HBOC-201 as an alternative to blood transfusion: efficacy and safety evaluation in a multicenter phase III trial in elective orthopedic surgery

Transfusion management and hemoglobin-based oxygen carrier treatment in a patient with anti-Rh17 antibody

BACKGROUND

A 54-year-old Hispanic OPos female with known history of anti-Rh17 antibodies was diagnosed with Philadelphia-Chromosome positive (Ph+) acute lymphoblastic leukemia (ALL). Rh17, also known as Hr0, is a high-frequency antigen composed of several epitopes on the RhCE protein. Anti-Rh17 antibodies can be made by individuals with missing or varied C/c, E/e antigens. Anti-Rh17 antibodies are clinically significant given multiple case reports of hemolytic disease of the fetus and newborn (HDFN). Finding compatible units for patients with anti-Rh17 can be particularly difficult given that only 1 in 100,000 people are Rh17 negative.

STUDY DESIGN AND METHODS

Search for compatible units was conducted by the American Rare Donor Program (ARDP) with no leads. After chemotherapy induction and despite erythropoiesis stimulating agent administration, the patient's hemoglobin continued to trend down to a nadir of 2.8 g/dL. Here we report transfusion of incompatible pRBC to this patient with critically symptomatic anemia. HBOC-201 (Hemopure) was obtained and administered under an emergency compassionate/expanded access designation from the Food and Drug Administration (FDA) under an emergency Investigational New Drug (IND) application.

RESULTS AND DISCUSSION

Overall difficulties in this case included the challenge of finding compatible units, dilemma of transfusing incompatible units in a patient with severe anemia and obtaining alternatives to blood products. This case report demonstrates the successful use of HBOC-21 in treating life-threatening anemia.

Tracking Research on Hemoglobin-Based Oxygen Carriers: A Scientometric Analysis and In-Depth Review

Numerous studies on the formulation and clinical applications of novel hemoglobin-based oxygen carriers (HBOCs) are reported in the scientific literature. However, there are fewer scientometric analysis related to HBOCs. Here, we illustrate recent studies on HBOCs using both a scientometric analysis approach and a scope review method. We used the former to investigate research on HBOCs from 1991 to 2022, exploring the current hotspots and research trends, and then we comprehensively analyzed the relationship between concepts based on the keyword analysis. The evolution of research fields, knowledge structures, and research topics in which HBOCs located are revealed by scientometric analysis. The elucidation of type, acting mechanism, potential clinical practice, and adverse effects of HBOCs helps to clarify the prospects of this biological agent. Scientometrics analyzed 1034 publications in this research field, and these findings provide a promising roadmap for further study.

Biocompatibility of the oxygen carrier polymerized human hemoglobin towards HepG2/C3A cells

Hemoglobin (Hb) based oxygen carriers (HBOCs) are designed to minimize the toxicity of extracellular Hb, while preserving its high oxygen-carrying capacity for oxygen delivery to cells. Polymerized human Hb (PolyHb) is a novel type of nanosized HBOC synthesized via glutaraldehyde-mediated crosslinking of free Hb, and which preserves the predominant quaternary state during the crosslinking reaction (low oxygen affinity tense (T) quaternary state PolyHb is synthesized at 0% Hb oxygen saturation, and high oxygen affinity relaxed (R) quaternary state PolyHb is synthesized at 100% Hb oxygen saturation). Major potential applications for PolyHbs, and HBOCs in general, include oxygenation of bioreactor systems containing large liver cell masses, and ex-vivo perfusion preservation of explanted liver grafts. The toxicity of these compounds toward liver cells must be evaluated before testing their use in these complex systems for oxygen delivery. Herein, we characterized the effect of PolyHbs on the hepatoma cell line HepG2/C3A, used as a model hepatocyte and as a cell line used in some investigational bioartificial liver support devices. HepG2/C3A cells were incubated in cell culture media containing PolyHbs or unmodified Hb at concentrations up to 50 mg/mL and for up to 6 days. PolyHbs were well tolerated at a dose of 10 mg/mL, with no significant decrease in cell viability; however, proliferation was inhibited as much as 10-fold after 6 days of exposure at 50 mg/mL. Secretion of albumin, and urea, as well as glucose and ammonia removal were measured in presence of 10 mg/mL of PolyHbs or unmodified Hb. In addition, methoxy- and ethoxy-resorufin deacetylase (MROD and EROD) activities, which reflect cytochrome P450 metabolism, were measured. R-state PolyHb displayed improved or intact activity in 3 out of 7 functions compared to unmodified Hb. T-state PolyHb displayed improved or intact activity in 4 out of 7 functions compared to unmodified Hb. Thus, PolyHbs, both in the R-state and T-state, are safer to use at a concentration of 10 mg/mL as compared to unmodified Hb in static culture liver-related applications.

Pilot scale production and characterization of next generation high molecular weight and tense quaternary state polymerized human hemoglobin

Polymerized human hemoglobin (PolyhHb) is being studied as a possible red blood cell (RBC) substitute for use in scenarios where blood is not available. While the oxygen (O2 ) carrying capacity of PolyhHb makes it appealing as an O2 therapeutic, the commercial PolyhHb PolyHeme® (Northfield Laboratories Inc.) was never approved for clinical use due to the presence of large quantities of low molecular weight (LMW) polymeric hemoglobin (Hb) species (<500 kDa), which have been shown to elicit vasoconstriction, systemic hypertension, and oxidative tissue injury in vivo. Previous bench-top scale studies in our lab demonstrated the ability to synthesize and purify PolyhHb using a two-stage tangential flow filtration purification process to remove almost all undesirable Hb species (>0.2 µm and <500 kDa) in the material, to create a product that should be safer for transfusion. Therefore, to enable future large animal studies and eventual human clinical trials, PolyhHb synthesis and purification processes need to be scaled up to the pilot scale. Hence in this study, we describe the pilot scale synthesis and purification of PolyhHb. Characterization of pilot scale PolyhHb showed that PolyhHb could be successfully produced to yield biophysical properties conducive for its use as an RBC substitute. Size exclusion high performance liquid chromatography showed that pilot scale PolyhHb yielded a high molecular weight Hb polymer containing a small percentage of LMW Hb species (<500 kDa). Additionally, the auto-oxidation rate of pilot scale PolyhHb was even lower than that of previous generations of PolyhHb. Taken together, these results demonstrate that PolyhHb has the ability to be seamlessly manufactured at the pilot scale to enable future large animal studies and clinical trials.

