Endothelial Progenitor Cells In Subjects Research Articles

Atorvastatin enhances endothelial cell function in posttransplant poor graft function

AbstractPoor graft function (PGF) is a serious complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Murine studies suggest that endothelial progenitor cells (EPCs) are preferential supporting cells for hematopoietic stem cells in the bone marrow (BM) microenvironment. Our previous work found that a reduced number of BM EPCs was an independent risk factor for the occurrence of PGF after allo-HSCT. However, little is known about the functional role of BM EPCs and how to improve impaired BM EPCs in PGF. In the current study, we evaluated the function of BM EPCs in subjects with PGF postallotransplant. Moreover, we investigated whether atorvastatin could enhance the number and function of BM EPCs derived from subjects with PGF in vitro. Dysfunctional BM EPCs, which were characterized by impaired proliferation, migration, angiogenesis, and higher levels of reactive oxygen species and apoptosis, were revealed in subjects with PGF. Activation of p38 and its downstream transcription factor cyclic adenosine monophosphate–responsive element-binding protein were detected in BM EPCs from subjects with PGF. Furthermore, the number and function of BM EPCs derived from subjects with PGF were enhanced by atorvastatin treatment in vitro through downregulation of the p38 MAPK pathway. In summary, dysfunctional BM EPCs were observed in subjects with PGF. Atorvastatin treatment in vitro quantitatively and functionally improved BM EPCs derived from subjects with PGF through downregulation of the p38 MAPK pathway. These data indicate that atorvastatin represents a promising therapeutic approach for repairing impaired BM EPCs in subjects with PGF postallotransplant.

Dysfunction of Bone Marrow Endothelial Progenitor Cells from Subjects with Poor Graft Function Following Allogeneic Hematopoietic Stem Cell Transplantation Can be Improved By Atorvastatin

BackgroundPoor graft function (PGF) is a serious complication post allo-HSCT. The definition is a hypo- or aplastic bone marrow with 2 or 3 of the following: (1) neutrophils ≤0.5×10E+9/L; (2) platelets ≤20×10E+9/L; and/or (3) hemoglobin concentration ≤70 g/L for at least 3 consecutive days after day +28 post-HSCT. The mechanisms of PGF remain poorly understood. Murine studies suggest that endothelial progenitor cells (EPCs) are preferential supporting cells for hematopoietic stem cells (HSCs) in the bone marrow (BM) microenvironment. In addition, our previous prospective, nested case-control study found that a reduced number of BM EPCs was an independent risk factor for the occurrence of PGF after allo-HSCT. However, little is known about the functional role of BM EPCs and how to improve impaired BM EPCs in PGF.Atorvastatin is widely used in the treatment of dyslipidemia and associated vascular abnormalities. Furthermore, atorvastatin has been reported to improve the mobilization and function of circulating EPCs in a number of diseases, such as heart disease, diabetes and others. Nevertheless, no previous studies have focused on the roles of atorvastatin on bone marrow-derived EPCs in subjects with poor graft function following allo-HSCT.AimsTo evaluate the function of BM EPCs in subjects with PGF. Moreover, to investigate the effect of atorvastatin on the number and function of cultivated BM EPCs derived from subjects with PGF and its underling molecular mechanisms.MethodsThree cohorts were included: subjects with PGF (N=23), subjects with good graft function (N=23), defined as persistent successful engraftment after allotransplant, and transplant donors as normal controls (N=23). Atorvastatin (0.5nM,50nM,500nM) was administrated to the 5 day cultivated BM EPCs from subjects with PGF until tested on day 7. The number and functions of CD34(+)/CD133(+)/KDR(+)EPCs were evaluated by flow cytometry, cell counting, DiI-Ac-LDL and FITC-lectin-UEA-1 double staining, migration, tube formation test and apoptosis. Reactive Oxygen Species (ROS) level was evaluated by flow cytometry. Cell proliferation was determined by cell counting kit-8 assay. Protein expression for ERK,JNK, p38, Akt was measured by flow cytometry and western blots. EPCs-CD34+ co-culture system and Colony-forming unit (CFU) assays were used to evaluate the supporting effect that atorvastatin exposure on hematopoietic progenitors in vitro.ResultsHuman BM EPCs was characterized by the spindle shape and expression of CD34, CD309 and CD133 at day 7 of cultivation. Dysfunctional BM EPCs, which were characterized by impaired proliferation, migration, angiogenesis, and higher levels of reactive oxygen species and apoptosis, were revealed in subjects with PGF. Activation of p38 and its downstream transcription factor cAMP-responsive element-binding protein (CREB) were detected in BM EPCs from subjects with PGF. Furthermore, the number and function of BM EPCs derived from subjects with PGF were enhanced by atorvastatin treatment in vitro through down-regulation of the p38 mitogen-activated protein kinase (MAPK) pathway. The colony-forming unit plating efficiency in CD34+ BM cells was also improved by atorvastatin when co-cultured with BM EPCs from subjects with PGF. Atorvastatin demonstrated similar improvement effects on the number and function of bone marrow EPCs as ROS inhibitor and p38 inhibitor from subjects with PGF.ConclusionIn summary, dysfunctional BM EPCs were observed in subjects with PGF. Atorvastatin treatment in vitro quantitatively and functionally improved BM EPCs derived from subjects with PGF through down-regulation of the p38 MAPK pathway. These data indicate that atorvastatin represents a promising therapeutic approach for repairing impaired BM EPCs in subjects with PGF post-allotransplant. DisclosuresNo relevant conflicts of interest to declare.

