Increasing nitric oxide bioavailability fails to improve collateral vessel formation in humanized sickle cell mice

• Authors: Caitlin Lewis, Emory University; Hassan Sellak, Emory University; Laura Hansen, Emory University; Giji Joseph, Emory University; Julian Hurtado, Emory University; David Archer, Emory University; Ho-Wook Jun, University of Alabama Birmingham; Louann Brown, Emory University; W. Robert Taylor, Emory University
• Journal Title: LABORATORY INVESTIGATION
• Volume: Volume 102, Number 8
• Publisher: SPRINGERNATURE | 2022-03-30, Pages 805-813
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1038/s41374-022-00780-0
• Subjects: Engineering, Biomedical
• Keywords: Science & Technology; Life Sciences & Biomedicine; Medicine, Research & Experimental; Pathology; Research & Experimental Medicine; PULMONARY-HYPERTENSION; ARGININE THERAPY; DISEASE; HEMOLYSIS; SYNTHASE; ANEMIA; METABOLISM; CRISIS; MODEL

Abstract

Sickle cell disease (SCD) is associated with repeated bouts of vascular insufficiency leading to organ dysfunction. Deficits in revascularization following vascular injury are evident in SCD patients and animal models. We aimed to elucidate whether enhancing nitric oxide bioavailability in SCD mice improves outcomes in a model of vascular insufficiency. Townes AA (wild type) and SS (sickle cell) mice were treated with either L-Arginine (5% in drinking water), L-NAME (N(ω)-nitro-L-arginine methyl ester; 1 g/L in drinking water) or NO-generating hydrogel (PA-YK-NO), then subjected to hindlimb ischemia via femoral artery ligation and excision. Perfusion recovery was monitored over 28 days via LASER Doppler perfusion imaging. Consistent with previous findings, perfusion was impaired in SS mice (63 ± 4% of non-ischemic limb perfusion in AA vs 33 ± 3% in SS; day 28; P < 0.001; n = 5–7) and associated with increased necrosis. L-Arginine treatment had no significant effect on perfusion recovery or necrosis (n = 5–7). PA-YK-NO treatment led to worsened perfusion recovery (19 ± 3 vs. 32 ± 3 in vehicle-treated mice; day 7; P < 0.05; n = 4–5), increased necrosis score (P < 0.05, n = 4–5) and a 46% increase in hindlimb peroxynitrite (P = 0.055, n = 4–5). Interestingly, L-NAME worsened outcomes in SS mice with decreased in vivo lectin staining following ischemia (7 ± 2% area in untreated vs 4 ± 2% in treated mice, P < 0.05, n = 5). Our findings demonstrate that L-arginine and direct NO delivery both fail to improve postischemic neovascularization in SCD. Addition of NO to the inflammatory, oxidative environment in SCD may result in further oxidative stress and limit recovery.