OBJECTIVE—To determine the role of Wnt antagonist Dickkopf (DKK) 1 in human endothelial colony-forming cells (ECFCs) in view of the emerging importance of Wnt pathways in vascular biology.
METHODS ...AND RESULTS—Endothelial progenitor cells have been proposed to be crucial in tumor neovascularization. Recombinant DKK1 has been tested in ECFC angiogenic properties in vitro. DKK1 enhanced ECFC proliferation and the capacity of ECFCs to form pseudotubes in Matrigel. These effects have been attributed to enhancement of vascular endothelial growth factor receptor 2, SDF-1, and CXCR4. DKK1 gene silencing has been realized on ECFCs and mesenchymal stem cells, and we found that DKK1 silencing in the 2 cell types decreased their angiogenic potential. We then examined the possible role of DKK1 in tumor neovasculogenesis and found that blood vessels of breast cancer tissues expressed DKK1 far more strongly in human breast tumors than in normal breast tissues. By studying 62 human breast tumors, we found a significant positive correlation between DKK1 expression and von Willebrand factor. In vivo, DKK1 strongly enhanced the vascularization of Matrigel plugs and increased tumor size in a xenograft model of human breast carcinoma in nude mice.
CONCLUSION—DKK1 enhances angiogenic properties of ECFCs in vitro and is required for ECFC and mesenchymal stem cell angiogenic phenotypes in vivo. DKK1 also increases tumoral angiogenesis. Thus, we demonstrated a major role of DKK1 in angiogenic processes.
Congenital heart disease can be complicated by pulmonary arterial hypertension (PAH), the reversibility of which is often difficult to predict. We recently reported a lung biopsy study showing ...impaired apoptotic regulation of endothelial cells in irreversible PAH. The objective of the present study was to identify noninvasive biomarkers of endothelial turnover that could be used to identify congenital heart disease patients at risk of irreversible PAH.
Circulating endothelial cells (CECs) isolated with CD146-coated beads and circulating CD34(+)CD133(+) progenitor cells (CPCs) were quantified in peripheral vein, pulmonary artery, and pulmonary vein blood samples from 26 patients with congenital heart disease (16 with reversible PAH median age 2 years and 10 with irreversible PAH median age 9 years) and 5 control patients. Surgical lung biopsy was performed in 19 cases. As expected, endothelial remodeling was observed in irreversible PAH but not in reversible PAH. CEC and CPC numbers were each similar in the 3 types of blood samples. CEC numbers were significantly higher in patients with irreversible PAH (median 57 CEC/mL) than in patients with reversible PAH and control subjects (median 3 CEC/mL in the 2 groups). In contrast, CPC numbers did not differ among patients with irreversible or reversible PAH and control subjects (median 84, 64, and 44 CPC/10(5) lymphocytes, respectively, in the 3 groups).
Irreversible PAH in congenital heart disease is associated with endothelial damage and with increased circulating endothelial cell counts. The present study suggests that CECs could be a valuable tool to define therapeutic strategies in congenital heart disease patients with PAH.
OBJECTIVE—We examined whether plasma levels of angiogenic factors are altered in plasma of patients with peripheral arterial disease (PAD) and whether these factors affect endothelial progenitor ...cell–induced angiogenesis.
METHODS AND RESULTS—Plasma was collected from 184 patients with PAD and 330 age-matched healthy controls. Vascular endothelial growth factor and placental growth factor concentrations did not differ between the groups, whereas we found a linear correlation between PAD disease and thrombospondin (TSP)-1 plasma level. TSP-1 was expressed in newly formed vessels in PAD patients having received local injections of bone marrow mononuclear cells. To analyze the functional role of TSP-1 during neoangiogenesis, we used a Matrigel-plug assay and showed that vascularization of implanted Matrigel-plugs was increased in TSP-1 mice. Moreover, injections of TSP-1 in C57Bl6/J mice after hindlimb ischemia induced a significant decrease of blood flow recovery. To investigate the effects of TSP-1 on human endothelial colony-forming cell (ECFC) angiogenic potential, recombinant human TSP-1 and a small interfering RNA were used. In vitro, TSP-1 N-terminal part significantly enhanced ECFC adhesion, whereas recombinant human TSP-1 had a negative effect on ECFC angiogenic potential. This effect, mediated by CD47 binding, modulated stromal cell–derived factor 1/CXC chemokine receptor 4 pathway.
CONCLUSION—TSP-1 is a potential biomarker of PAD and ECFC-induced angiogenesis, suggesting that TSP-1 modulation might improve local tissue ischemia in this setting. (Clinical trial registrationNCT00377897.)
