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Sickle Cell Disease and Endothelial Progenitor Cells (EPCs) (DREPANOPEC)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00783627
Recruitment Status : Completed
First Posted : November 3, 2008
Last Update Posted : February 23, 2011
Information provided by:
Assistance Publique - Hôpitaux de Paris

Brief Summary:
Sickle Cell Disease (SCD) is the most prevalent genetic disease of haemoglobin.The underlying abnormality in the red blood cell (RBC) of SCD is the presence of abnormal sickle cell hemoglobin (HbS), which, when deoxygenated, becomes relatively insoluble, forms aggregates with other hemoglobin molecules within the RBC and causes rigid deformation of the cell. Acute pain vaso-occlusive crisis, strokes and acute chest syndrome are the main acute complications, sometimes life-threatening, often leading to organic and functional squeal. Although the common SS form of SCD is a unique gene disorder, the range of the clinical severity is remarkably wide and striking, suggesting that clinical polymorphism is due to modifier genes and environmental factors.Most of the research efforts have been focused on the biology of haemoglobin and of the red cells. Meanwhile, the complex pathophysiology of SCD is undoubtedly influenced by the many physiologic functions of the vascular wall. In line with this hypothesis are several reports of increased circulating levels of endothelium-derived surface molecules in SCD patients suggesting marked endothelial stress in SCD. Similarly, other processes that involve the endothelium, such as leukocyte adhesion and activation, may play a role in vascular occlusion. This accumulation of data raises the unanswered question of the mechanisms of endothelium maintenance and regeneration in SCD. Through these mechanisms, it is likely that function or dysfunction of the vascular endothelium contributes to the overall vascular pathobiology of this disease, which includes recurrent vaso-occlusions, stroke, leg ulcers, chronic organ ischemic damages, and neovascularizing retinopathy that affect nearly one-half (48%) of the surviving patients by the fifth decade.Thus, our groups have combined their respective clinical and biological expertises to test the hypothesis that SCD is a condition of specific endothelial stress and dysfunction upon chronic and Paracystic abnormal interactions with circulating cells and abnormal oxygen delivery to tissues. Specifically, we hypothesize that chronic endothelial stress with detachment of activated endothelial cells require increases mobilisation of the Endothelial Progenitor Cells (EPCs) that maintain endothelial homeostasis to avoid major thromboembolic events and vasospasm. Inappropriate mobilisation or maturation of the EPCs in SCD may participate to the severity of the disease.

Condition or disease Intervention/treatment
Sickle Cell Anemia Procedure: Angiography

Detailed Description:
In the bone marrow, a reservoir of EPCs does exist, which can be mobilized into circulation when needed, for example during ischemia, a situation which may occur in sickle cells disease. These cells are able to reach distant targets and to participate to the neovascularisation processes necessary for tissue and vascular healing. Conversely, abnormalities of the maturation, mobilization or homing processes would contribute to the thrombotic and ischemic risks associated to ischemia. Furthermore, vascular stress such that encountered in SCD leads to the detachment of endothelial cells from the vessels. The number of detached mature circulating endothelial cells (CEC) seems to be related to vascular hurting. The balance between EPCs and CECs would thus be informative of the vascular condition in patients during the progression of the disease. A relatively high level of EPCs would indicate a prominence of a healing neoangiogenesis or vasculogenesis process, while increasing levels of CECs would be indicative severe progression of the disease. Our studies and those published by others indicate that the number of EPCs in peripheral blood is tightly regulated. Indeed, mediators of inflammation could participate to EPC mobilization and to their recruitment to the diseased areas by local activation of the vascular endothelium. In this context, sickle cells disease provokes transient occlusion episodes, leading to a situation of chronic ischemia in different organs, sometimes with acute episodes. This suggests defect of the maintenance of the vascular integrity in these target organs.Within this project, we will compare the number of EPCs and CECs in 25 SCD patients and 25 normal individuals in search of a correlation with the severity of the disease. SCD patients with potential confounding factors that may alter endothelial physiology (drugs, blood transfusions, hydroxyurea therapy) are excluded. In addition, we will analyse and compare in culture and in vivo the phenotypic and functional characteristics of EPCs obtained from patients and controls. We have a working bilateral hypothesis, since we do not know whether SCD subjects have appropriate angiogenic balance (high EPCs/CEC ratio with functional EPCs) to face the situation of endothelial activation and tissue hypoxia induced by SCD. Therefore, we will quantitatively and qualitatively study several distinct biological steps:1. Evaluate the number of colonies generated by the EPCs in culture and their kinetics of appearance in patients (major end point)2. Enumerate EPCs and CECs by flow cytometry using a specific set of markers (CD133, CD146, KDR).3. Measure of the plasma concentrations of PlGF, VEGF, EPO, ET-1, modulators of angiogenesis.4. Test of correlations between these respective characteristics of EPCs with clinical vascular abnormalities of the disease (retinopathy assessed by angiography, nephropathy, leg ulcers) and severity of vaso-occlusive crisis assessed by number and length of hospitalizations during the previous year and during the study.

