Preparation and characterization of ‘heparinocytes’: erythrocytes with covalently bound low molecular weight heparin

Abstract

In an attempt to create the possibility of stable, long acting, intravascular anticoagulation, low molecular weight heparin was modified by introducing a sulfhydryl group into the molecule (LMWH-SH). Human erythrocytes were covalently grafted with LMWH-SH by the use of a heterobifunctional coupling reagent which reacts with the SH group of LMWH-SH and surface exposed amino groups of erythrocytes now called`heparinocytes' (HC). HC were morphologically indistinguishable from untreated erythrocytes and displayed identical osmotic resistance. The functionality of HC was analyzed by classical coagulation tests in which they dose dependently inhibited clot formation. HC were also functional in recalcified whole blood inhibiting thrombin formation as assessed by the cleavage of the chromogenic substrate S-2238. The system appears applicable as a potential autologous, long-term anticoagulant treatment or prophylaxis.z 2000 Federation of European Biochemical Societies.

Drug delivery by red blood cells: vascular carriers designed by mother nature

“…In theory, coupling drugs to RBC surface may favorably alter their pharmacokinetics (i.e., prolong life-time in circulation) and optimize interaction with components of blood coagulation and fibrinolytic systems accessible from RBC surface. Attempts in this direction included conjugation of heparin to RBC to enhance potency of anticoagulant thromboprophylaxis in patients predisposed to thrombosis256 and conjugation of pro-thrombotic RGD-containing peptide to RBC to design a substitute for platelet infusion in patients predisposed to hemorrhagic disorders 27…”

“…RBC carrying conjugated drugs reported in these studies exerted good functional activities in vitro2,3,256. However, until recently, no attempts to test these drug delivery systems in animal models have been reported, presumably because conjugation of drugs grossly compromised RBC biocompatibility.…”

Delivery of Drugs Bound to erythrocytes: New Avenues for an Old Intravascular Carrier

“…The first attempts to manage thrombosis included conjugating fibrinolytics [19] and heparin [139] to RBCs to prevent thrombosis and clotting agents to mitigate hemorrhagic disorders [17]. …”

“…Biocompatible coupling of PAs to RBCs maintains fibrinolytic activity [17,19,139], prolongs their circulation and minimizes diffusion into the CNS and pre-existing hemostatic plugs. RBC/PA complexes injected in mice and rats circulate orders of magnitude longer than soluble PA counterparts, providing prophylactic delivery of PArier RBC biocompatibility [60,78–82].…”

Erythrocytes as Carriers for Drug Delivery in Blood Transfusion and Beyond

“…Surface loading on RBCs is well suited to deliver agents that modulate hemostasis, including ligands of fibrin[12], heparin[65], and fibrinolytics[66]. For example, RBC carriage prolongs circulation of plasminogen activators (PAs) by orders of magnitude[67], restricts their diffusion into the CNS and pre-existing hemostatic clots, abrogates undesirable interactions with vascular cells[68], and delivers drug to the interior of nascent thrombi[69].…”