Safety and efficacy of human polymerized hemoglobin on guinea pig resuscitation from hemorrhagic shock

Abstract

For the past thirty years, hemoglobin-based oxygen carriers (HBOCs) have been under development as a red blood cell substitute. Side-effects such as vasoconstriction, oxidative injury, and cardiac toxicity have prevented clinical approval of HBOCs. Recently, high molecular weight (MW) polymerized human hemoglobin (PolyhHb) has shown positive results in rats. Studies have demonstrated that high MW PolyhHb increased O2 delivery, with minimal effects on blood pressure, without vasoconstriction, and devoid of toxicity. In this study, we used guinea pigs to evaluate the efficacy and safety of high MW PolyhHb, since like humans guinea pigs cannot produce endogenous ascorbic acid, which limits the capacity of both species to deal with oxidative stress. Hence, this study evaluated the efficacy and safety of resuscitation from severe hemorrhagic shock with high MW PolyhHb, fresh blood, and blood stored for 2 weeks. Animals were randomly assigned to each experimental group, and hemorrhage was induced by the withdrawal of 40% of the blood volume (BV, estimated as 7.5% of body weight) from the carotid artery catheter. Hypovolemic shock was maintained for 50 min. Resuscitation was implemented by infusing 25% of the animal’s BV with the different treatments. Hemodynamics, blood gases, total hemoglobin, and lactate were not different before hemorrhage and during shock between groups. The hematocrit was lower for the PolyhHb group compared to the fresh and stored blood groups after resuscitation. Resuscitation with stored blood had lower blood pressure compared to fresh blood at 2 h. There was no difference in mean arterial pressure between groups at 24 h. Resuscitation with PolyhHb was not different from fresh blood for most parameters. Resuscitation with PolyhHb did not show any remarkable change in liver injury, inflammation, or cardiac damage. Resuscitation with stored blood showed changes in liver function and inflammation, but no kidney injury or systemic inflammation. Resuscitation with stored blood after 24 h displayed sympathetic hyper-activation and signs of cardiac injury. These results suggest that PolyhHb is an effective resuscitation alternative to blood. The decreased toxicities in terms of cardiac injury markers, vital organ function, and inflammation following PolyhHb resuscitation in guinea pigs indicate a favorable safety profile. These results are promising and support future studies with this new generation of PolyhHb as alternative to blood when blood is unavailable.

The Molecular Size of Bioengineered Oxygen Carriers Determines Tissue Oxygenation in a Hypercholesterolemia Guinea Pig Model of Hemorrhagic Shock and Resuscitation

“…To date, rodent models of hemorrhagic shock and acute trauma show that some PolyhHb solutions may be beneficial as O 2 -carrying therapeutics, as they are attractive alternatives when blood transfusion is not an option. Furthermore, these preclinical studies are strengthened by data showing polymerized Hb equivalence to fresh blood and superiority to stored blood, offering an intriguing proof of concept. ,, However, these experiments are performed using unfractionated, and thus polydisperse, PolyhHb and do not study a toxicology-based model of underlying disease designed to predict effectiveness but also safety. Our prior work in a 25% blood volume exchange transfusion guinea pig model evaluating size-bracketed PolyhHbs shows bracket-specific characteristics, such as the rates of oxidation, O 2 offloading, and clearance were associated with PolyhHb MW .…”

“…Studies have demonstrated that PolyhHb filtered between 500 kDa and 0.2 μm avoid the adverse effects seen in clinical trials and have shown a proof of concept as an effective resuscitative fluid in a guinea pig model of hemorrhagic shock. 25 Investigation into the effect of MW on pharmacokinetics, pharmacodynamics, and toxicity of PolyhHb fractionated into smaller MW brackets was performed in a guinea pig exchange transfusion model. This study identified the MW bracket between 500−750 kDa as being optimal as a long circulating material based on pharmacokinetic, hemodynamic, and cardiac conduction analyses, 26 thus warranting further investigation in a translational toxicology model.…”

“…This technique can rapidly generate materials for in vitro and in vivo screening to assess Hb interactions with endothelial and subendothelial compartments, and reduce reactivity with ligands at the heme-centered iron. − The adverse effects seen in phase III trials with commercial versions of polymerized human Hb (PolyhHb) is most likely attributed to the presence of low MW species (<500 kDa) that still retain a tendency to extravasate blood vessels like cell-free Hb. Studies have demonstrated that PolyhHb filtered between 500 kDa and 0.2 μm avoid the adverse effects seen in clinical trials and have shown a proof of concept as an effective resuscitative fluid in a guinea pig model of hemorrhagic shock . Investigation into the effect of MW on pharmacokinetics, pharmacodynamics, and toxicity of PolyhHb fractionated into smaller MW brackets was performed in a guinea pig exchange transfusion model.…”

Silk Fibroin Particles as Carriers in the Development of Hemoglobin‐Based Oxygen Carriers

“…[21] To address these challenges, strategies to increase the molecular diameter of the HBOC and limit free hemoglobin in circulation have become requirements in the design of modern HBOCs. These strategies include chemical cross-linking of hemoglobin, [22,23] polymerization of hemoglobins, [24][25][26] and encapsulation of hemoglobin in liposome and nano-and microparticle systems. [27,28] Liposome encapsulated hemoglobin's have demonstrated many of the desired design criteria for an alternative oxygen carrier, including an absence of blood group antigens and blood-borne pathogens, and a prolonged storage capacity.…”

Silk Fibroin Particles as Carriers in the Development of All-Natural Hemoglobin-Based Oxygen Carriers (HBOCs)

“…18 To address these challenges, strategies to increase the molecular diameter of the HBOC and limit free hemoglobin in circulation have become requirements in the design of modern HBOCs. These strategies include chemical crosslinking of hemoglobin, 19,20 polymerization of hemoglobin and crosslinked hemoglobins, [21][22][23] and encapsulation of hemoglobin in liposome and nano-and microparticle systems. 24,25 Liposome encapsulated hemoglobins have demonstrated many of the desired design criteria for an alternative oxygen carrier, including absence of blood group antigens and blood-borne pathogens and a prolonged storage capacity.…”