Intraosseous infusion of liposome-encapsulated hemoglobin (HbV) acutely prevents hemorrhagic anemia-induced lethal arrhythmias and its efficacy persists with preventing proarrhythmic side effects in subacute phase of severe hemodilution model

BACKGROUND

Artificial oxygen carriers (HbV) can treat hemorrhagic shock with lethal arrhythmias (VT/VF). No reports exist on subacute HbV's effects.

METHODS

Acute and subacute resuscitation effects with anti-arrhythmogenesis of HbV were studied in 85% blood exchange rat model (85%-Model). Lethal 85%-Model was created by bone marrow transfusion and femoral artery bleeding in 80 SD rats in HbV-administered group (HbV-group), washed erythrocyte-administered group (wRBC-group), and 5% albumin-administered group (ALB-group). Survival rates, anti-arrhythmic efficacy by optical mapping analysis (OMP) with electrophysiological stimulation (EPS) in Langendorff heart, cardiac autonomic activity by heart rate variability (HRV) and ventricular arrhythmias by 24-hour electrocardiogram telemetry monitoring (24h-ECG) in awake, and left ventricular function by echocardiography (LVEF) were measured.

RESULTS

All rats in HbV- and wRBC-groups survived for 4 weeks whereas no rats in ALB-group. HbV and wRBC acutely suppressed VT/VF in Langendorff heart through ameliorating action potential duration dispersion (APDd) analyzed by OMP with EPS. For subacute analysis, 50% blood exchange by 5% albumin was utilized (ALB-group 50). Subacute salutary effect on APDd and VT/VF inducibility was confirmed in HbV- and wRBC-groups. 24h-ECG showed that HbV and wRBC suppressed none-sustained VT (NSVT) and sympathetic component of HRV (LF/HF) with preserved LVEF (HbV-group, wRBC-group vs. ALB-group 50;NSVT numbers/days, 0.5±0.3, 0.4±0.3 vs. 3.9±1.2*; LF/HF, 1.1±0.2, 0.8±0.2 vs. 3.5±1.0*;LVEF, 84±5, 83±4, vs. 77±4%*; *p<0.05).

CONCLUSIONS

Collectively, HbV has sustained antiarrhythmic effect in subacute 85%-Model by ameliorating electrical remodeling and improving arrhythmogenic modifying factors (HRV and LVEF). These findings are useful in now continuing clinical trials of HbV.

Biophysical properties of tense quaternary state polymerized human hemoglobins bracketed between 500 kDa and 0.2 μm in size

Polymerized hemoglobin (Hb)-based oxygen carriers (HBOCs) are a scalable and cost-effective red blood cell (RBC) substitute. However, previous generations of commercial polymerized HBOCs elicited oxidative tissue injury in vivo due to the presence of low molecular weight polymeric Hb species (<500 kDa) and cell-free Hb (64 kDa). Polymerized human Hb (PolyhHb) locked in the tense quaternary state (T-state) exhibits great promise to meet clinical needs where past polymerized HBOCs failed. This work shows that separation of T-state PolyhHb via a two-stage tangential flow filtration (TFF) purification train such that the Hb polymers are bracketed between 500 kDa and 0.2 μm creates a uniform polymer size and largely eliminates the Hb species which elicit deleterious side effects in vivo. Biophysical characterization of these materials demonstrates their potential effectiveness as an RBC substitute and verifies the low percentage of low molecular weight Hb polymers and cell-free Hb. Size exclusion chromatography confirms that T-state PolyhHb can be consistently produced in a size range between 500 kDa and 0.2 μm. Furthermore, the average molecular weight of all PolyhHb species produced is one or two orders of magnitude larger than that of the commercial polymerized HBOCs Hemolink and Oxyglobin, respectively. Haptoglobin binding kinetics confirms that two-stage TFF processing of PolyhHb reliably removes cell-free Hb and low molecular weight polymeric Hb species. T-state PolyhHbs demonstrate lower auto-oxidation rates compared to unmodified Hb and prior generations of commercial polymerized HBOCs. These results demonstrate T-state PolyhHb's feasibility as a next-generation polymerized HBOC for potential use in transfusion medicine.

New Applications of HBOC-201: A 25-Year Review of the Literature

If not cured promptly, tissue ischemia and hypoxia can cause serious consequences or even threaten the life of the patient. Hemoglobin-based oxygen carrier-201 (HBOC-201), bovine hemoglobin polymerized by glutaraldehyde and stored in a modified Ringer's lactic acid solution, has been investigated as a blood substitute for clinical use. HBOC-201 was approved in South Africa in 2001 to treat patients with low hemoglobin (Hb) levels when red blood cells (RBCs) are contraindicated, rejected, or unavailable. By promoting oxygen diffusion and convective oxygen delivery, HBOC-201 may act as a direct oxygen donor and increase oxygen transfer between RBCs and between RBCs and tissues. Therefore, HBOC-201 is gradually finding applications in treating various ischemic and hypoxic diseases including traumatic hemorrhagic shock, hemolysis, myocardial infarction, cardiopulmonary bypass, perioperative period, organ transplantation, etc. However, side effects such as vasoconstriction and elevated methemoglobin caused by HBOC-201 are major concerns in clinical applications because Hbs are not encapsulated by cell membranes. This study summarizes preclinical and clinical studies of HBOC-201 applied in various clinical scenarios, outlines the relevant mechanisms, highlights potential side effects and solutions, and discusses the application prospects. Randomized trials with large samples need to be further studied to better validate the efficacy, safety, and tolerability of HBOC-201 to the extent where patient-specific treatment strategies would be developed for various clinical scenarios to improve clinical outcomes.

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.

