On the Memory of a Chronic Illness

Endothelial Progenitor Cells for Diagnosis and Prognosis in Cardiovascular Disease

Objective. To identify, evaluate, and synthesize evidence on the predictive power of circulating endothelial progenitor cells (EPCs) in cardiovascular disease, through a systematic review of quantitative studies. Data Sources. MEDLINE was searched using keywords related to "endothelial progenitor cells" and "endothelium" and, for the different categories, respectively, "smoking"; "blood pressure"; "diabetes mellitus" or "insulin resistance"; "dyslipidemia"; "aging" or "elderly"; "angina pectoris" or "myocardial infarction"; "stroke" or "cerebrovascular disease"; "homocysteine"; "C-reactive protein"; "vitamin D". Study Selection. Database hits were evaluated against explicit inclusion criteria. From 927 database hits, 43 quantitative studies were included. Data Syntheses. EPC count has been suggested for cardiovascular risk estimation in the clinical practice, since it is currently accepted that EPCs can work as proangiogenic support cells, maintaining their importance as regenerative/reparative potential, and also as prognostic markers. Conclusions. EPCs showed an important role in identifying cardiovascular risk conditions, and to suggest their evaluation as predictor of outcomes appears to be reasonable in different defined clinical settings. Due to their capability of proliferation, circulation, and the development of functional progeny, great interest has been directed to therapeutic use of progenitor cells in atherosclerotic diseases. This trial is registered with registration number: Prospero CRD42015023717.

Endothelial Progenitor Cell Levels Predict Future Physical Function: An Exploratory Analysis From the VA Enhanced Fitness Study

BACKGROUND

Levels of circulating progenitor cells (CPCs) are depleted with aging and chronic injury and are associated with level of physical functioning; however, little is known about the correlation of CPCs with longer-term measures of physical capabilities. We sought to determine the association of CPCs with future levels of physical function and with changes in physical function over time.

METHODS

CPCs were measured in 117 participants with impaired glucose tolerance in the Enhanced Fitness clinical trial based on the cell surface markers CD34 and CD133 and aldehyde dehydrogenase (ALDH) activity at baseline, 3 months, and 12 months. Physical function was assessed using usual and rapid gait speed, 6-minute walk distance, chair stand time, and SF-36 physical functioning score and reassessed at 3 and 12 months after clinical intervention.

RESULTS

Higher baseline levels of CD133(+), CD34(+), CD133(+)CD34(+), and ALDH(br) were each highly predictive of faster gait speed and longer distance walked in 6 minutes at both 3 and 12 months. These associations remained robust after adjustment for age, body mass index, baseline covariates, and inflammation and were independent of interventions to improve physical fitness. Further, higher CPC levels predicted greater improvements in usual and rapid gait speed over 1 year.

CONCLUSIONS

Baseline CPC levels are associated not only with baseline mobility but also with future physical function, including changes in gait speed. These findings suggest that CPC measurement may be useful as a marker of both current and future physiologic aging and functional decline.

Depletion of circulating progenitor cells precedes overt diabetes: a substudy from the VA enhanced fitness trial

BACKGROUND

One theory of aging and disease development is that chronic injury (pathology) results in activation of regenerative processes and initial repair, with overt disease arising only after exhaustion of reparative capability leads to inadequate repair. While depletion of circulating progenitor cells (CPCs) has been noted in diabetes, the degree to which CPC depletion predates and is associated with propensity to develop overt disease is unclear.

METHODS

The Enhanced Fitness trial enrolled overweight/obese (body mass index >25) sedentary patients with glucose intolerance but without overt diabetes. Baseline CPCs were measured in 129 patients based on the cell surface markers CD34, CD133, and aldehyde dehydrogenase (ALDH) activity. HgbA1C, fasting insulin and glucose levels, and HOMA calculations were ascertained.

RESULTS

Lower counts of early angiogenic CPCs identified as CD34(+), CD34(+)CD133(+), and ALDH-bright (ALDH(br)) cells were associated with impairments in glucose homeostasis as reflected by HgbA1C, but not fasting insulin, glucose, or HOMA-IR. These associations remained when corrected for age and cardiovascular risk factors.

