Hepatically-metabolized and -excreted artificial oxygen carrier, hemoglobin vesicles, can be safely used under conditions of hepatic impairment

Nanomaterial-related hemoglobin-based oxygen carriers, with emphasis on liposome and nano-capsules, for biomedical applications: current status and future perspectives

Oxygen is necessary for life and plays a key pivotal in maintaining normal physiological functions and treat of diseases. Hemoglobin-based oxygen carriers (HBOCs) have been studied and developed as a replacement for red blood cells (RBCs) in oxygen transport due to their similar oxygen-carrying capacities. However, applications of HBOCs are hindered by vasoactivity, oxidative toxicity, and a relatively short circulatory half-life. With advancements in nanotechnology, Hb encapsulation, absorption, bioconjugation, entrapment, and attachment to nanomaterials have been used to prepare nanomaterial-related HBOCs to address these challenges and pend their application in several biomedical and therapeutic contexts. This review focuses on the progress of this class of nanomaterial-related HBOCs in the fields of hemorrhagic shock, ischemic stroke, cancer, and wound healing, and speculates on future research directions. The advancements in nanomaterial-related HBOCs are expected to lead significant breakthroughs in blood substitutes, enabling their widespread use in the treatment of clinical diseases.

Resuscitative efficacy of hemoglobin vesicles for severe postpartum hemorrhage in pregnant rabbits

We aimed to investigate the resuscitative efficacy of hemoglobin vesicles (HbVs) as a red blood cell (RBC) substitute for the initial treatment of severe postpartum hemorrhage (PPH). Twenty-five pregnant rabbits underwent cesarean section; uncontrolled hemorrhage was induced by transecting the right uterine artery to establish a severe PPH model. During the first 30 min, all rabbits were administered 6% hydroxyethyl starch (HES) of an equivalent volume to the hemorrhage every 5 min. Thereafter, they received any of the following three isovolemic fluids for resuscitation every 5 min: RBCs with platelet-poor plasma (RBC/PPP) (n = 8), 6% HES (n = 7), or HbVs with 25% human serum albumin (n = 10). After surgical hemostasis at 60 min, survival was monitored until 12 h. No rabbits receiving only HES infusion survived beyond 6 h, whereas all rabbits receiving RBC/PPP transfusion survived. The rabbits receiving HbV infusion showed significantly higher mean arterial pressure and hemoglobin levels than the HES-receiving rabbits, and 8 of 10 rabbits survived for 6 h. The HbV group showed significantly higher survival than the HES group but worse survival than the RBC/PPP group. In conclusion, HbV infusion for severe PPH effectively prevents lethal hemorrhagic shock in a pregnant rabbit model.

Long-term pharmaceutical stability of liposome-encapsulated methemoglobin as an antidote for cyanide poisoning

Liposome-encapsulated methemoglobin (metHb@Lipo) has been developed as a novel antidote for cyanide poisoning. Antidotes for lethal acute poisoning should be capable of being easily stored as ready-to-use formulations without temperature restrictions. Here, we investigated the pharmaceutical stability of the metHb@Lipo suspension after one-year storage as a ready-to-use formulation at 4 °C, room temperature (23-28 °C) and 37 °C. The liposomal integrity of metHb@Lipo was observed after one year of storage at all storage temperatures with no physicochemical change or methemoglobin leakage outside the liposome. Furthermore, the encapsulated methemoglobin remained intact without aggregation, fragmentation, denaturation, or dissociation of heme. Fresh and stored metHb@Lipo were equivalent in their binding affinity against cyanide. Moreover, all one-year stored metHb@Lipo suspensions improved the mortality rates of lethal cyanide poisoning mice comparable to fresh metHb@Lipo suspension. Additionally, all stored metHb@Lipo suspensions preserved high biocompatibility, including blood compatibility and the lack of organ toxicity. In conclusion, the metHb@Lipo suspension was a pharmaceutically stable antidote for cyanide poisoning for at least one year without any temperature restrictions.

