Red blood cell aggregation, aggregate strength and oxygen transport potential of blood are abnormal in both homozygous sickle cell anemia and sickle-hemoglobin C disease

Abstract

BackgroundRecent evidence suggests that red blood cell aggregation and the ratio of hematocrit to blood viscosity (HVR), an index of the oxygen transport potential of blood, might considerably modulate blood flow dynamics in the microcirculation. It thus seems likely that these factors could play a role in sickle cell disease. Design and MethodsWe compared red blood cell aggregation characteristics, blood viscosity and HVR at different shear rates between sickle cell anemia and sickle cell hemoglobin C disease (SCC) patients, sickle cell trait carriers (AS) and control individuals (AA). ResultsBlood viscosity determined at high shear rate was lower in sickle cell anemia (n=21) than in AA (n=52), AS (n=33) or SCC (n=21), and was markedly increased in both SCC and AS. Despite differences in blood viscosity, both sickle cell anemia and SCC had similar low HVR values compared to both AA and AS. Sickle cell anemia (n=21) and SCC (n=19) subjects had a lower red blood cell aggregation index and longer time for red blood cell aggregates formation than AA (n=16) and AS (n=15), and a 2 to 3 fold greater shear rate required to disperse red blood cell aggregates. ConclusionsThe low HVR levels found in sickle cell anemia and SCC indicates a comparable low oxygen transport potential of blood in both genotypes. Red blood cell aggregation properties are likely to be involved in the pathophysiology of sickle cell disease: the increased shear forces needed to disperse red blood cell aggregates may disturb blood flow, especially at the microcirculatory level, since red blood cell are only able to pass through narrow capillaries as single cells rather than as aggregates.Key words: sickle cell disease, red blood cell aggregation, viscosity, red blood cell deformability. Citation: Tripette J, Alexy T, Hardy-Dessources M-D, Mougeneld D, Beltan E, Chalabi T, Chout

Hematologic and hemorheological determinants of resting and exercise-induced hemoglobin oxygen desaturation in children with sickle cell disease

“…A high RBC disaggregation threshold means that RBC aggregates are tightly bound. 20 This may increase flow resistance, promote arteriovenous shunts and disturb microcirculation at the entry of the pulmonary capillaries where RBC aggregates need to be fully dispersed before they can enter and negotiate small capillaries to promote adequate gas exchange between the lungs and RBC. 46 A major limitation of the present study is the absence of a healthy control group.…”

“…20,22,23,39 Therefore, SC and SS children were analyzed separately. Part of the results described here were previously included in a report on the initial SAPOTILLE cohort.…”

“…2,6,11 Sickle cell disease is characterized by severe hemorheological abnormalities that play a role in the pathophysiology of several acute and chronic complications. [16][17][18][19][20][21][22][23][24] Experimental work in non-SCD subjects and mathematical modeling strongly suggest that hemorheological impairment may contribute to hemoglobin oxygen desaturation at rest. 25 Hematocrit and red blood cell (RBC) deformability have been demonstrated to modulate pulmonary diffusing capacity.…”

Grounding the Human Body during Yoga Exercise with a Grounded Yoga Mat Reduces Blood Viscosity

“…Another factor is the ability of RBCs to deform and bend to more easily pass through capillaries [24]. The speed of the flow, partly a function of vessel diameter, also causes vis-cosity to change.…”

“…The older red blood cells also lose their ability to deform which creates a problem because without being able to bend through the capillaries, they cannot get to the cells. This decreases oxygen and nutrient delivery to the cells and eventually causes capillary damage [24].…”