Dysregulation of VEGF-induced proangiogenic Ca2+ oscillations in primary myelofibrosis-derived endothelial colony-forming cells

Endothelial progenitor cells could be implicated in the aberrant neoangiogenesis that occurs in bone marrow and spleen in patients with primary myelofibrosis (PMF). However, antivascular endothelial growth factor (VEGF) monotherapy had only a modest and transient effect in these individuals. Recently it was found that VEGF-induced proangiogenic intracellular Ca(2+) oscillations could be impaired in endothelial progenitor cells of subjects with malignancies. Therefore, we employed Ca(2+) imaging, wavelet analysis, and functional assays to assess whether and how VEGF-induced Ca(2+) oscillations are altered in PMF-derived endothelial progenitor cells. We focused on endothelial colony-forming cells (ECFCs), which are the only endothelial progenitor cell subtype capable of forming neovessels both in vivo and in vitro. VEGF triggers repetitive Ca(2+) spikes in both normal ECFCs (N-ECFCs) and ECFCs obtained from PMF patients (PMF-ECFCs). However, the spiking response to VEGF is significantly weaker in PMF-ECFCs. VEGF-elicited Ca(2+) oscillations are patterned by the interaction between inositol-1,4,5-trisphosphate-dependent Ca(2+) mobilization and store-operated Ca(2+) entry. However, in most PMF-ECFCs, Ca(2+) oscillations are triggered by a store-independent Ca(2+) entry pathway. We found that diacylglycerol gates transient receptor potential canonical 1 channel to trigger VEGF-dependent Ca(2+) spikes by recruiting the phospholipase C/inositol-1,4,5-trisphosphate signaling pathway, reflected as a decrease in endoplasmic reticulum Ca(2+) content. Finally, we found that, apart from being less robust and dysregulated as compared with N-ECFCs, VEGF-induced Ca(2+) oscillations modestly stimulate PMF-ECFC growth and in vitro angiogenesis. These results may explain the modest effect of anti-VEGF therapies in PMF.