Liposome-encapsulated hemoglobin (HbV) transfusion rescues rats undergoing progressive lethal 85% hemorrhage as a result of an anti-arrhythmogenic effect on the myocardium

Liposome-encapsulated hemoglobin vesicles (HbV) can serve as a blood substitute with oxygen-carrying capacity comparable to that of human blood and lethal hemorrhage is associated with lethal arrhythmias. To investigate the resuscitation effect of HbV on lethal hemorrhage and anti-arrhythmogenesis, we performed optical mapping analysis (OMP) and electrophysiological study (EPS) in graded blood exchange (85% blood loss) in the rat model. We also measured cardiac autonomic activity, as assessed by heart rate variability (HRV), and changes in plasma norepinephrine and left ventricle ejection fraction (LVEF) by echocardiography. Pathological study on Connexin43 was performed. A 5% albumin (ALB group), washed rat erythrocytes (wRBC group), and HbV (HbV group) were used as a resuscitation fluid. The survival effects over 24 hours were examined. All rats died in the ALB group, whereas almost all survived for 24-hours period in wRBC and HbV groups. OMP showed impaired action potential duration dispersion (APDd) in the ALB group, whereas normal APDs in HbV and wRBC groups. Lethal arrhythmias were induced by EPS in the ALB group, but not in wRBC and HbV groups. HRV indices, LVEF, Connexin43 were preserved in HbV and wRBC groups. Lethal hemorrhage causes lethal arrhythmias in the presence of impaired APDd. HbV acutely rescues lethal hemorrhage by preventing lethal arrhythmias and preserving arrhythmogenic factors.

Therapeutic Potential of Hemoglobin Derived from the Marine Worm Arenicola marina (M101): A Literature Review of a Breakthrough Innovation

Oxygen (O₂) is indispensable for aerobic respiration and cellular metabolism. In case of injury, reactive oxygen species are produced, causing oxidative stress, which triggers cell damaging chemical mediators leading to ischemic reperfusion injuries (IRI). Sufficient tissue oxygenation is necessary for optimal wound healing. In this context, several hemoglobin-based oxygen carriers have been developed and tested, especially as graft preservatives for transplant procedures. However, most of the commercially available O₂ carriers increase oxidative stress and show some adverse effects. Interestingly, the hemoglobin derived from the marine lugworm Arenicola marina (M101) has been presented as an efficient therapeutic O₂ carrier with potential anti-inflammatory, anti-bacterial, and antioxidant properties. Furthermore, it has demonstrated promise as a supplement to conventional organ preservatives by reducing IRI. This review summarizes the properties and various applications of M101. M101 is an innovative oxygen carrier with several beneficial therapeutic properties, and further research must be carried out to determine its efficacy in the management of different pathologies.

Oxygen Transport during Ex Situ Machine Perfusion of Donor Livers Using Red Blood Cells or Artificial Oxygen Carriers

Oxygenated ex situ machine perfusion of donor livers is an alternative for static cold preservation that can be performed at temperatures from 0 °C to 37 °C. Organ metabolism depends on oxygen to produce adenosine triphosphate and temperatures below 37 °C reduce the metabolic rate and oxygen requirements. The transport and delivery of oxygen in machine perfusion are key determinants in preserving organ viability and cellular function. Oxygen delivery is more challenging than carbon dioxide removal, and oxygenation of the perfusion fluid is temperature dependent. The maximal oxygen content of water-based solutions is inversely related to the temperature, while cellular oxygen demand correlates positively with temperature. Machine perfusion above 20 °C will therefore require an oxygen carrier to enable sufficient oxygen delivery to the liver. Human red blood cells are the most physiological oxygen carriers. Alternative artificial oxygen transporters are hemoglobin-based oxygen carriers, perfluorocarbons, and an extracellular oxygen carrier derived from a marine invertebrate. We describe the principles of oxygen transport, delivery, and consumption in machine perfusion for donor livers using different oxygen carrier-based perfusion solutions and we discuss the properties, advantages, and disadvantages of these carriers and their use.

Glutaraldehyde-Polymerized Hemoglobin: In Search of Improved Performance as Oxygen Carrier in Hemorrhage Models

Hemoglobin- (Hb-) based oxygen carriers (HBOC) have for several decades been explored for treatment of hemorrhage. In our previous top-up tests, HBOC with lower in vitro prooxidant reactivity (incorporating a peroxidase or serum albumin to this end) showed a measurable but small improvement of oxidative stress-related parameters. Here, such HBOCs are tested in a hemorrhage set-up; ovine hemoglobin is also tested for the first time in such a setting, based on in vitro data showing its improved performance versus bovine Hb against oxidative and nitrosative stress agents. Indeed, ovine Hb performs better than bovine Hb in terms of survival rates, arterial tension, immunology, and histology. On the other hand, unlike in the top-up models, where the nonheme peroxidase rubrerythrin as well as bovine serum albumin copolymerized with Hb were shown to improve the performance of HBOC, in the present hemorrhage models rubrerythrin fails dramatically as HBOC ingredient (with a distinct immunological reaction), whereas serum albumin appears not feasible if its source is a different species (i.e., bovine serum albumin fares distinctly worse than rat serum albumin, in HBOC transfusions in rats). An effect of the matrix in which the HBOCs are dissolved (PBS versus gelofusine versus plasma) is noted.

Comprehensive characterization of tense and relaxed quaternary state glutaraldehyde polymerized bovine hemoglobin as a function of cross-link density

Previously, our lab developed high molecular weight (MW) tense (T) quaternary state glutaraldehyde polymerized bovine hemoglobins (PolybHbs) that exhibited reduced vasoactivity in several small animal models. In this study, we prepared PolybHb in the T and relaxed (R) quaternary state with ultrahigh MW (>500 kDa) with varying cross-link densities, and investigated the effect of MW on key biophysical properties (i.e., O₂ affinity, cooperativity (Hill) coefficient, hydrodynamic diameter, polydispersity, polymer composition, viscosity, gaseous ligand-binding kinetics, auto-oxidation, and haptoglobin [Hp]-binding kinetics). To further optimize current PolybHb synthesis and purification protocols, we performed a comprehensive meta-data analysis to evaluate correlations between procedural parameters (i.e., cross-linker:bovine hemoglobin (bHb) molar ratio, gas-liquid exchange time, temperature during sodium dithionite addition, and number of diafiltration cycles) and the biophysical properties of both T- and R-state PolybHbs. Our results showed that, the duration of the fast-step auto-oxidation phase of R-state PolybHb increased with decreasing glutaraldehyde:bHb molar ratio. Additionally, T-state PolybHbs exhibited significantly higher bimolecular rate constants for binding to Hp and unimolecular O₂ offloading rate constants compared to R-state PolybHbs. The methemoglobin (metHb) level in the final product was insensitive to the molar ratio of glutaraldehyde to bHb for all PolybHbs. During tangential flow filtration processing of the final product, 14 diafiltration cycles was found to yield the lowest metHb level.