Pharmaceutical Technology Innovation Strategy Based on the Function of Blood Transport Proteins as DDS Carriers for the Treatment of Intractable Disorders and Cancer

Blood transport proteins are biogenic molecules with unique and interesting inherent characteristics that make up living organisms. As the utilization of their inherent characteristics can be a groundbreaking strategy to resolve and improve several clinical problems, attempts have been made to develop pharmaceutical and biomedical preparations based on blood transport proteins for the treatment and diagnosis of disorders. Among various blood transport proteins, we focus on the immense potential of hemoglobin and albumin to serve as carriers of biomedical gases (oxygen and carbon monoxide) and anticancer agents (low-molecular compounds and antisense oligodeoxynucleotides), respectively, for the development of innovative drug delivery systems (DDS) to treat intractable disorders and solid cancers. In this review, I introduce the pharmaceutical technology, strategies, and application of DDS carriers that have been designed on the basis of the structure and function of hemoglobin and albumin. In addition, the prospect of using hemoglobin and albumin as materials for DDS carriers is discussed.

Evaluation of cytochrome P450-based drug metabolism in hemorrhagic shock rats that were transfused with native and an artificial red blood cell preparation, Hemoglobin-vesicles

Hemoglobin-vesicles (Hb-V) are being developed as red blood cell (RBC) substitutes. In this study, we report on quantitative and qualitative alterations of hepatic cytochrome P450 (CYPs) and the pharmacokinetics of CYP-metabolizing drugs, with a focus on four CYP isoforms (CYP1A2, CYP2C11, CYP2E1 and CYP3A2), after Hb-V resuscitation from a massive hemorrhage. The results of proteome analysis and western blot data indicate that resuscitation with both Hb-V and packed RBC (PRBC) resulted in a decrease in the protein levels of CYPs. Along with a decrease in the protein expression of CYPs, pharmacokinetic studies showed that the elimination of CYP-metabolizing drugs was prolonged in the Hb-V and PRBC resuscitation groups. It is also noteworthy that the CYP-metabolizing drugs in the Hb-V resuscitation group was retained for a longer period compared to the PRBC resuscitation group, and this is attributed to the CYP isoforms having a lower metabolic activity in the Hb-V resuscitation group than that for the PRBC resuscitation group. These findings suggest that resuscitation with Hb-V after a massive hemorrhage has a slight but not clinically significant effect on drug metabolism via CYPs in the liver due to decreased protein levels and the metabolic activity with respect to the CYPs.

Assessing cytochrome P450-based drug-drug interactions with hemoglobin-vesicles, an artificial red blood cell preparation, in healthy rats

Hemoglobin-vesicles (Hb-V), hemoglobin encapsulated within a liposome, were developed as an artificial red blood cell (RBC). When Hb-V becomes clinically available in the future, patients would presumably be co-administered with one or more drugs. Since drug-drug interactions can cause serious adverse effects and impede overall curative effects, evidence regarding the risk associated with drug-drug interactions between Hb-V and such simultaneously administered drugs is needed. Therefore, we report on cytochrome P450 (CYP)-based drug interactions with Hb-V in healthy rats. At 1 day after the saline, Hb-V or packed RBC (PRBC) administration, the blood retention of CYP-metabolizing drugs (caffeine, chlorzoxazone, tolbutamide and midazolam) were moderately prolonged in the case of the Hb-V group, but not the PRBC group, compared to saline group. The results of a proteome analysis revealed that the Hb-V administration had only negligible effects on the protein expression of CYPs in the liver. Hb-V administration, however, clearly suppressed the CYP metabolic activity of the four target CYP isoforms compared with the saline and PRBC group. However, these alterations were nearly recovered at 7 day after the Hb-V administration. Taken together, these results suggest that the administration of Hb-V slightly and transiently affects the CYP-based metabolism of the above drugs.

