Beta-thalassemia and Microparticles

Assistance Publique Hopitaux De Marseille33 enrolled

Overview

The results will allow us to evaluate the role of MP in the thrombo-embolic risk observed in thalassemic patients and to underline a possible difference between TM and TI. The in vitro and in vivo study of MP in erythrocytes concentrates is a new approach to explore the consequence of transfusion in polytransfused patients. Finally, the identification of a possible relationship between the oxidative stress and the production of MP may lead to the development of specific therapeutical approaches

Microparticles (MP) are intact vesicles derived from cell membranes which arise mainly through cell membrane activation processes and from apoptosis. MP originating from platelets, endothelial cells and monocytes have been most extensively studied, though similar particles can arise from red cells and granulocytes. The ability to form microparticles is an essential part of physiological coagulation.However, MP may play an important procoagulant role in several diseases including sickle cell disease, and paroxysmal nocturnal haemoglobinuria (PNH). Several studies reported the presence of MP in TI and their potential role in the hypercoagulable state. The investigators propose in this study to investigate the presence and origin of MP in TM patients.

Study Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Masking

NONE

Enrollment

Conditions

Thalassemia Major (TM)Thalassemia Intermedia (TI)

Interventions

PhysiopathologyOTHER

Three sequential biological evaluations will be performed for each patient and will consist in : * the dosages of MP carried out by the UMR 608 in Marseille, * the evaluation of the oxidative stress markers and of iron performed in the UMR 773 in Paris-Bichat. In vitro production of MP of transfused red blood cells origin will also be evaluated in erythrocytes concentrates during the storage of the units.

PhysiopathologyOTHER

Eligibility

Sex: ALLMin age: 15 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Patient recorded in the national register of the patients attained by beta-thalassemia (TI) or (TM) * Patient monitoring in one of 5 recruiters centers * Patient more than 15 years * Patient consented and informed Exclusion Criteria: * Blood transfusion dating from less than 3 months for TI * Composite Heterozygotes HbE /beta-thalassemia * pregnant women * other disease

Outcomes

Primary Outcomes

Relationship between TM and TI

* In TM, to quantify the elevation of MP as well as their procoagulant activity, to describe their production kinetic, to determine the transfusional or endogenous origin of erythrocytic MP and finally to compare their characteristics with those found in TI patients. * To study, in TM and TI patients, the relationship between the number, the procoagulant activity of MP and the clinical (thromboembolic episodes,splenectomy, presence of pulmonary hypertension) biological and plasmatic data reflecting the patient's prothrombotic state.

Time frame: 36 months

Secondary Outcomes

Investigate the mechanisms of the elevated production of MP in thalassemias

Studying the correlation between the number, the activity of erythrocytes and platelets derived-MP and the hemolysis, the dyserythropoiesis, the oxidative stress and iron overload markers.