A case study of 10 patients administered HBOC-201 in high doses over a prolonged period: outcomes during severe anemia when transfusion is not an option

BACKGROUND

Hemoglobin-Based Oxygen Carriers (HBOCs) can act as an "oxygen bridge" in acute severe anemia when transfusion is indicated, but not possible. We present data on 10 Expanded Access (EA) patients treated with high cumulative doses of Hemopure (HBOC-201), to assess the ability of HBOC-201 to safely treat life threatening anemia in situations where high volumes of product were administered over an extended period of time.

STUDY DESIGN AND METHODS

Inclusion in this study required that the patient receive at least 10 units of HBOC-201 between 2014 and 2017 under the FDA-sanctioned EA program. Depending on a patient's geographical location, treatment with HBOC-201 was obtained through either a single patient emergency Investigational New Drug (IND) application, or an intermediate size population IND. Of the 41 patients who were treated during this period, 10 patients received 10 or more units of the product. Data were obtained from medical records.

RESULTS

Treatments with HBOC-201 started within 24 hours of signing consent and were administered at an average rate of 1.99 (SD 0.17) units per day over a mean of 8.2 days (SD 2.9), during which patients received on average 16.2 units (SD 5.7 units) of HBOC-201. The median pre-treatment nadir corpuscular hemoglobin (Hb) concentration was 3.3 (SD 0.9) g/dL and post-treatment Hemoglobin was 7.3 (SD 1.7) g/dL. Common side effects included methemoglobinemia, gastrointestinal symptoms, and hypertension. However, no product-related serious adverse events (SAEs) were noted. All patients survived.

CONCLUSIONS

Administration of HBOC-201 over an extended period is a feasible and safe oxygen bridge for severely anemic patients who cannot be transfused with RBC.

Selective aortic arch perfusion with fresh whole blood or HBOC-201 reverses hemorrhage-induced traumatic cardiac arrest in a lethal model of noncompressible torso hemorrhage

BACKGROUND

Hemorrhage-induced traumatic cardiac arrest (HiTCA) has a dismal survival rate. Previous studies demonstrated selective aortic arch perfusion (SAAP) with fresh whole blood (FWB) improved the rate of return of spontaneous circulation (ROSC) after HiTCA, compared with resuscitative endovascular balloon occlusion of the aorta and cardiopulmonary resuscitation (CPR). Hemoglobin-based oxygen carriers, such as hemoglobin-based oxygen carrier (HBOC)-201, may alleviate the logistical constraints of using FWB in a prehospital setting. It is unknown whether SAAP with HBOC-201 is equivalent in efficacy to FWB, whether conversion from SAAP to extracorporeal life support (ECLS) is feasible, and whether physiologic derangement post-SAAP therapy is reversible.

METHODS

Twenty-six swine (79 ± 4 kg) were anesthetized and underwent HiTCA which was induced via liver injury and controlled hemorrhage. Following arrest, swine were randomly allocated to resuscitation using SAAP with FWB (n = 12) or HBOC-201 (n = 14). After SAAP was initiated, animals were monitored for a 20-minute prehospital period prior to a 40-minute damage control surgery and resuscitation phase, followed by 260 minutes of critical care. Primary outcomes included rate of ROSC, survival, conversion to ECLS, and correction of physiology.

RESULTS

Baseline physiologic measurements were similar between groups. ROSC was achieved in 100% of the FWB animals and 86% of the HBOC-201 animals (p = 0.483). Survival (t = 320 minutes) was 92% (11/12) in the FWB group and 67% (8/12) in the HBOC-201 group (p = 0.120). Conversion to ECLS was successful in 100% of both groups. Lactate peaked at 80 minutes in both groups, and significantly improved by the end of the experiment in the HBOC-201 group (p = 0.001) but not in the FWB group (p = 0.104). There was no significant difference in peak or end lactate between groups.

CONCLUSION

Selective aortic arch perfusion is effective in eliciting ROSC after HiTCA in a swine model, using either FWB or HBOC-201. Transition from SAAP to ECLS after definitive hemorrhage control is feasible, resulting in high overall survival and improvement in lactic acidosis over the study period.

Next-generation polymerized human hemoglobins in hepatic bioreactor simulations

Hepatic hollow fiber (HF) bioreactors can be used to provide temporary support to patients experiencing liver failure. Before being connected to the patient's circulation, cells in the bioreactor must be exposed to a range of physiological O₂ concentrations as observed in the liver sinusoid to ensure proper performance. This zonation in cellular oxygenation promotes differences in hepatocyte phenotype and may better approximate the performance of a real liver within the bioreactor. Polymerized human hemoglobin (PolyhHb) locked in the tense quaternary state (T-state) has the potential to both supply and regulate O₂ transport to cultured hepatocytes in the bioreactor due to its low O₂ affinity. In this study, T-state PolyhHb production and purification processes were optimized to minimize the concentration of low-molecular-weight PolyhHb species in solution. Deconvolution of size-exclusion chromatography spectra was performed to calculate the distribution of polymeric Hb species in the final product. Fluid flow and mass transport within a single fiber of a hepatic HF bioreactor was computationally modeled with finite element methods to simulate the effects of employing T-state PolyhHb to facilitate O₂ transport in a hepatic bioreactor system. Optimal bioreactor performance was defined as having a combined hypoxic and hyperoxic volume fraction in the extracapillary space of less than 0.05 where multiple zones were observed. The Damköhler number and Sherwood number had strong inverse relationships at each cell density and fiber thickness combination. These results suggest that targeting a specific Damköhler number may be beneficial for optimal hepatic HF bioreactor operation.