Exercise training improves in vivo endothelial repair capacity of early endothelial progenitor cells in subjects with metabolic syndrome

Endothelial dysfunction and injury are considered to contribute considerably to the development and progression of atherosclerosis. It has been suggested that intense exercise training can increase the number and angiogenic properties of early endothelial progenitor cells (EPCs). However, whether exercise training stimulates the capacity of early EPCs to promote repair of endothelial damage and potential underlying mechanisms remain to be determined. The present study was designed to evaluate the effects of moderate exercise training on in vivo endothelial repair capacity of early EPCs, and their nitric oxide and superoxide production as characterized by electron spin resonance spectroscopy analysis in subjects with metabolic syndrome. Twenty-four subjects with metabolic syndrome were randomized to an 8 weeks exercise training or a control group. Superoxide production and nitric oxide (NO) availability of early EPCs were characterized by using electron spin resonance (ESR) spectroscopy analysis. In vivo endothelial repair capacity of EPCs was examined by transplantation into nude mice with defined carotid endothelial injury. Endothelium-dependent, flow-mediated vasodilation was analysed using high-resolution ultrasound. Importantly, exercise training resulted in a substantially improved in vivo endothelial repair capacity of early EPCs (24.0 vs 12.7%; p < 0.05) and improved endothelium-dependent vasodilation. Nitric oxide production of EPCs was substantially increased after exercise training, but not in the control group. Moreover, exercise training reduced superoxide production of EPCs, which was not observed in the control group. The present study suggests for the first time that moderate exercise training increases nitric oxide production of early endothelial progenitor cells and reduces their superoxide production. Importantly, this is associated with a marked beneficial effect on the in vivo endothelial repair capacity of early EPCs in subjects with metabolic syndrome.

Transplantation of Endothelial Progenitor Cells Improves Pulmonary Endothelial Function and Gas Exchange in Rabbits with Endotoxin-Induced Acute Lung Injury

Circulating endothelial progenitor cells (EPCs) have been therapeutically applied to aid vascular repair and myocardial regeneration. The number of circulating EPCs also provides invaluable outcome prediction for fatal diseases such as acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). However, evidence for the therapeutic potential of EPCs in subjects with ALI/ADRS is limited. Circulating EPCs were obtained from rabbits using Ficoll centrifugation. One week after culturing EPCs in endothelial growth medium-2, ALI was induced in rabbits by intratracheal instillation of lipopolysaccharide (500 μg/kg). Autologous EPCs or saline were administered IV after induction of ALI and animals were killed 2 days later. Pulmonary artery endothelial function and gas exchange were determined. Degrees of lung injury were assessed by alveolocapillary permeability, lung hemoglobin content, and myeloperoxidase activity. In comparison with controls, Po(2) in arterial blood was significantly elevated and pulmonary artery endothelium-dependent relaxation response was restored in rabbits receiving EPC transplantation. Lung water, Evan's blue, and bronchoalveolar lavage protein contents were significantly reduced in the EPC transplanted group, indicating a better preservation of the alveolocapillary membrane. Transplantation of EPCs decreased the lung hemoglobin level. Furthermore, expressions of CD11b and myeloperoxidase activity were also suppressed after administration of EPCs. Transplantation of EPCs restored pulmonary endothelial function, preserved integrity of the alveolocapillary barrier and suppressed the lung inflammatory response, thereby improving pulmonary gas exchange in rabbits with intratracheal lipopolysaccharide-induced ALI. Transplantation of EPCs can be a novel cell-based, endothelium-targeted therapeutic strategy for prevention and treatment of ALI/ARDS.

Decreased number and impaired functionality of endothelial progenitor cells in subjects with metabolic syndrome: Implications for increased cardiovascular risk

