Abstract 1642

Sickle cell disease is characterized by recurring episodes of hemolysis and painful vasoocclusion, which leads to ischemia-reperfusion injury and organ damage. Recently, the roles of heme-induced oxidative stress, nitric oxide consumption, endothelial cell activation, and inflammation in sickle cell disease have been recognized, in part because of the development of transgenic murine models of this condition. These mouse models provide insights into the pathophysiology of human sickle cell disease and the development of new therapeutic approaches. However, hemolytic rates and disease severity vary considerably between mouse models. Ferrous (Fe2+) hemoglobin (Hb) is easily oxidized in circulation to ferric (Fe3+) Hb, which readily releases free heme. Free heme is degraded by heme oxygenase which produces carbon monoxide (CO) as a byproduct. Endogenous CO production has been used as a measure of in vivo hemolysis in humans and mice, but there have been no reports of endogenous CO production in sickle mouse models. VCO was measured in sickle mouse models using a previously described rebreathing technique t (Levitt et al. J Lab Clin Med 113:241-247). Expired CO levels were highest in Hb-S knock-in Townes-SS sickle mice, almost 7-fold higher than normal control Townes-AA mice (p<0.05). Expired CO also was significantly (p<0.05) higher in HbS-BERK mice compared to normal control HbA-BERK. Injection of phenylhydrazine or hemin into normal C57BL/6 mice also raised expired CO levels 24 hours after injection (p<0.05). Expired CO levels were not significantly higher than controls in the New York, S+S-Antilles, het-BERK and Townes-AS models. These data confirm that hemolytic rates differ markedly between models. Additional data will be presented on the effects of inhaled CO on expired CO and the hemolytic rate in the Townes-SS model.

Table
Mean Expired COSEM Expired CO
Mice
n
(nmol/h/g)
(nmol/h/g)
C57BL/6 6 0.980 0.153 
C57BL/6 + Phenylhydrazine 4 5.229a 0.610 
C57BL/6 + Hemin 5 2.057a 0.178 
New York 4 1.305 0.278 
S+S-Antilles 4 0.991 0.106 
HbA-BERK 12 1.264 0.168 
het-BERK 7 1.489 0.405 
HbS-BERK 6 4.627b 0.796 
Townes-AA 4 0.924 0.123 
Townes-AS 4 1.272 0.119 
Townes-SS 4 6.334c 0.541 
Mean Expired COSEM Expired CO
Mice
n
(nmol/h/g)
(nmol/h/g)
C57BL/6 6 0.980 0.153 
C57BL/6 + Phenylhydrazine 4 5.229a 0.610 
C57BL/6 + Hemin 5 2.057a 0.178 
New York 4 1.305 0.278 
S+S-Antilles 4 0.991 0.106 
HbA-BERK 12 1.264 0.168 
het-BERK 7 1.489 0.405 
HbS-BERK 6 4.627b 0.796 
Townes-AA 4 0.924 0.123 
Townes-AS 4 1.272 0.119 
Townes-SS 4 6.334c 0.541 
a

p<0.05 versus C57BL/6;

b

p<0.05 versus HbA-BERK;

c

p<0.05 versus Townes-AA

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Disclosures:

Belcher:Sangart: Consultancy, Research Funding. Vercellotti:Sangart: Consultancy, Research Funding.

Topics:
carbon monoxide, hemolysis, mice, transgenic, sickle cell anemia, heme, hemoglobin a, hemin, hemoglobin, sickle, heme oxygenase (decyclizing), hemoglobin

Author notes

*

Asterisk with author names denotes non-ASH members.

© 2010 by The American Society of Hematology
2010
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