Issues in the development of hemoglobin based oxygen carriers

Hemoglobin based oxygen carriers (HBOCs) have been developed as alternative oxygen transporting formulations for the acute treatment of anemia and ischemia. Efficacy has been demonstrated in a variety of preclinical models and selected human patients; however, a higher overall incidence of mortality and myocardial infarction in those dosed with HBOCs in later stage clinical trials has prevented widespread regulatory approval. Diagnosis of myocardial infarction is confounded by the fact that HBOCs interfere with troponin assays, as well as other clinical chemistry measurements. Analysis of data pertaining to potential toxicity mechanisms suggests that coronary vasoconstriction is an unlikely contributor, but promotion of intravascular thrombosis may occur by several mechanisms. In addition, fluid and anemia management in patients infused with HBOCs has been suboptimal. Elucidation of potential toxicity mechanisms, refinement of use protocols, and definition of improved patient inclusion/exclusion criteria remain active areas of inquiry in understanding the best manner in which to utilize HBOCs.

Treatment of acute leukaemia in adult Jehovah's Witnesses

Since Jehovah's Witness (JW) patients diagnosed with leukaemia refuse blood transfusions, they are often denied intensive chemotherapy for fear they could not survive myeloablation without blood transfusion support. Treatment of JW patients with acute leukaemia is challenging and carries a higher morbidity and mortality; however, the refusal of blood products should not be an absolute contraindication to offer multiple treatment modalities including haematopoietic stem cell transplantation. In this review we discuss their optimal management and describe alternative modalities to blood transfusions to provide sufficient oxygenation and prevent bleeding.

The need for dried plasma - a national issue

Recent studies have demonstrated that early transfusion of plasma or RBCs improves survival in patients with severe trauma and hemorrhagic shock. Time to initiate transfusion is the critical factor. It is essential that transfusion begin in the prehospital environment when transport times are longer than approximately 15 to 20 minutes. Unfortunately, logistic constraints severely limit the use of blood products in the prehospital setting, especially in military, remote civilian, and mass disaster circumstances, where the need can be most acute. US military requirements for logistically supportable blood products are projected to increase dramatically in future conflicts. Although dried plasma products have been available and safely used in a number of countries for over 20 years, there is no dried plasma product commercially available in the United States. A US Food and Drug Administration-approved dried plasma is urgently needed. Considering the US military, disaster preparedness, and remote civilian trauma perspectives, this is an urgent national health care issue.

Combination therapy using fibrinogen γ-chain peptide-coated, ADP-encapsulated liposomes and hemoglobin vesicles for trauma-induced massive hemorrhage in thrombocytopenic rabbits

BACKGROUND

We previously developed substitutes for red blood cells (RBCs) and platelets (PLTs) for transfusion. These substitutes included hemoglobin vesicles (HbVs) and fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV, H12)-coated, adenosine diphosphate (ADP)-encapsulated liposomes [H12-(ADP)-liposomes]. Here, we examined the efficacy of combination therapy using these substitutes instead of RBC and PLT transfusion in a rabbit model with trauma-induced massive hemorrhage with coagulopathy.

STUDY DESIGN AND METHODS

Thrombocytopenia (PLT count approximately 40,000/μL) was induced in rabbits by repeated blood withdrawal and isovolemic transfusion with autologous RBCs. Thereafter, lethal hemorrhage was induced in rabbits by noncompressible penetrating liver injury. Subsequently, H12-(ADP)-liposomes with platelet-poor plasma (PPP), platelet-rich plasma (PRP), or PPP alone were administered to stop bleeding. Once achieving hemostasis, HbVs, allogenic RBCs, or 5% albumin were transfused into rabbits to rescue them from fatal anemia following massive hemorrhage.

RESULTS

Administration of H12-(ADP)-liposomes/PPP as well as PRP (but not PPP) effectively stopped liver bleeding (100% hemostasis). The subsequent administration with HbVs as well as RBCs after hemostasis markedly rescued rabbits from fatal anemia (75% and 70% survivals for 24 hr, respectively). In contrast, 5% albumin administration rescued none of the rabbits.

CONCLUSION

Combination therapy with H12-(ADP)-liposomes and HbVs may be effective for damage control resuscitation of trauma-induced massive hemorrhage.

Haemoglobin-based oxygen carriers and myocardial infarction

The incidence of investigator diagnosed myocardial infarction (MI) is greater in patients treated with haemoglobin-based oxygen carriers (HBOCs) than controls. Clinical trials and literature pertaining to possible HBOC toxicity mechanisms have been analyzed in order to identify possible reasons for this imbalance. MI diagnosis is hampered by potential interference of troponin assays by haemoglobin, haemolysis and bilirubin. Nevertheless, insofar as the reported incidence correlates with actual occurrence, there is a positive relationship between MI and HBOC dose and size. Preclinical and clinical data suggest that direct cardiac toxicity and coronary vasoconstriction are unlikely. More probable are detrimental intravascular interactions between HBOCs and components of the coagulation cascade, particularly dysfunctional endothelium. Elucidation of mechanisms is impeded by a lack of clinical data. Measurement of relevant biomarkers would be extremely useful in this regard and in improving patient selection criteria. Conduct of clinical trials in carefully selected patient populations after the development of improved protocols for MI diagnosis, along with concomitant biomarker data collection, is recommended.

Preventing acute kidney injury during transplantation: the application of novel oxygen carriers

INTRODUCTION

Delayed graft function (DGF) has a significant impact on kidney transplantation outcome. One of the underlying pivotal mechanisms is organ preservation and associated hypothermia and biochemical alteration.

AREAS COVERED

This paper focuses on organ preservation and its clinical consequences and describes 1. A comprehensive presentation of the pathophysiological mechanism involved in delayed graft function development; 2. The impact on endothelial cells and microvasculature integrity and the consequences on transplanted organ outcome; 3. The reassessment of dynamic organ preservation motivated by the growing use of extended criteria donors and the interest in the potential of normothermia; 4. The role of oxygenation during dynamic preservation; and 5. Novel oxygen carriers and their proof of concept in transplantation, among which M101 (HEMO₂life®) is currently the most extensively investigated.