CONCLUSIONS/INTERPRETATION

The numbers of CD34(+) and ALDH(br) CPCs were significantly lower in patients with impaired glucose tolerance. Depletion of reparative capacity as reflected by loss of CPCs may presage overt disease as exemplified in this pre-diabetes model.

Lower levels of circulating progenitor cells are associated with low physical function and performance in elderly men with impaired glucose tolerance: a pilot substudy from the VA Enhanced Fitness trial

BACKGROUND

Aging is marked by a decline in physical function. Although the biological underpinnings for this remain unclear, loss of regenerative capacity has been proposed as one cause of the loss of physical function that occurs over time. The quantity of circulating progenitor cells (CPCs) may be one reflection of regenerative capability. We sought to determine whether certain specific CPC subpopulations were associated with physical function.

METHODS

Baseline CPCs were measured in 129 randomized participants in the Enhanced Fitness clinical trial based on the cell surface markers CD34, CD133, CD146, and CD14 and aldehyde dehydrogenase (ALDH) activity. Physical function was assessed using usual and rapid gait speed, 6-minute walk distance, chair stand time, and balance time.

RESULTS

Low counts of early angiogenic CPCs identified as CD34(+), CD34(+)CD133(+), and ALDH-bright (ALDH(br)) cells were associated with low usual gait speed (p < .005, p < .001, and p < .007), rapid gait speed (p < .001, p < .003, and p < .001), and 6-minute walking distance (all comparisons p < .001), and longer time required to complete five chair stands (p < .006, p < .002, and p < .004). CPC counts of mature endothelial or monocytic markers were not associated with physical function.

CONCLUSIONS

The numbers of CD34(+) and ALDH(br) CPCs are significantly lower in patients with impaired physical function. Further studies are needed to determine the underlying causes for this association.

Heartache and heartbreak--the link between depression and cardiovascular disease

The close, bidirectional relationship between depression and cardiovascular disease is well established. Major depression is associated with an increased risk of coronary artery disease and acute cardiovascular sequelae, such as myocardial infarction, congestive heart failure, and isolated systolic hypertension. Morbidity and mortality in patients with cardiovascular disease and depression are significantly higher than in patients with cardiovascular disease who are not depressed. Various pathophysiological mechanisms might underlie the risk of cardiovascular disease in patients with depression: increased inflammation; increased susceptibility to blood clotting (owing to alterations in multiple steps of the clotting cascade, including platelet activation and aggregation); oxidative stress; subclinical hypothyroidism; hyperactivity of the sympatho-adrenomedullary system and the hypothalamic-pituitary-adrenal axis; reductions in numbers of circulating endothelial progenitor cells and associated arterial repair processes; decreased heart rate variability; and the presence of genetic factors. Early identification of patients with depression who are at risk of cardiovascular disease, as well as prevention and appropriate treatment of cardiovascular disease in these patients, is an important and attainable goal. However, adequately powered studies are required to determine the optimal treatment regimen for patients with both depression and cardiovascular disorders.

Journey in antithrombotic strategies for ST-elevation myocardial infarction

Our understanding and treatment of the ST-elevation myocardial infarction (STEMI) has led to a tremendous improvement in the care and preservation of life affecting millions yearly. As the medical community continues to discover novel strategies in therapeutics and innovations in prevention, it is imperative to understand the scientific journey the treatment of STEMI has traveled. Furthermore, the research pillars that led to our understanding of the current paradigm of STEMI will be highlighted in an effort to illuminate the foundation on which we now stand.