[Safety Evaluation of Cellular-type Artificial Blood Based on Pharmacokinetic Analysis and Its Use in Medical Gas Delivery]

Hemoglobin vesicles (HbVs) in which human hemoglobin is encapsulated in a phospholipid bilayer membrane (liposome) have been developed as artificial red blood cells. Although the effectiveness of HbVs, including their physicochemical characteristics and pharmacological effects, has been reported, data on the pharmacokinetic properties of HbVs are limited. Previously, we developed two kinds of radiolabeled HbV, ¹²⁵I-HbV and ³H-HbV, in which the internal hemoglobin and lipid membranes were labeled with ¹²⁵I and ³H, respectively. Using these isotope-labeled HbVs, we clarified the detailed pharmacokinetic properties of HbVs in healthy animals and experimental animal disease models of hemorrhagic shock, chronic cirrhosis, and hyperlipidemia. This review describes our previous results regarding the pharmacokinetic properties of HbVs, and we discuss the safety and usefulness of HbVs from the viewpoint of their pharmacokinetic characteristics. Furthermore, we have modified HbVs by employing them as a carbon monoxide (CO) carrier because the hemoglobin inside HbVs reversibly binds to CO, resulting in CO-bound HbVs (CO-HbVs). Here we report the potential of CO-HbVs for the treatment of intractable inflammatory disorders based on their therapeutic efficiency in experimental animal models.

Comparison of the Pharmacokinetic Properties of Hemoglobin-Based Oxygen Carriers

Hemoglobin (Hb) is an ideal material for use in the development of an oxygen carrier in view of its innate biological properties. However, the vascular retention of free Hb is too short to permit a full therapeutic effect because Hb is rapidly cleared from the kidney via glomerular filtration or from the liver via the haptogloblin-CD 163 pathway when free Hb is administered in the blood circulation. Attempts have been made to develop alternate acellular and cellular types of Hb based oxygen carriers (HBOCs), in which Hb is processed via various routes in order to regulate its pharmacokinetic properties. These HBOCs have been demonstrated to have superior pharmacokinetic properties including a longer half-life than the Hb molecule in preclinical and clinical trials. The present review summarizes and compares the pharmacokinetic properties of acellular and cellular type HBOCs that have been developed through different approaches, such as polymerization, PEGylation, cross-linking, and encapsulation.

Long-Term Stored Hemoglobin-Vesicles, a Cellular Type of Hemoglobin-Based Oxygen Carrier, Has Resuscitative Effects Comparable to That for Fresh Red Blood Cells in a Rat Model with Massive Hemorrhage without Post-Transfusion Lung Injury

Hemoglobin-vesicles (HbV), encapsulating highly concentrated human hemoglobin in liposomes, were developed as a substitute for red blood cells (RBC) and their safety and efficacy in transfusion therapy has been confirmed in previous studies. Although HbV suspensions are structurally and physicochemically stabile for least 1-year at room temperature, based on in vitro experiments, the issue of whether the use of long-term stored HbV after a massive hemorrhage can be effective in resuscitations without adverse, post-transfusion effects remains to be clarified. We report herein on a comparison of the systemic response and the induction of organ injuries in hemorrhagic shock model rats resuscitated using 1-year-stored HbV, freshly packed RBC (PRBC-0) and by 28-day-stored packed RBC (PRBC-28). The six-hour mortality after resuscitation was not significantly different among the groups. Arterial blood pressure and blood gas parameters revealed that, using HbV, recovery from the shock state was comparable to that when PRBC-0 was used. Although no significant change was observed in serum parameters reflecting liver and kidney injuries at 6 hours after resuscitation among the three resuscitation groups, results based on Evans Blue and protein leakage in bronchoalveolar lavage fluid, the lung wet/dry weight ratio and histopathological findings indicated that HbV as well as PRBC-0 was less predisposed to result in a post-transfusion lung injury than PRBC-28, as evidenced by low levels of myeloperoxidase accumulation and subsequent oxidative damage in the lung. The findings reported herein indicate that 1-year-stored HbV can effectively function as a resuscitative fluid without the induction of post-transfused lung injury and that it is comparable to fresh PRBC, suggesting that HbV is a promising RBC substitute with a long shelf-life.