EXPERT OPINION

Metabolic disturbances and imbalance of oxygen supply during preservation highlight the importance of providing oxygen. Normothermia, permitted by recent advances in machine perfusion technology, appears to be the leading edge of preservation technology. Several oxygen transporters are compatible with normothermia; however, only M101 also demonstrates compatibility with standard hypothermic preservation.

Increasing the stability of Lumbricus terrestris erythrocruorin via poly(acrylic acid) conjugation

Since donated red blood cells must be constantly refrigerated, they are often unavailable in remote areas and battlefields. The goal of this study was to synthesize a highly stable blood substitute that does not require refrigeration. Specifically, the extracellular haemoglobin (a.k.a. erythrocruorin, Ec) of the earthworm Lumbricus terrestris erythrocruororin (LtEc) was cross-linked with poly(acrylic acid) (PAA) and ethylene diamine (EDA). PAGE analysis of the LtEc nanoparticles reveals cross-linking between subunits, while dynamic light scattering and scanning electron microscopy show that cross-linking significantly increases the size of the LtEc nanoparticles (164 ± 13.9 nm). Cross-linking also significantly increased the thermal stability of the LtEc nanoparticles by 10 °C (Tm = 72 ± 0.84 °C) relative to native LtEc (Tm = 62 ± 0.6 °C). In addition, while native LtEc rapidly dissociates at pH 9, the LtEc nanoparticles resist subunit dissociation up to pH 10. The oxygen affinity of the LtEc nanoparticles (P50 = 6.85 ± 0.13 mm Hg) is much higher than native LtEc (P50 = 26.67 ± 0.4 mm Hg), but the cooperativity (n = 2.43 ± 0.12) is not affected. Altogether, these results show that cross-linking LtEc with PAA and EDA provides a potential blood substitute with increased stability and oxygen affinity.

The quaternary state of polymerized human hemoglobin regulates oxygenation of breast cancer solid tumors: A theoretical and experimental study

A major constraint in the treatment of cancer is inadequate oxygenation of the tumor mass, which can reduce chemotherapeutic efficacy. We hypothesize that polymerized human hemoglobin (PolyhHb) can be transfused into the systemic circulation to increase solid tumor oxygenation, and improve chemotherapeutic outcomes. By locking PolyhHb in the relaxed (R) quaternary state, oxygen (O2) offloading at low O2 tensions (<20 mm Hg) may be increased, while O2 offloading at high O2 tensions (>20 mm Hg) is facilitated with tense (T) state PolyhHb. Therefore, R-state PolyhHb may deliver significantly more O2 to hypoxic tissues. Biophysical parameters of T and R-state PolyhHb were used to populate a modified Krogh tissue cylinder model to assess O2 transport in a tumor. In general, we found that increasing the volume of transfused PolyhHb decreased the apparent viscosity of blood in the arteriole. In addition, we found that PolyhHb transfusion decreased the wall shear stress at large arteriole diameters (>20 μm), but increased wall shear stress for small arteriole diameters (<10 μm). Therefore, transfusion of PolyhHb may lead to elevated O2 delivery at low pO2. In addition, transfusion of R-state PolyhHb may be more effective than T-state PolyhHb for O2 delivery at similar transfusion volumes. Reduction in the apparent viscosity resulting from PolyhHb transfusion may result in significant changes in flow distributions throughout the tumor microcirculatory network. The difference in wall shear stress implies that PolyhHb may have a more significant effect in capillary beds through mechano-transduction. Periodic top-load transfusions of PolyhHb into mice bearing breast tumors confirmed the oxygenation potential of both PolyhHbs via reduced hypoxic volume, vascular density, tumor growth, and increased expression of hypoxia inducible genes. Tissue section analysis demonstrated primary PolyhHb clearance occurred in the liver and spleen indicating a minimal risk for renal damage.

In vivo evaluation of hemerythrin-based oxygen carriers: Similarities with hemoglobin-based counterparts

We have previously proposed the annelid-derived protein, hemerythrin, as a viable replacement for hemoglobin in the synthesis of semi-synthetic oxygen carriers ("blood substitutes"). Here, we report the first in vivo tests for potential hemerythrin-based oxygen carriers (HrBOC), using a battery of experiments involving Wistar rats and previously tested on a series of hemoglobin-based oxygen carrier candidates (HBOC). At the concentrations tested, hemerythrin appears to behave similarly to hemoglobin - including, importantly, immunological effects. The antioxidant strategies based on albumin as well as based on rubrerythrin appear to offer observable physiological advantages.

Hemoglobin-Based Oxygen Carrier Rescues Double-Transplant Patient From Life-Threatening Anemia

This case describes a 46-year-old male recipient of a kidney-pancreas transplant who is Jehovah's Witness. Early in the postoperative period, he was found to have splenic vein thrombosis requiring heparin infusion. Two days later, he developed severe symptomatic anemia (hemoglobin <6 g/dL). Standard medical therapy for bloodless surgical patients with severe anemia was instituted. Nevertheless, the patient's hemoglobin concentration continued to decline to critical levels (2 g/dL). Because he was Jehovah's Witness, transfusion of allogeneic blood products was not an option, prompting use of a hemoglobin-based oxygen carrier (HBOC). After approval by the U.S. Food and Drug Administration and the local institutional review board, 12 U of HBOC-201 were transfused over a period of 8 days. Two weeks later, the patient's hemoglobin levels had increased to 6.8 g/dL. The patient's overall clinical condition improved, and he was discharged home. This case describes the first use of HBOC transfusion in a double solid organ transplant patient. HBOC may represent a viable option in patients with severe symptomatic anemia when allogeneic blood transfusion is not an option.

Management of the Jehovah's Witness in Obstetrics and Gynecology: A Comprehensive Medical, Ethical, and Legal Approach

IMPORTANCE

Obstetricians and gynecologists frequently deal with hemorrhage so they should be familiar with management of patients who refuse blood transfusion. Although there are some reports in the literature about management of Jehovah's Witness patients in obstetrics and gynecology, most of them are case reports, and a comprehensive review about these patients including ethicolegal perspective is lacking.

OBJECTIVE

This review outlines the medical, ethical, and legal implications of management of Jehovah's Witness patients in obstetrical and gynecological settings.

