Clinical Trial: Study of Beet Juice for Patients With Sickle Cell Anemia

Study Status: Suspended
Recruit Status: Suspended
Study Type: Interventional

Official Title: Phase 2 Study of Effects of Plasma Nitrite in Sickle Cell Anemia

Brief Summary: The investigators hypothesize that increasing plasma nitrite using dietary nitrate will improve platelet function and red cell deformability and decrease MCHC in patients with sickle cell disease. The investigators will test this hypothesis through administration of daily intake of beetroot juice (Unbeetable - Performance Drink) to patients with sickle cell disease for 28 days. The investigators will evaluate the safety of daily beet root juice intake in patients with sickle cell disease. In addition, the investigators will measure MCHC, red cell deformability, and platelet function (activation and aggregation) in response to daily intake of beet root juice in this patient population.

Detailed Summary:

Sickle cell disease is caused by dysfunction of a mutant form of hemoglobin which polymerizes under hypoxic conditions, sickling the red blood cell. Sickling makes the cells rigid which contributes to vascular occlusion and much morbidity and mortality. Cycles of sickling and unsickling leads to calcium (Ca) influx which activates the gardos channel which pumps out potassium from the cells. Loss of potassium leads to dehydration, poor deformability, and increased mean corpuscular hemoglobin concentration (MCHC) in red blood cells. Increased MCHC leads to increased polymerization. Thus, a significant therapeutic goal for sickle cell disease has been to decrease MCHC by blocking the Ca-influx induced dehydration.

Rifkind and coworkers have shown that the NO+ donor sodium nitrosoprusside (SNP) can block Ca-induced loss of deformability when normal red blood cells are exposed to Ca and a Ca ionophore. The investigators have preliminary data showing that both NO activity donors SNP and nitrite can partially relieve loss of deformability due to cycles of sickling and unsickling in red cells from patients with sickle cell disease.

Low nitric oxide (NO) bioavailabilty secondary to red cell hemolysis has been proposed to contribute to pathology in sickle cell disease. Low NO could lead to poor protection against Ca-induced potassium loss described above. Another consequence of low NO is likely to be increased platelet activation; sickle cell disease is pro-thrombotic disease. NO reduces platelet aggregation and activation. It has been shown that an acute dietary nitrate intervention can reduce platelet aggregation in healthy volunteers. Nitrate is converted to nitrite which is converted to NO in the body.6 Improved platelet function is likely due to increasing NO bioavailability through the nitrate intervention.

Physical symptoms will be assessed either by telephone or in person