Carbon monoxide-bound hemoglobin vesicles ameliorate multiorgan injuries induced by severe acute pancreatitis in mice by their anti-inflammatory and antioxidant properties

Carbon monoxide (CO) has attracted attention as a possible therapeutic agent for affecting anti-inflammatory and antioxidant activities. Previously, CO-bound hemoglobin vesicle (CO-HbV) was developed as a nanotechnology-based CO donor, and its safety profile and therapeutic potential as a clinically applicable carrier of CO were examined in vitro and in vivo. In the present study, the therapeutic efficacy of CO-HbV against severe acute pancreatitis was examined with secondary distal organ-injured model mice that were fed with a choline-deficient ethionine-supplemented diet. A CO-HbV treatment significantly reduced the mortality of the acute pancreatitis model mice compared to saline and HbV. Biochemical and histological evaluations clearly showed that CO-HbV suppressed acute pancreatitis by inhibiting the production of systemic proinflammatory cytokines, neutrophil infiltration, and oxidative injuries in pancreatic tissue. Interestingly, CO-HbV also diminished the subsequent damage to distal organs including liver, kidneys, and lungs. This could be due to the suppression of neutrophil infiltration into tissues and the subsequently enhanced oxidative injuries. In contrast, O₂-bound HbV, the inactive form of CO-HbV, was ineffective against both pancreatitis and distal organ injuries, confirming that CO was directly responsible for the protective effects of CO-HbV in acute pancreatitis. These findings suggest that CO-HbV has anti-inflammatory and antioxidant characteristics of CO and consequently exerts a superior protective effect against acute pancreatitis-induced multiorgan damage.

Biological Responsiveness and Metabolic Performance of Liposome-Encapsulated Hemoglobin (Hemoglobin-Vesicles) in Apolipoprotein E-Deficient Mice after Massive Intravenous Injection

The hemoglobin-vesicle (HbV), a vesicle in which a concentrated human hemoglobin solution is encapsulated, was developed as an artificial oxygen carrier. Although HbV has a favorable safety, metabolic, and excretion performance in healthy animals, the effect of a massive amount of HbV, which also contains a large amount of a lipid component including cholesterol, on physiological response and metabolic performance under hyperlipidemic conditions is unclear. The aim of this study was to evaluate whether administration of HbV causes toxicity in apolipoprotein E-deficient mice (hyperlipidemic model mice). Apolipoprotein E-deficient mice were given a single injection of HbV (2000 mg hemoglobin/kg), and physiological responses and metabolic profiles were monitored for 14 d thereafter. All the mice tolerated the massive amount of HbV and survived, and adequate biocompatibility was observed. Serum biochemical parameters indicate that liver and kidney function were not remarkably affected, and morphological changes in the liver and spleen were negligible. Lipid parameters in serum were significantly increased until 3 d after HbV administration, but recovered within 7 d after the administration. In a pharmacokinetic study, HbV was mainly found distributed in the liver and spleen, and disappeared from the body within 14 d. In conclusion, even under conditions of hyperlipidemia, a massive dose of HbV and its components resulted in favorable biological compatibility, metabolic, and excretion profiles. These findings provide further support for the safety of HbV for clinical use.

Evaluation of a new type of nano-sized carbon monoxide donor on treating mice with experimentally induced colitis

Low concentrations of exogenous carbon monoxide (CO) have been reported to be useful for the treatment of various disorders related to inflammation and oxidative stress. However, a number of obstacles make it difficult to use CO in vivo. Among these are, at high concentrations, it is toxic and the fact that it is difficult to control its delivery in the body. Hemoglobin-encapsulated liposomes, Hemoglobin-vesicles (HbV), have the potential for use as a new type of nano-sized CO donor, referred to as CO-bound HbV (CO-HbV). In this study, we investigated the potential of CO-HbV as a CO donor in terms of toxicity and therapeutic efficacy using an experimental colitis model. Toxicological assessments of CO-HbV showed no severe adverse effects including death, and clinical laboratory tests and histopathological changes remained normal for 28days after the administration of doses up to 1400mgHb/kg. We then evaluated the therapeutic efficacies of CO-HbV on dextran sulfate sodium (DSS)-induced colitis model mice. A single administration of CO-HbV at 3days from beginning of the DSS treatment dramatically improved colitis symptoms, colonic histopathological changes and the duration of survival compared to both saline and HbV administration. In addition, the therapeutic effects of CO-HbV on colitis can be attributed to a decreased level of neutrophil infiltration, the production of pro-inflammatory cytokines and oxidative injuries. Interestingly, it appears that an increase in anti-inflammatory cytokine production contributes, in part, to therapeutic effects of CO-HbV in the treatment of colitis. These safety and efficacy profiles of CO-HbV suggest that it has the potential for use as a drug for treating, not only colitis but also a variety of other disorders associated with inflammation and oxidative stress.

