Rational design of low-molecular weight heparins with improved
            <i>in</i>
            <i>vivo</i>
            activity

Sundaram, Mallik; Qi, Yiwei; Shriver, Zachary; Liu, Dongfang; Zhao, Ganlin; Venkataraman, Ganesh; Langer, Robert; Sasisekharan, Ram

doi:10.1073/pnas.252643299

Cited by 84 publications

(47 citation statements)

References 34 publications

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“…16,41 In this regard, a small uncontrolled study concluded that minidose UFH could reduce the frequency of sickle cell pain crises. 76 While the potential side effects and requirement for injectable administration limit the therapeutic potential of UFH for preventing painful sickle cell vasoocclusion, 48 more detailed molecular understandings of the structural determinants the Pselectin blocking activity 77 and the technology required to tailor heparin activities according to desired effects 78 offer promise for the future use of sulfated anionic polysaccharides for preventing painful vasoocclusion in sickle cell disease. Consideration is now warranted for this therapeutic approach to preventing pain crises in patients with sickle cell disease.…”

Section: Discussionmentioning

confidence: 99%

The contribution of endothelial cell P-selectin to the microvascular flow of mouse sickle erythrocytes in vivo

Embury

Matsui²,

Ramanujam³

et al. 2004

Blood

126

121

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Microvascular occlusion in sickle cell disease can be initiated by adhesion of sickle red blood cells (RBCs) to the endothelium. Our objective in this study was to verify the relevance in vivo of our discovery that sickle RBCs adhere abnormally to endothelial P-selectin in vitro. We used computer-assisted intravital microscopy to characterize RBC flow velocity (V RBC ) in mice. We found faster V RBC of sickle RBCs in P-selectin knock-out and control mice than in sickle cell mice, which have increased endothelial cell P-selectin expression. Agonist peptide for murine protease-activated receptor-1 (PAR-1), which selectively activates mouse endothelial cells but not platelets, was used to assess the effects of endothelial cell Pselectin on microvascular flow. Suffusion of venules with this agonist stopped flow promptly in normal and sickle mice but not in P-selectin knock-out mice or in control mice pretreated with anti-P-selectin monoclonal antibody or unfractionated heparin (UFH). Agonist-induced slowing of flow was reversed rapidly by suffusion with UFH, provided flow had not already stopped. We conclude that endothelial cell P-selectin contributes to the microcirculatory abnormalities in sickle cell disease and that blocking Pselectin may be useful for preventing painful vasoocclusion in sickle cell disease. ( IntroductionMost of the morbid consequences of sickle cell disease are caused by the impairment of blood flow in the microvasculature. 1 Traditional understandings attribute the microvascular occlusion to an increase in blood viscosity caused by intraerythrocytic polymerization of deoxygenated sickle hemoglobin and the consequent sickling and rigidification of red blood cells (RBCs). 2 Kinetic considerations predict that, in the absence of preexisting intraerythrocytic polymer, impairment of blood viscosity will occur after the RBC has entered into veins too large to be occluded by rigid sickled RBCs 3 and that polymerization will occur within vessels small enough to be occluded by individual sickled RBCs only when their transit through the microcirculation is delayed.Among the factors that can prolong the transit time of sickle RBCs through the microvasculature are several polymerizationindependent processes, including vascular constriction, coagulation, inflammation, and cellular adhesion. 4 Experimental evidence supports a 2-step mechanism of vasoocclusion initiated by the binding of an adhesive subset of sickle RBCs to the vascular endothelium and completed by the logjamming of more rigid sickle RBCs behind the adherent nidus. 5 This discovery has provided an understanding of the onset of painful vasoocclusion that is lacking from detailed explications of hemoglobin S polymerization and RBC sickling and notions of systemic deoxygenation 6 and inspired a profusion of research into mechanisms of adhesion and adhesion-blocking therapies. 7,8 The expression of cytoadhesion molecules on endothelial cells isolated from the circulating blood of patients with sickle cell disease 9 and on intact endothelial c...