ObjectiveMetabolic syndrome (MetS) is characterized by low-grade inflammation and confers an increased risk for cardiovascular disease. Endothelial progenitor cells (EPCs) are a measure of vascular health and are decreased in patients with various risk factors for cardiovascular disease (CVD). There is a paucity of data examining the EPC status especially in terms of their functionality in MetS subjects without diabetes or cardiovascular disease. We aimed to enumerate and functionally characterize EPCs in subjects with MetS in comparison to healthy controls. MethodsThe study was performed at the University of California Davis Medical Center. Healthy controls (n=31) and MetS (n=46) subjects were included in the study. EPCs were enumerated in fasting blood by KDR/CD34 dual positivity. Functionality was assessed by the colony forming units (CFU) assay, migration and tubule formation. ResultsSubjects with MetS had significantly decreased number of EPCs compared to control subjects. Furthermore, EPCs from MetS subjects depicted significantly impaired clonogenic capacity, i.e., decreased colony forming units, and impaired capacity to incorporate into tubular structures suggesting functional impairment of EPCs from MetS subjects. ConclusionsWe make the novel observation that MetS subjects without diabetes or CVD have decreased EPC number and impaired functionality as compared to control subjects. These findings could contribute to the increased CV risk in this population.

Increased levels of circulating endothelial progenitor cells in subjects with moderate to severe chronic periodontitis

Emerging evidence shows that periodontal disease is associated with endothelial dysfunction. The purpose of this study was to determine the association between chronic periodontitis (CP) and circulating endothelial progenitor cells (EPC). Eighty-six non-smoking subjects (36 males and 50 females, aged 35-80 years) were recruited, including 23 subjects with no or mild CP and 63 subjects with moderate to severe CP. The levels of circulating EPC were quantitatively determined by fluorescence-activated cell analysis, including CD34+/kinase insert domain-containing receptor (KDR)+ (more mature EPC) and CD133+/KDR+ (less mature EPC). Periodontal conditions, the intima-media thickness of carotid arteries and circulating biomarkers were examined. Subjects with moderate to severe CP exhibited an increased risk of high EPC count, compared with those with no or mild CP: CD34+/KDR+ EPC [odds ratio (OR)=9.5, 95% confidence interval (95% CI) 1.5-61.0, p=0.018; CD133+/KDR+ EPC, OR=4.6, 95% CI 1.1-19.5, p=0.039]. C-reactive protein was significantly associated with high CD34+/KDR+ EPC count and age was inversely related with high EPC count. Age, gender and CD34+/KDR+ EPC were independent variables of increased carotid intima-media thickness (p<0.05). This study shows for the first time that moderate to severe CP is associated with an increased level of circulating EPC.

Dialysis modality is independently associated with circulating endothelial progenitor cells in end-stage renal disease patients

Numbers of endothelial progenitor cells (EPC) have been shown to be decreased in subjects with end-stage renal disease (ESRD). It is not clear, however, whether dialysis modality affects circulating EPCs in ESRD subjects. We examined the number of circulating EPCs in 67 continuous ambulatory peritoneal dialysis (CAPD) patients and age- and gender-matched 142 haemodialysis (HD) patients, and 78 subjects without chronic kidney disease. Arterial stiffness was analysed as pulse-wave velocity (PWV) for these patients, and their mutual relationship with circulating EPCs was examined. EPCs were measured as CD34(+) CD133(+) CD45(low) VEGFR2(+) cells determined by flow cytometry. The EPC numbers exhibited a strong correlation (R(2) = 0.866) with endothelial-colony forming units on culture assay. The levels of EPCs in HD or CAPD subjects were significantly lower than those in control subjects. Among ESRD subjects, the levels of EPC were significantly higher in CAPD subjects than those in HD subjects. In ESRD subjects, PWV levels tended to be associated with EPCs (Rs = -0.131, P = 0.058). However, the significant relationship between dialysis modality and circulating EPCs was independent of the levels of PWV. The association of circulating EPCs with dialysis modality was significant even after adjusting for other potential confounders, including age, gender, blood pressure, history of cardiovascular diseases, presence of diabetes, blood haemoglobin level and treatments with angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker or statin. CAPD treatment could be a positive regulator of number of circulating EPCs in subjects with ESRD, with the relationship independent of the status of arteriosclerosis.

