eluting stent (DES).

METHODS AND RESULTS

We prospectively included CAD patients who underwent PCI with DES. After exclusion of patients with liver disease and cancer, 1636 patients were selected for the analysis of clinical outcomes (median duration of follow-up; 762 days, inter-quartile range; 494-1068 days), and were classified into tertiles by baseline measurements of ALP (<63, 63-78, and >78 IU/L). After adjustment of potential confounders including angiographic data, the independent and dose-dependent association was observed between tertile of ALP and the adjusted hazard ratio (HR) of all-cause mortality (P for trend < 0.0001). Specifically, compared with the lowest ALP tertile, the adjusted HR of all-cause mortality in the highest tertile was 4.21 (95% confidence interval 2.03-8.71). In subgroup of patients with stable or unstable angina, a similar association was noted (P for trend < 0.0001). In terms of cardiovascular mortality, myocardial infarction, and stent thrombosis, the adjusted HRs in the highest ALP tertile were 3.92 (1.37-11.20), 1.98 (0.91-4.29), and 2.73 (1.33-5.61), respectively, compared with the lowest tertile. Furthermore, evaluation of both ALP and C-reactive protein provided better predictive value than either alone. Interesting result suggesting the mechanism was that ALP was significantly associated with the presence of angiographic coronary calcification (P for trend = 0.046).

CONCLUSION

Our study demonstrated that the higher serum ALP level is an independent predictor of mortality, myocardial infarction, and stent thrombosis in CAD patients after PCI with DES.

Patients with an HbA1c in the prediabetic and diabetic range have higher numbers of circulating cells with osteogenic and endothelial progenitor cell markers

CONTEXT

Vascular calcification, an important feature of diabetic vasculopathy, is an active process potentially mediated by endothelial progenitor cells (EPCs) coexpressing the osteoblastic marker osteocalcin (OCN).

OBJECTIVE

In this study we tested the hypothesis that cells expressing these markers are associated with the presence of elevated glycated hemoglobin (HbA1c).

DESIGN, SETTING, AND PATIENTS

This was a cross-sectional comparison. Patients (n = 133, aged 57.4 ± 15.7 yr) were divided into two groups according to the presence of an HbA1c in a (pre-)diabetic (>5.6) or normal range at the time of blood sampling.

METHODS

Using flow cytometry of peripheral blood mononuclear cells (MNCs), cells positive for OCN, the EPC markers (CD34/KDR and CD133(+)/CD34(-)/KDR(+)) and OCN(+) EPCs were counted.

RESULTS

Patients with elevated HbA1c compared with those with normal HbA1c had a significantly higher percentage of circulating OCN(+) MNCs [4.6 (interquartile range 2.68-7.81%) vs. 3.12 (0.99-7.81%), P = 0.035], higher numbers of OCN(+)/CD133(+)/CD34(-)/KDR(+) cells [20 (9-74) vs. 8 (0-19) counts per 100,000 gated events, P < 0.001] and a higher fraction of CD133(+)/CD34(-)/KDR(+) and CD34/KDR cells coexpressing OCN (23.7 ± 24.3 vs. 40.5 ± 34.6%, P = 0.002 and 37.1 ± 39.5 vs. 59.7 ± 37.7%, P = 0.002, respectively). The association between circulating OCN(+)/CD133(+)/CD34(-)/KDR(+) cells and an HbA1c in the (pre-) diabetic range remained strong, even after adjusting for differences in obesity and cardiovascular risk factors, disease, and medications in a multivariate model [odds ratio 1.72 (1.21-2.61), P =0.002].

CONCLUSION

This study demonstrated that patients with HbA1c in the (pre-)diabetic range have a significant increase in OCN(+) MNCs, and OCN(+)/CD133(+)/CD34(-)/KDR(+) cells, in particular. Whether these cells increase vascular calcification in (pre-)diabetes warrants further studies.

Role of circulating osteogenic progenitor cells in calcific aortic stenosis

OBJECTIVES

The purpose of this study was to determine the role of circulating endothelial progenitor cells with osteoblastic phenotype (EPC-OCN) in human aortic valve calcification (AVC).

BACKGROUND

Recent evidence suggests that rather than passive mineralization, AVC is an active atherosclerotic process with an osteoblastic component resembling coronary calcification. We have recently identified circulating EPCs with osteogenic properties carrying both endothelial progenitor (CD34, KDR) and osteoblastic (osteocalcin [OCN]) cell surface markers.

METHODS

Blood samples from controls (n = 22) and patients with mild to moderate calcific aortic stenosis (mi-moAS, n = 17), severe calcific AS (sAS, n = 26), and both sAS and severe coronary artery disease (sCAD) (n = 33) were collected during diagnostic coronary angiography. By using flow cytometry, peripheral blood mononuclear cells were analyzed for CD34, KDR, and OCN. Resected normal and calcified aortic valves were analyzed histologically.

RESULTS

Patients with mi-moAS and patients with sAS/sCAD had significantly less EPCs (CD34+/KDR+/OCN-) than controls. Patients with sAS showed significantly higher numbers of EPC-OCN (CD34+/KDR+/OCN+) than controls. In addition, the percentage of EPC costaining for OCN was higher in all disease groups compared with controls. A subgroup analysis of younger patients with bicuspid sAS showed a similar pattern of significantly lower EPCs but a high percentage of coexpression of OCN. Immunofluorescence showed colocalization of nuclear factor kappa-B and OCN in diseased and normal valves. CD34+/OCN+ cells were abundant in the endothelial and deeper cell layers of calcific aortic valve tissue but not in normal aortic valve tissue.

CONCLUSIONS

Circulating EPC-OCN may play a significant role in the pathogenesis and as markers of prognostication of calcific AS.