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Section: Discussionmentioning

confidence: 99%

The contribution of endothelial cell P-selectin to the microvascular flow of mouse sickle erythrocytes in vivo

Embury

Matsui²,

Ramanujam³

et al. 2004

Blood

126

121

View full text Add to dashboard Cite

show abstract

“…Despite its widespread use, native, unfractionated heparin has many limitations, such as interpatient variablility, nonspecific protein binding, unstable pharmacokinetics, and potential side effects such as hemorrhage and heparin-induced thrombocytopenia (11). The variability of heparin arises from its complex molecular structure, intrinsic polydisperity (molecular mass ranges from 3 to 30 kDa) and heterogeneity of samples (only one in three molecules contains the active AT-III-binding site) (12).…”

mentioning

confidence: 99%

Monitoring of heparin and its low-molecular-weight analogs by silicon field effect

Milović

Behr

Godin

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Heparin is a highly sulfated glycosaminoglycan that is used as an important clinical anticoagulant. Monitoring and control of the heparin level in a patient's blood during and after surgery is essential, but current clinical methods are limited to indirect and off-line assays. We have developed a silicon field-effect sensor for direct detection of heparin by its intrinsic negative charge. The sensor consists of a simple microfabricated electrolyte-insulatorsilicon structure encapsulated within microfluidic channels. As heparin-specific surface probes the clinical heparin antagonist protamine or the physiological partner antithrombin III were used. The dose-response curves in 10% PBS revealed a detection limit of 0.001 units͞ml, which is orders of magnitude lower than clinically relevant concentrations. We also detected heparin-based drugs such as the low-molecular-weight heparin enoxaparin (Lovenox) and the synthetic pentasaccharide heparin analog fondaparinux (Arixtra), which cannot be monitored by the existing near-patient clinical methods. We demonstrated the specificity of the antithrombin III functionalized sensor for the physiologically active pentasaccharide sequence. As a validation, we showed correlation of our measurements to those from a colorimetric assay for heparin-mediated anti-Xa activity. These results demonstrate that silicon field-effect sensors could be used in the clinic for routine monitoring and maintenance of therapeutic levels of heparin and heparin-based drugs and in the laboratory for quantitation of total amount and specific epitopes of heparin and other glycosaminoglycans.heparin sensors ͉ label-free sensing ͉ medical devices ͉ enoxaparin ͉ fondaparinux

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“…An anti-Xa assay was performed by modification of the amidolytic method (17) with a Coatest heparin test kit by using S-2222 as the chromogenic substrate (Diapharma Group, West Chester, OH). The detailed procedure has been described (15).…”

Section: Methodsmentioning

confidence: 99%

“…The antithrombotic effects of inhaled LMWH were evaluated by Wessler's stasis model (18) adapted for the rat by using Russell Viper Venom as the thrombogenic stimulus (19). The procedure was performed as described (15). Briefly, 1 h after pulmonary inhalation or s.c. injection of LMWH, a laparot- …”

Section: Methodsmentioning

confidence: 99%

Delivery of therapeutic levels of heparin and low-molecular-weight heparin through a pulmonary route

Zhao

Liu

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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Although heparin and low-molecular-weight heparins (LMWH) have been widely used clinically as anticoagulants, their broader use has been limited by the lack of noninvasive delivery methods for this class of molecules. In this study, we demonstrate an efficient, rapid, and reproducible delivery system for heparin through the lungs that is not confined to particles of a certain geometric or aerodynamic diameter. Importantly, blood levels after intrapulmonary administration of either heparin or LMWH were comparable to that of s.c. administration but are characterized by a more rapid onset of action (t 1/2 ‫؍‬ 40 min vs. 2.5 h, respectively). Furthermore, we show in animal models, that inhaled heparin species efficiently inhibit diseases such as thrombosis and emphysema, and that the repetitive inhalation of formulated LMWH results in no observable toxicity from the delivery of reproducible systemic levels of heparin or LMWH.

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Rational design of low-molecular weight heparins with improved in vivo activity

Cited by 84 publications

References 34 publications

The contribution of endothelial cell P-selectin to the microvascular flow of mouse sickle erythrocytes in vivo

The contribution of endothelial cell P-selectin to the microvascular flow of mouse sickle erythrocytes in vivo

Monitoring of heparin and its low-molecular-weight analogs by silicon field effect

Delivery of therapeutic levels of heparin and low-molecular-weight heparin through a pulmonary route

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