Endothelial progenitor cell levels in obese men with the metabolic syndrome and the effect of simvastatin monotherapy vs. simvastatin/ezetimibe combination therapy

Endothelial progenitor cells (EPCs) contribute to endothelial regeneration and thereby protect against cardiovascular disease (CVD). Patients with manifest CVD have reduced EPC levels, but it is not clear if this also occurs in subjects at high CVD risk without manifest atherosclerotic disease. Therefore, we aimed to first, measure circulating levels of EPCs in subjects without manifest CVD but at high cardiovascular risk due to obesity and presence of the metabolic syndrome. Second, we evaluated the effect on EPC levels of two lipid-lowering treatments. Circulating CD34+KDR+ EPC levels were reduced by nearly 40% in obese men with the metabolic syndrome compared to non-obese healthy controls (331 +/- 193 vs. 543 +/- 164 EPC/mL, P = 0.006). In a randomized double-blind cross-over study comparing intensive lipid-lowering treatment using 80 mg simvastatin mono-treatment with combination treatment of 10 mg simvastatin and 10 mg ezetimibe, we found a similar treatment effect on EPC levels. Secondary analyses of these data suggested that both treatment regimens had increased circulating EPCs to control levels (626 +/- 428 after combination treatment, P < 0.01; 524 +/- 372 EPC/mL after monotherapy, P < 0.05). Serum levels of EPC-mobilizing factor SCF-sR correlated with reduced EPC levels and normalized concurrently with treatment. EPC levels are reduced in apparently healthy men with abdominal obesity and the metabolic syndrome, even in the absence of manifest CVD. This is important as EPCs contribute to endothelial regeneration and thereby protect against CVD. SCF-sR may be a candidate serum marker of circulating EPC levels. Treatment with low-dose statin with ezetimibe combination therapy or high-dose statin monotherapy has similar effects on the reduced EPC levels.

Significance of Endothelial Progenitor Cells in Subjects With Diabetes

Diabetes complications represent a huge burden for patients and health services. The fight against each single complication has led to significant improvements in diabetes care, especially for microvascular complications, yet macroangiopathy remains a major source of morbidity and mortality. A common approach for the prevention and treatment of diabetes complications relies on the understanding of their complex pathophysiology. A unifying biochemical theory suggests that oxidative stress underlies subsequent cellular damage pathways, which leads to diabetes complications, but common supracellular mechanisms are still unclear. Endothelial progenitor cells (EPCs) are circulating immature cells that contribute to vascular homeostasis and compensatory angiogenesis. During the last decade, data have become available indicating that alterations in EPCs may have an important causative role in the development and progression of virtually all diabetes complications. In this review, we will focus on the mechanisms of EPC reduction and dysfunction associated with diabetes by discussing their role in each single complication and possible therapeutic interventions. Diabetes is associated with a unique constellation of disabling complications. While it was originally thought that a single patient tends to develop the cluster of micro- or macrovascular complications, recent prospective studies show that typical markers of microvascular dysfunction, such as microalbuminuria or retinal vascular abnormalities, are associated with an increased risk of macrovascular events (1,2). These and other data suggest that there must be a unifying pathogenetic model underlying diabetes complications. To date, the most credited and supported model proposes that oxidative stress originating from mitochondria activates all subcellular damage pathways (3). However, subsequent events diverge for each complication, and there is not a supracellular unifying hypothesis. The discovery that a subset of circulating immature cells contributes to vascular homeostasis has been a major achievement in many fields of basic science. In this review, we will focus the attention on …

Circulating endothelial progenitor cells in subjects with erectile dysfunction

Erectile dysfunction (ED) is often the first clinical sign of endothelial dysfunction and may precede overt cardiovascular diseases. Bone marrow-derived endothelial progenitor cells migrate into the peripheral circulation to promote endothelial repair. The number of circulating progenitor cells is reduced in patients with cardiovascular risk factor. The objective of our study was to determine the number of these cells in patients with ED both with and without cardiovascular risk factors. These subjects have lower number of circulating progenitor cells, confirming the existence of an endothelial dysfunction and supplying the evidence that ED may be the first symptom of an endothelial damage.