Objective: To examine the in vitro and in vivo attributes of aspartame and to determine its efficacy for treating sickle cell anemia.
Rationale: Aspartame (l-aspartyl-l-phenylalanine methyl ester) binds with 2 human Bence Jones proteins. The proteins (Mcg and Sea) showed phenylalanine penetrating into hydrophobic binding sites. This aspartame property suggested a potential to interfere with sickle hemoglobin fibril formation.
Methods: For the in vitro studies, blood from 20 subjects monitored for sickle cell anemia was collected in heparinized tubes. Specimens were divided in thirds and aspartame was added to 2 tubes to yield a 1 mg/mL or 2 mg/mL concentration. Sickled cells that were present after a drop from each aliquot was added to a fresh 2% metabisulfite solution were counted 3 times. For the in vivo studies, 23 subjects from the Sickle Cell Clinic (University of Oklahoma Health Sciences Center, Oklahoma City, Okla) consented to participate in a randomized single-dose administration of 1.5, 3.0, or 6 mg/kg aspartame. Heparinized blood was obtained at 0, 30, 60, 120, 240, 480, and 1440 minutes after aspartame administration. Specimens were counted in a blinded manner by means of the technique used for the in vitro method, but a photomicrograph of 1 field from each triplicate count was made. The pictures were marked and were computer counted.
Results: For the in vitro studies, sickled cells decreased from 28% to < 14% when 1 mg/mL aspartame was added and decreased further with 2 mg/mL. For the in vivo studies, a decreased number of sickled cells in homozygous blood (HbSS) were observed after oral administration of aspartame. Sickling was inhibited by 6 mg/kg aspartame for at least 6 hours in 15 subjects with HbSS anemia.
Conclusions: Further evaluations of the efficacy of aspartame for sickle crisis and crisis prevention appears to be warranted.