EVIDENCE ACQUISITION

A search of published literature using PubMed, Ovid Medline, EMBASE, and Cochrane databases was conducted about physiology of oxygen delivery and response to tissue hypoxia, mortality rates at certain hemoglobin levels, medical management options for anemic patients who refuse blood transfusion, and ethical/legal considerations in Jehovah's Witness patients.

RESULTS

Early diagnosis of anemia and immediate initiation of therapy are essential in patients who refuse blood transfusion. Medical management options include iron supplementation and erythropoietin. There are also some promising therapies that are in development such as antihepcidin antibodies and hemoglobin-based oxygen carriers. Options to decrease blood loss include antifibrinolytics, desmopressin, recombinant factor VII, and factor concentrates. When surgery is the only option, every effort should be made to pursue minimally invasive approaches.

CONCLUSION AND RELEVANCE

All obstetricians and gynecologists should be familiar with alternatives and "less invasive" options for patients who refuse blood transfusions.

Prolonging the shelf life of Lumbricus terrestris erythrocruorin for use as a novel blood substitute

Limitations associated with the storage of red blood cells have motivated the development of novel blood substitutes that are able to withstand long-term storage at elevated temperatures. The hemoglobin of the earthworm Lumbricus terrestris (LtEc) is an attractive blood substitute candidate, since it is resistant to oxidation and aggregation during storage. Several factors were investigated to optimize the thermal and oxidative stability of LtEc during storage, including pH, antioxidant supplements, and deoxygenation. A strategy for the reduction of fully oxidized LtEc with antioxidants was also developed. Overall, LtEc was shown to have the highest thermal stability in Ringer's Modified Lactate solution with 10 mM HEPES at pH 7.0. Deoxygenation of the LtEc was also shown to significantly reduce oxidation of the ferrous heme iron (e.g., %Fe²⁺after 7 d at 37 °C = 75.7%). However, even in cases where oxidation does occur, the addition of 1.8 mM ascorbic acid (AA) was found to reduce 98.3% of the oxidized LtEc (37 μM heme). Most importantly, the oxygen transport properties of LtEc were unaffected by storage at high temperatures or oxidation followed by reduction with AA. These results show that LtEc can be stored at high temperatures (37 °C) without any significant loss of function.

Cardiac function during resuscitation from hemorrhagic shock with polymerized bovine hemoglobin-based oxygen therapeutic

Hemorrhage impairs myocardial contractile function and decreases oxygen delivery. This study investigates how polymerized bovine hemoglobin (PolyHb) solutions affect cardiac function after resuscitation from hemorrhagic shock (HS). Hamsters were hemorrhaged and resuscitated with PolyHb at 8.5 g/dL and 11.5 g/dL. Left ventricle (LV) function was assessed during shock and resuscitation using a miniaturize conductance catheter. PolyHb resuscitation had no beneficial effects in cardiac function; it increased cardiac afterload and systemic vascular resistance (SVR) of 46 and 116% for 8.5 and 11.5 g/dL, respectively. Study findings indicate that preclinical evaluation of cardiac function is essential to develop safe and efficacious alternatives to blood transfusion.

Machine Perfusion of Porcine Livers with Oxygen-Carrying Solution Results in Reprogramming of Dynamic Inflammation Networks

Background:Ex vivo machine perfusion (MP) can better preserve organs for transplantation. We have recently reported on the first application of an MP protocol in which liver allografts were fully oxygenated, under dual pressures and subnormothermic conditions, with a new hemoglobin-based oxygen carrier (HBOC) solution specifically developed for ex vivo utilization. In those studies, MP improved organ function post-operatively and reduced inflammation in porcine livers. Herein, we sought to refine our knowledge regarding the impact of MP by defining dynamic networks of inflammation in both tissue and perfusate.

Methods: Porcine liver allografts were preserved either with MP (n = 6) or with cold static preservation (CSP; n = 6), then transplanted orthotopically after 9 h of preservation. Fourteen inflammatory mediators were measured in both tissue and perfusate during liver preservation at multiple time points, and analyzed using Dynamic Bayesian Network (DyBN) inference to define feedback interactions, as well as Dynamic Network Analysis (DyNA) to define the time-dependent development of inflammation networks.

Results: Network analyses of tissue and perfusate suggested an NLRP3 inflammasome-regulated response in both treatment groups, driven by the pro-inflammatory cytokine interleukin (IL)-18 and the anti-inflammatory mediator IL-1 receptor antagonist (IL-1RA). Both DyBN and DyNA suggested a reduced role of IL-18 and increased role of IL-1RA with MP, along with increased liver damage with CSP. DyNA also suggested divergent progression of responses over the 9 h preservation time, with CSP leading to a stable pattern of IL-18-induced liver damage and MP leading to a resolution of the pro-inflammatory response. These results were consistent with prior clinical, biochemical, and histological findings after liver transplantation.

Conclusion: Our results suggest that analysis of dynamic inflammation networks in the setting of liver preservation may identify novel diagnostic and therapeutic modalities.

Anemia in Intensive Care: A Review of Current Concepts

Anemia in patients admitted to an intensive care unit is common and affects almost all critically ill patients. The intensivist is faced with the challenge of treating multifactorial etiologies, mainly bleeding and blood loss due to phlebotomy and decreased erythropoiesis. Red cell transfusion, the most common treatment for anemia, comes with associated risks, which may further reduce the chance of survival of these patients. The best evidence suggests the practice of restrictive RBC transfusion (transfusion at Hb<7 g/dl). In this article, the etiopathogenesis of the anemia in critically ill is reviewed, and current opinion on the pros and cons of various management strategies are discussed with emphasize on restrictive transfusion policy.

Past, present and forecast of transfusion medicine: What has changed and what is expected to change?

Blood transfusion is the second most used medical procedures in health care systems worldwide. Over the last few decades, significant changes have been evolved in transfusion medicine practices. These changes were mainly needed to increase safety, efficacy, and availability of blood products as well as reduce recipients' unnecessary exposure to allogeneic blood. Blood products collection, processing, and storage as well as transfusion practices throughout all patient populations were the main stream of these changes. Health care systems across the world have adopted some or most of these changes to reduce transfusion risks, to improve overall patients' outcome, and to reduce health care costs. In this article, we are going to present and discuss some of these recent modifications and their impact on patients' safety.

