Safety Evaluation of Hemoglobin-Albumin Cluster “HemoAct” as a Red Blood Cell Substitute

Abstract

A hemoglobin (Hb) wrapped covalently by human serum albumins (HSAs), a core–shell structured hemoglobin-albumin cluster designated as “HemoAct”, is an O2-carrier designed for use as a red blood cell (RBC) substitute. This report describes the blood compatibility, hemodynamic response, and pharmacokinetic properties of HemoAct, and then explains its preclinical safety. Viscosity and blood cell counting measurements revealed that HemoAct has good compatibility with whole blood. Intravenous administration of HemoAct into anesthetized rats elicited no unfavorable increase in systemic blood pressure by vasoconstriction. The half-life of 125I-labeled HemoAct in circulating blood is markedly longer than that of HSA. Serum biochemical tests conducted 7 days after HemoAct infusion yielded equivalent values to those observed in the control group with HSA. Histopathologic inspections of the vital organs revealed no marked abnormality in their tissues. All results indicate that HemoAct has sufficient preclinical safety as an alternative material for RBC transfusion.

Comparison of the Pharmacokinetic Properties of Hemoglobin-Based Oxygen Carriers

“…The Hb–albumin cluster is composed of one Hb in the center and three or four human serum albumins (HSA) in the periphery, and was prepared by a covalent linkage between the Cys34 residue of HSA and the surface Lys amino groups of Hb via a heterobifunctional cross-linker. HemoAct showed good blood compatibility in vitro, and it induced neither hypertension nor toxicity in vivo [89]. Komatsu and colleagues prepared three types of Hb-HSA clusters, Hb-HSA 3 (Hb was enclosed by three HSA molecules), Hb-HSA 4 (Hb was wrapped by four has molecules), and XLHb-HSA 3 (intramolecularly crosslinked Hb was enclosed by three HSA molecules), and compared their pharmacokinetic properties [89,90].…”

“…HemoAct showed good blood compatibility in vitro, and it induced neither hypertension nor toxicity in vivo [89]. Komatsu and colleagues prepared three types of Hb-HSA clusters, Hb-HSA 3 (Hb was enclosed by three HSA molecules), Hb-HSA 4 (Hb was wrapped by four has molecules), and XLHb-HSA 3 (intramolecularly crosslinked Hb was enclosed by three HSA molecules), and compared their pharmacokinetic properties [89,90]. The half-lives of all types of Hb-HSA clusters were more than 20-times and 1.5 times longer than that of Hb and has, respecctively.…”

Artificial Blood for Dogs

“…We reported previously the tissue distribution and metabolism of Hb-HSA 3 cluster in rats3148. The cluster and HSA were similarly distributed in the major organs at 1 h after injection.…”

“…We have recently synthesized a covalent core–shell structured protein cluster comprising a bovine Hb in the center and human serum albumins (HSAs) at the periphery, hemoglobin–albumin cluster (Hb-HSA 3 ), as a unique artificial O 2 -carrier28293031. The Hb nucleus is wrapped covalently with HSA.…”

“…Thereby the surface net charge of the cluster is negative to a marked degree [isoelectric point ( p I): 5.1]. As a consequence, the Hb-HSA 3 cluster shows long circulation persistence and does not engender an acute increase in blood pressure31. This result is ascribed to the electrostatic repulsion between the negatively charged surface of the cluster and glomerular basement membrane around the endothelial cells.…”