Urotensin II induces migration of endothelial progenitor cells via activation of the RhoA/Rho kinase pathway

Urotensin II (UII) is a vasoactive peptide with many potent effects in the cardiorenovascular system and may be involved in the pathogenesis of atherosclerosis. Cardiovascular risk factors are often accompanied by reduced numbers of endothelial progenitor cells (EPCs) and their impaired migratory capacity. However, the role of UII in the migration of EPCs has not been reported so far. The aim of this study was to investigate whether UII influences the chemotactic function of bone marrow-derived EPCs and the possible signaling mechanisms involved. As a ligand for the orphan G-protein coupled receptor 14 (GPR14, UT receptor), UII exerts vasoactive functions through activation of the RhoA/Rho kinase pathway. We therefore analyzed the expression of GPR14 mRNA and protein, the activation of RhoA kinase and the phosphorylation of myosin light chain (MLC) in EPCs, isolated from the rat bone marrow. EPCs of 1-4 passages expressed GPR14 mRNA and protein. Chemotaxis assays were performed using Transwell cell-culture chambers with UII (10(-10)-10(-6) M), showing that UII induced chemotaxis of EPCs in a concentration-dependent manner after 3-h treatment (all p < 0.05), with the highest value (about 3-fold increase) at 10(-8) M. UII caused rapid activation of RhoA and increased phosphorylation of MLC. Conversely, a Rho-kinase inhibitor Y-27632 prevented the UII-induced migration and the phosphorylation of MLC. In conclusion, GPR14/UT receptor is expressed in EPCs, and UII induces migration of EPCs via activation of the RhoA/Rho kinase pathway. These findings provide new insights into the actions of UII in atherosclerosis.

Jay and Jeanie Schottenstein prize in cardiovascular science: predicting cardiovascular illnesses for the 21(st) century, and the unpredictable

Changes in our society such as the increasing cost of retirement and age redistribution toward a larger elderly population will require humans to remain highly functional until an advanced age. As a consequence, chronic illnesses that are primarily responsible for reducing functionality and life expectancy will require improved prevention and therapeutic strategies. In a global way, cardiovascular disease and cancer represent the most challenging disorders to maintaining the functional integrity of our fellow humans. A new theory has been derived from recent progress in our understanding of atherosclerosis as a key mechanism for cardiovascular disease and of cancer. Instructively, this theory provides a bridge at the stem cell level, linking most chronic disorders.

Frailty and its potential relevance to cardiovascular care

Frailty is characterized by vulnerability to acute stressors and is a consequence of decline in overall function and physiologic reserves. An estimated 7% of the US population older than 65 years and 30% of octogenarians are frail. The domains to define frailty include mobility, strength, balance, motor processing, cognition, nutrition, endurance, and physical activity. Pathophysiologic pathways leading to frailty involve a multisystem cascade that includes neuroendocrine dysfunction with lower insulin-like growth factor and dehydroepiandrosterone sulfate and an altered inflammatory milieu with increased levels of C-reactive protein, interleukins, tumor necrosis factor alpha, and abnormal coagulation. Frailty predicts death and heralds the transition to disability in general populations. As the population with coronary artery disease shifts toward older patients, physicians must consider the role of frailty in their patients. This review will enable clinicians to recognize frailty and consider its relevance in their daily practice. We also elaborate on reasons to consider frailty in older adults with cardiovascular disease and focus on its early identification, on referral to specialists, and on care after serious cardiac events.

Review: Endothelial progenitor cells: markers of vascular reparative capacity

Assessment of the propensity for vascular events has been based on measurement of risk factors predisposing one to vascular injury. These assessments are based on the strong associations between risk factors such as hypertension, cholesterol levels, smoking, and diabetes which were first described almost a half century ago. The more recent discovery of the relationship between ongoing inflammation and clinical outcomes has led to a variety of blood-based assays which may impart additional knowledge about an individual's propensity for future cardiovascular events. Vascular health is now better represented as a balance between ongoing injury and resultant vascular repair, mediated at least in part by circulating endothelial progenitor cells. To date, one's risk for vascular events has focused exclusively on assessing propensity for vascular damage, either by assessing conventional risk factors which were initially identified over half a century ago, or more recently by assessing markers of inflammation and other circulating factors which area related to subsequent clinical events. Circulating endothelial progenitor cells play important roles in accelerating endothelialization at areas of vascular damage, and EPC enumeration is a viable strategy for assessing reparative capacity. To date, EPC numbers have been correlated with the numbers of cardiovascular risk factors, extent of coronary disease, and future cardiovascular events. Given that EPC enumeration and functional characterization represent the only assessment of the reparative side of the balance between damage and renovation, this technique may offer independent and different assessment of propensity to cardiovascular injury, greatly improving risk stratification of patients.