Comparative In Vivo Effects of Hemoglobin-Based Oxygen Carriers (HBOC) with Varying Prooxidant and Physiological Reactivity

A series of hemoglobin-based oxygen carrier candidates (HBOC), previously noted for their differences in prooxidative and physiological reactivity, were compared in terms of the negative effects displayed upon injection in Wistar rats. At the concentrations tested, antioxidant strategies based on albumin as well as based on rubrerythrin appear to offer observable physiological advantages.

Hemoglobin-Based Oxygen Carrier for Traumatic Hemorrhagic Shock Treatment in a Jehovah's Witness

Introduction:

Treatment of severe hemorrhagic shock due to acute blood loss from traumatic injuries in a Jehovah’s witness (JW) trauma patient is very challenging since hemostatic blood product resuscitation is limited by refusal of the transfusion of allogeneic blood products.

Case Presentation:

We describe a multifaceted approach to the clinical care of a severely anemic JW trauma patient including the early administration of a bovine hemoglobin-based oxygen carrier (HBOC) as a bridge to resolution of critical anemia (nadir hemoglobin 3.9 g/dL). Hemoglobin-based oxygen carrier infusions were used to supplement oxygen delivery until endogenous erythropoiesis could restore adequate red blood cell mass. Subsequent endogenous bone marrow recovery was supported by early administration of high-dose erythropoiesis-stimulating agents and iron supplementation.

Conclusions:

Early HBOC administration can be used in the treatment of severe hemorrhagic shock in trauma patients who refuse allogeneic blood.

Liver preservation with machine perfusion and a newly developed cell-free oxygen carrier solution under subnormothermic conditions

We describe a new preservation modality combining machine perfusion (MP) at subnormothermic conditions(21 °C) with a new hemoglobin-based oxygen carrier (HBOC) solution. MP (n=6) was compared to cold static preservation (CSP; n=6) in porcine orthotopic liver transplants after 9 h of cold ischemia and 5-day follow-up. Recipients' peripheral blood, serial liver biopsies, preservation solutions and bile specimens were collected before, during and after liver preservation. Clinical laboratorial and histological analyses were performed in addition to mitochondrial functional assays, transcriptomic, metabolomic and inflammatory inflammatory mediator analyses. Compared with CSP, MP animals had: (1) significantly higher survival (100%vs. 33%; p<0.05); (2) superior graft function (p<0.05);(3) eight times higher hepatic O2 delivery than O2 consumption (0.78 mL O2/g/h vs. 0.096 mL O2/g/h) during MP; and (4) significantly greater bile production (MP=378.5 ± 179.7; CS=151.6 ± 116.85). MP downregulated interferon (IFN)-α and IFN-γ in liver tissue. MP allografts cleared lactate, produced urea, sustained gluconeogenesis and produced hydrophilic bile after reperfusion. Enhanced oxygenation under subnormothermic conditions triggers regenerative and cell protective responses resulting in improved allograft function. MP at 21 °C with the HBOC solution significantly improves liver preservation compared to CSP.

A novel nanobiotherapeutic poly-[hemoglobin-superoxide dismutase-catalase-carbonic anhydrase] with no cardiac toxicity for the resuscitation of a rat model with 90 minutes of sustained severe hemorrhagic shock with loss of 2/3 blood volume

We crosslink hemoglobin (Hb), superoxide dismutase (SOD), catalase (CAT), and carbonic anhydrase (CA) to form a soluble polyHb-SOD-CAT-CA nanobiotechnological complex. The obtained product is a soluble complex with three enhanced red blood cell (RBC) functions and without blood group antigens. In the present study, 2/3 of blood volume was removed to result in 90-min hemorrhagic shock at mean arterial blood pressure (MAP) of 30 mmHg. This was followed by the reinfusion of different resuscitation fluids, then followed for another 60 min. PolyHb-SOD-CAT-CA maintained the MAP at 87.5 ± 5 mmHg as compared with 3 volumes of lactated Ringer's solution, 43.3 ± 2.8 mmHg; blood, 91.3 ± 3.6 mmHg; polyHb-SOD-CAT, 86.0 ± 4.6 mmHg; poly stroma-free hemolysate (polySFHb), 85.0 ± 2.5 mmHg; and polyHb, 82.6 ± 3.5 mmHg. PolyHb-SOD-CAT-CA was superior to the blood and other fluids based on the following criteria. PolyHb-SOD-CAT-CA reduced tissue pCO2 from 98 ± 4.5 mmHg to 68.6 ± 3 mmHg. This was significantly (p < 0.05) more effective than lactated Ringer's solution (98 ± 4.5 mmHg), polyHb (90.1 ± 4.0 mmHg), polyHb-SOD-CAT (90.9 ± 1.4 mmHg), blood (79.1 ± 4.7 mmHg), and polySFHb (77 ± 5 mmHg). PolyHb-SOD-CAT-CA reduced the elevated ST level to 21.7 ± 6.7% and is significantly (< 0.05) better than polyHb (57.7 ± 8.7%), blood (39.1 ± 1.5%), polySFHb (38.3% ± 2.1%), polyHb-SOD-CAT (27.8 ± 5.6%), and lactated Ringer's solution (106 ± 3.1%). The plasma cardiac troponin T (cTnT) level of polyHb-SOD-CAT-CA group was significantly (P < 0.05) lower than that of all the other groups. PolyHb-SOD-CAT-CA reduced plasma lactate level from 18 ± 2.3 mM/L to 6.9 ± 0.3 mM/L. It was significantly more effective (P < 0.05) than lactated Ringer's solution (12.4 ± 0.6 mM/L), polyHb (9.6 ± 0.7 mM/L), blood (8.1 ± 0.2 mM/L), polySFHb (8.4 ± 0.1 mM/L), and polyHb-SOD-CAT (7.6 ± 0.3 mM/L). PolyHb-SOD-CAT-CA can be stored for 320 days at room temperature. Lyophilized poly-Hb-SOD-CAT-CA can be heat pasteurized at 68F for 2 h. This can be important if there is a need to inactivate human immunodeficiency virus, Ebola virus, and other infectious organisms.