The impact on renal function of fluid resuscitation with hemoglobin vesicle solution in moderate hemorrhagic shock

In this study, hemoglobin vesicle (HbV), a type of artificial oxygen carrier, was infused in a hemorrhagic shock model, and the findings were compared with those of red blood cell (RBC) transfusion to evaluate the effects on blood pressure and renal function. In rats maintained in hemorrhagic shock for 30 min under general anesthesia, either irradiated stored RBCs from the same strain or HbVs were used for resuscitation. Blood pressure, serum creatinine concentration, and creatinine clearance 24 h after shock were measured. At 2 and 24 h after shock, the kidneys were removed, and the heme oxygenase-1 (HO-1) mRNA level was measured. A histopathology study was performed 24 h after shock. In both the RBC and HbV group, blood pressure recovered significantly immediately after fluid resuscitation, and blood pressure 24 h after shock did not differ significantly between the two groups. Serum creatinine concentration and creatinine clearance 24 h after shock did not differ significantly between the two groups. After 24 h, there was no significant difference in HO-1 mRNA between the groups. In the renal histopathology samples taken at 24 h after shock, there were no obvious differences between the two groups. In conclusion, HbV transfusion improved blood pressure in a manner equivalent to RBC transfusion when administered during hemorrhagic shock, and no renal dysfunction was apparent after 24 h.

Removal of cellular-type hemoglobin-based oxygen carrier (hemoglobin-vesicles) from blood using centrifugation and ultrafiltration

The hemoglobin-vesicle (HbV) is an artificial oxygen carrier encapsulating a concentrated hemoglobin solution in a phospholipid vesicle (liposome). During or after transporting oxygen, macrophages capture HbVs in the reticuloendothelial system (RES) with an approximate circulation half-life of 3 days. Animal studies show transient splenohepatomegaly after large doses, but HbVs were completely degraded, and the components were excreted in a few weeks. If a blood substitute is used for emergency use until red blood cell transfusion becomes available or for temporary use such as a priming fluid for an extracorporeal circuit, then one option would be to remove HbVs from the circulating blood without waiting a few weeks for removal by the RES. Using a mixture of beagle dog whole blood and HbV, we tested the separation of HbV using a centrifugal Fresenius cell separator and an ultrafiltration system. The cell separator system separated the layers of blood cell components from the HbV-containing plasma layer by centrifugal force, and then the HbV was removed from plasma phase by the ultrafiltration system. The HbVs (250-280 nm) are larger than plasma proteins (< 22 nm diameter) but smaller than blood cell components (> 3 µm). The size of HbVs is advantageous to be separated from the original blood components, and the separated blood components can be returned to circulation.

Fluid resuscitation with hemoglobin vesicles prevents Escherichia coli growth via complement activation in a hemorrhagic shock rat model

Hemoglobin vesicles (HbVs) could serve as a substitute for red blood cells (RBCs) in resuscitation from massive hemorrhage. A massive transfusion of RBCs can increase the risk of infection, which is not caused by contaminating micro-organisms in the transfused RBCs but by a breakdown of the host defense system. We previously found that complement activity was increased after resuscitation with HbVs at a putative dose in a rat model of hemorrhagic shock. It is known that complement system plays a key role in host defense in the embryonic stage. Therefore, the objective of this study was to address whether the suppression of bacterial infections in hemorrhagic shock rats was a result of increased complement activity after massive HbV transfusion. For this purpose, Escherichia coli were incubated with plasma samples obtained from a rat model of hemorrhagic shock resuscitated by HbVs or RBCs, and bacterial growth was determined under ex vivo conditions. As a result, E. coli growth was found to be suppressed by increased complement activity, mediated by the production of IgM from spleen. However, this antibacterial activity disappeared when the E. coli were treated with complement-inactivated plasma obtained from splenoctomized rats. In addition, the resuscitation of HbVs from hemorrhagic shock increased the survival rate and viable bacterial counts in blood in cecum ligation and puncture rats, a sepsis model. In conclusion, the resuscitation of HbVs in the rat model of hemorrhagic shock suppresses bacterial growth via complement activation induced by IgM.