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Study Type : Observational
Actual Enrollment : 66 participants
Observational Model: Case Control
Time Perspective: Prospective
Official Title: Evaluation of Angiogenic Potential in Sickle Cell Disease. CARACTERIZATION of Endothelial Progenitor Cells
Study Start Date : November 2006
Actual Primary Completion Date : June 2009
Actual Study Completion Date : November 2009

Resource links provided by the National Library of Medicine

Group/Cohort Intervention/treatment
Patient with sickle cell disease
Procedure: Angiography
Angiography done at the J1 visit

Healthy volunteers

Primary Outcome Measures :
  1. Measure the relative levels of endothelial progenitors (EPCs) derived from cultured mononuclear cells in patients and carefully matched healthy subjects at day 0 and after 6 months later (number of endothelial cells colony forming units). [ Time Frame: at day 0 and 6 months ]

Secondary Outcome Measures :
  1. Comparison of the number of circulating EPCs and CECs by FACS. The blood mononuclear cell fraction are depleted from all the haematopoietic cells using a depletion magnetic bead column. The lineage minus population is then subjected to a triple labelling [ Time Frame: at day 1 and at 6 months ]
  2. Correlations tests will be performed between these markers and markers of clinical severity (retinopathy, leg ulcers, number of vaso-occlusive events in the past year, microalbuminuria, leukocyte count, HbF level). [ Time Frame: at day 1 and 6 months ]

Biospecimen Retention:   Samples With DNA
Whole blood

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
Sickle cell patient : followed by the participating center. Healthy volunteers : matched on sex, age and BMI with the patients.

Inclusion Criteria:

  • Age between 18 and 45 yo
  • SS genotype if patient
  • Absence of relative with sickle cell anemia if healthy volunteer.
  • Affiliated to the national health insurance benefit
  • Signature of Informed consent form
  • oral contraceptive regiment with micro or mini estro-progestative (women)

Exclusion Criteria:

  • present or past (or interrupted for less than 3 months) therapy with hydroxyurea
  • Present or recent blood transfusion and/or exchange (in the past 3 months)
  • SC genotype (patients)- BMI > 30 kg/m2
  • Positive serodiagnosis for HIV, HVB, HVC
  • Know allergy to fluorescein (patients)
  • Hemoglobin < 7.5 g/dL
  • Pregnancy confirmed by Beta-HCG test in plasma
  • Menopause
  • Extreme difficulty for adequate venous puncture
  • Smoking for the last month.
  • ALAT or ASAT > 2 x N
  • Hypercholesterolemia (cholesterol total > 2.,2g/L or 6.55 mmol/L),
  • Treatment by statin
  • Diabetes (fasting blood glucose level equal or superior to 6,1 mmol/L)
  • Hypertension (systolic blood pressure > 140 mmHg or diastolic blood pressure > 90 mmHg).

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00783627

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Hopital Tenon, Assistance Publique Hôpitaux de Paris
Paris, France, 75020
Sponsors and Collaborators
Assistance Publique - Hôpitaux de Paris
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Principal Investigator: Pierre Louis THARAUX, MDPH Assistance Publique - Hôpitaux de Paris

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Responsible Party: Christophe Aucan, Department Clinical Research of Developpement Identifier: NCT00783627     History of Changes
Other Study ID Numbers: P 050310
First Posted: November 3, 2008    Key Record Dates
Last Update Posted: February 23, 2011
Last Verified: February 2011
Keywords provided by Assistance Publique - Hôpitaux de Paris:
stem cells
sickle cell
Additional relevant MeSH terms:
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Anemia, Sickle Cell
Anemia, Hemolytic, Congenital
Anemia, Hemolytic
Hematologic Diseases
Genetic Diseases, Inborn