A novel hypothesis of atherosclerosis: EPCs-mediated repair-to-injury

Recent findings demonstrate the vital role of endothelial progenitor cells in the homeostasis of the vessel wall and the development of atherosclerosis. Endothelial progenitor cells (EPCs) play important roles in repair-to-injury of arteries. Many evidences have shown Cardiovascular risk factors closely correlated with EPCs numbers and function. Levels of circulating EPCs represented a better predictor of endothelial function than conventional risk factors. Depletion of bone marrow and Cardiovascular risk factors are the two prerequisits of atherosclerosis. All conditions of manifest atherosclerotic disease are accompanied by reduced EPC numbers and migratory capacity. Therefore, based on response-to-injury hypothesis and these findings, we build up EPCs-mediated repair-to-injury hypothesis, which may have important therapeutic implications in the prevention and therapy of atherosclerosis. The use of EPCs for vascular repair may be important therapy strategies with a maximized benefit for the patient in the future.

Endothelial progenitor cells: a promising therapeutic alternative for cardiovascular disease

The integrity and functional activity of the endothelial monolayer play a critical role in preventing atherosclerotic disease progression. Endothelial cell (EC) damage by atherosclerosis risk factors can result in EC apoptosis with loss of the integrity of the endothelium. Thus, approaches to repair the injured vessels with the goal of regenerating ECs have been tested in preclinical experimental models and in clinical studies. Indeed, endothelial progenitor cells (EPCs) originating from the bone marrow have been shown to incorporate into sites of neovascularization and home to sites of endothelial denudation. These cells may provide an endogenous repair mechanism to counteract ongoing risk factor-induced endothelial injury and to replace dysfunctional endothelium. Risk factors for coronary artery disease, such as age, smoking, hypertension, hyperlipidemia, and diabetes, however, reduce the number and functional activity of circulating EPCs, potentially restricting the therapeutic prospective of progenitor cells and limiting the regenerative capacity. Furthermore, the impairment of EPCs by risk factors may contribute to atherogenesis and atherosclerotic disease progression. The article reviews the role of EPCs in atherogenesis and in predicting cardiovascular outcomes, and highlights the potential challenges in developing therapeutic strategies aiming to interfere with the balance of injury and repair mechanisms.

Circulating endothelial progenitor cells predict coronary artery disease severity

BACKGROUND

Circulating endothelial progenitor cells (EPCs) may play an important role in the body's defense against atherosclerosis. Previous studies have shown an association between EPC numbers and the presence of traditional coronary artery disease (CAD) risk factors. The relationship between EPC numbers and the severity of atherosclerosis is, however, not known.

METHODS

EPC counts were measured by quantitative cell culture in 122 patients undergoing diagnostic cardiac catheterization. The association between patients' EPC count and the presence of multivessel CAD and traditional cardiac risk factors was assessed using logistic regression analysis.

RESULTS

The median age of the study population was 58 years; 37% had multivessel CAD, 29% had diabetes, and 14% had myocardial infarction this admission. EPC counts did not vary significantly with most established cardiac risk factors but were lower in diabetics versus nondiabetics and trended toward lower numbers in older patients. EPC count was the second strongest predictor of multivessel CAD, after patient age. Patients with multivessel disease had significantly lower EPC counts than those without (median, 3 vs 13; P < .0088). For every 10 colony forming unit increase in EPCs, a patient's likelihood for multivessel CAD declined by 20% (P < .001).

CONCLUSION

This study demonstrates an inverse relationship between circulating EPCs and CAD severity, independent of traditional risk factors. If confirmed in ongoing studies, this may represent an important new diagnostic and therapeutic target for coronary disease treatment.