5613082 CD34+ HEMATOPOIETIC STEM CELL COUNT AS NOVEL BIOMARKER FOR PREDICTING VASCULAR EVENTS IN EGYPTIAN CHILDREN WITH SICKLE CELL DISEASE

Abstract

Background: Vasoocclusion is the major clinical feature of sickle cell disease (SCD). It results in acute painful vasoocclusive crises and progresses to multiple organ failure (1). Severe SCD is defined as frequent pain, recurrent Acute Chest Syndrome (ACS), stroke and death(2). Therefore, it is essential to identify relevant predictive markers for clinical vascular events. Aim: Evaluation of circulating CD34 as a novel predictive marker of occurrence of vascular events in children with sickle cell disease in their steady state and to relate its levels to other clinical and laboratory parameters of SCD. Methods: 50 patients diagnosed with SCD aged 0.3-13 years old (median 2 years) in their steady state for at least 3 month were enrolled. History with emphasis on neurovascular and peripheral vascular events was taken then hematology, hemolysis, coagulation markers and flow cytometery for quantification of circulating CD34 were withdrawn at inclusion and compared to age and sex matches control then patients were prospectively followed up for 6 months where 2 groups of patients were compared depending on development of vascular events. Results: Results showed statistically significant higher level of circulating CD34+ in patients with SCD compared to control (p <0.001). Patients who developed peripheral vascular events on follow up (n=29) has statistically significant higher level of previous neurovascular events, previous history of vasooclussive crisis(VOC) and previous hospitalization for VOC (p-value 0.015, 0.001 and 0.001 respectively).As for laboratory markers, they have statistically significant higher level of total leucocytic count(TLC), neutrophil count, platelet count and CD34+ level with cut off value of >4340 cell/ ml and higher Time Averaged Mean Flow (TAMMAX)>115cm/sec(p-value 0.015, 0.008, 0.042 and 0.022, 0.028 respectively). There was negative correlation between CD34 and age of diagnosis (p<0.006), hemoglobin level at inclusion (p=0.045), while positively correlated with peripheral vascular events on follow up, TLC, platelet count and bilirubin level at inclusion(p=0.022, 0.01, 0.044, <0.001). Conclusion: Our data showed that circulating CD34 is a potential biomarker for predicting vascular events in children and adolescents with SCD at steady state.