Multi-Modal Mechanisms and Anti-Sickling of Novel Sulfated Non-Anticoagulant Low Molecular Weight Heparin in Sickle Cell Disease

• Published in: Blood 2018-11, Vol.132 (Supplement 1), p.265-265
• Main Authors: Mousa, Shaker A, Darwish, Noureldien Hassan Elsayed, Muralidharan-Chari, Vandhana, Qari, Mohamed, Qiukan, Chen, Russell, J Eric, Abdulmalik, Osheiza
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2018-99-115121

The pathogenesis of Sickle Cell Disease (SCD) comprises a complex interplay of factors associated with vascular endothelial activation, intense inflammation, and increased sickle cell adhesion. Microvascular occlusion in SCD is initiated by adhesion of sickle red blood cells (RBCs) to the endothelium, leading to acute painful vasoocclusive crisis (VOC) and clinical morbidity. Current treatment strategies remain sub-optimal and are limited by significant side effects. The inherent complexity of SCD makes it unlikely that a single therapeutic strategy will be universally beneficial. We have previously shown that the low molecular weight heparin (LMWH) tinzaparin significantly shortened both duration of VOC crisis and hospitalizations by ~40%, and resulted in statistically significant and rapid reduction of pain). However, safety concerns associated with the narrow therapeutic index (bleeding risks) of LMWH are a major barrier to dose escalation/optimization of treatments. We have developed a novel sulfated non-anticoagulant LMWH, named S-NACH, with an extensive range of bioactivities that would constitute a multi-modal approach to management of SCD. We generated and significantly optimized S-NACH for VOC to: 1) exert its beneficial activities without causing hemostatic (bleeding) side effects that are associated with the clinical use of LMWHs; and 2) incorporate an additional, potent direct anti-sickling property besides its anti-selectin and anti-inflammatory activities. We conducted in vitro and in vivo investigations on the efficacy of S-NACH on the biophysical properties of RBCs. For the in vitro study, 21 subjects comprising 12 SCD patients with hemoglobin (Hb) SS on hydroxurea and 9 normal subjects with Hb AA of both sexes and of different ages were randomly recruited. To assess the effects of S-NACH on the sickling, the SS blood samples were incubated under hypoxia (2% O2 gas, balance N2 gas) at 37°C for 1.5 h, in the absence (control) or presence of 1, 5, or 10 ug/mL of S-NACH or LMWH. For the in vivo study, we obtained pre-treatment samples from Townes' SCD mice (n=6 mice/treatment group) and treated the mice subcutaneously with PBS or 30-100 mg/kg S-NACH. Two hours after treatment, blood samples were evaluated for the percentage of sickled cells in pre- and post-administration samples using Leishman's stain and wet smears. Incubation with S-NACH in vitro under hypoxia showed a dose-dependent, significant inhibition of sickling (up to 80%) in sample