Abstract Background aims Circulating endothelial progenitor cells and especially endothelial colony-forming cells (ECFCs) are promising candidate cells for endothelial regenerative medicine of ...ischemic diseases, but the conditions for an optimal collection from adult blood must be improved. Methods On the basis of a recently reported vascular niche of ECFCs, we hypothesized that a local ischemia could trigger ECFC mobilization from the vascular wall into peripheral blood to optimize their collection for autologous implantation in critical leg ischemia. Because the target population with critical leg ischemia is composed of elderly patients in whom a vascular impairment has been documented, we also analyzed the impact of aging on ECFC mobilization and vascular integrity. Results After having defined optimized ECFC culture conditions, we studied the effect of forearm ischemia on ECFC numbers and functions in 26 healthy volunteers (13 volunteers ages 20–30-years old versus 13 volunteers ages 60–70 years old). The results show that forearm ischemia induced an efficient local ischemia and a normal endothelial response but did not mobilize ECFCs regardless of the age group. Moreover, we report an alteration of angiogenic properties of ECFCs obtained after forearm ischemia, in vitro as well as in vivo in a hindlimb ischemia murine model. This impaired ECFC angiogenic potential was not associated with a quantitative modification of the circulating endothelial compartment. Conclusions The procedure of local ischemia, although reulting in a preserved endothelial reactivity, did not mobilize ECFCs but altered their angiogenic potential.
The proinflammatory chemokine interleukin 8 exerts potent angiogenic effects on endothelial cells by interacting with its receptors CXCR1 and CXCR2. As thrombin is also a potent inflammatory factor, ...and as endothelial progenitor cells (EPC) express functional PAR‐1 thrombin receptor, we examined whether PAR‐1 stimulation interferes with the IL‐8 pathway in EPC. EPC were obtained from adult blood (AB) and cord blood (CB). The effect of PAR‐1 stimulation by the peptide SFLLRN on IL‐8, CXCR1 and CXCR2 expression was examined by RTQ‐PCR and at the protein level in AB and CB late EPC and in AB early EPC. Specific siRNA was used to knock down PAR‐1 expression. The IL‐8 gene was expressed strongly in AB early EPC and moderately in late EPC. In contrast, CXCR1 and CXCR2 gene expression was restricted to AB early EPC. The IL‐8 level in AB early EPC conditioned medium was high in basal conditions and did not change after PAR‐1 activation. By contrast, IL‐8 secretion by late EPC was low in basal conditions and strongly up‐regulated upon PAR‐1 activation. PAR‐1 activation induced a number of genes involved in activating protein‐1 (AP‐1) and nuclear factor (NF)‐κB pathways. Conditioned medium of PAR‐1‐activated late EPC enhanced the migratory potential of early EPC, and this effect was abrogated by blocking IL‐8. Target‐specific siRNA‐induced PAR‐1 knockdown, and fully inhibited PAR‐1‐induced IL‐8 synthesis. In conclusion, PAR‐1 activation induces IL‐8 synthesis by late EPC. This could potentially enhance cooperation between late and early EPC during neovascularization, through a paracrine effect.
Antiphospholipid antibodies (APA) clinical relevance in COVID-19 is controversial. We aimed to investigate the prevalence and prognostic value of conventional and non-conventional APA in COVID-19 ...patients.
This study was a multi-centric, prospective observational French cohort of patients hospitalized for COVID-19 suspicion.
249 patients were hospitalized for suspected COVID-19, including 154 with confirmed COVID-19 and 95 not confirmed. We found a significant increase in lupus anticoagulant (LA) positivity among COVID-19 positive patients (60.9% versus 23.7% in non-COVID19 patients, p<0.001), while prevalence of conventional (anti-cardiolipin and anti-beta-2-GP1, IgG and IgM isotypes) and non-conventional APA (IgA, anti-phosphatidylserine/prothrombin and anti-prothrombin IgG and IgM) were low in both groups. COVID-19 patients with LA positivity had higher levels of fibrinogen (6.0 IQR 5.0-7.0 versus 5.3 g/L IQR 4.3-6.4, p=0.028) and C-reactive protein (CRP, 115.5 IQR 66.0-204.8 versus 91.8 mg/L IQR 27.0-155.1, p=0.019). Univariate analysis did not show any association between LA positivity and higher risk of venous thromboembolism (VTE, OR 1.02, 95% CI 0.44-2.43, p=0.95) or in-hospital mortality (OR 1.80, 95% CI 0.70-5.05, p=0.24). Unadjusted and adjusted (to CRP, age and sex) Kaplan-Meier survival curves according to LA positivity confirmed the absence of association with VTE or in-hospital mortality (unadjusted: p=0.64 and p=0.26, respectively; adjusted: hazard ratio = 1.13 95% CI 0.48-2.60 and 1.80 95% CI 0.67-5.01).
COVID-19 patients have an increased prevalence of LA positivity associated with biological inflammation markers. However, positive LA at admission is not associated with VTE risk and/or in-hospital mortality.
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