An extracellular oxygen carrier during prolonged pulmonary preservation improves post-transplant lung function

How Nitric Oxide Hindered the Search for Hemoglobin-Based Oxygen Carriers as Human Blood Substitutes

The search for a clinically affordable substitute of human blood for transfusion is still an unmet need of modern society. More than 50 years of research on acellular hemoglobin (Hb)-based oxygen carriers (HBOC) have not yet produced a single formulation able to carry oxygen to hemorrhage-challenged tissues without compromising the body's functions. Of the several bottlenecks encountered, the high reactivity of acellular Hb with circulating nitric oxide (NO) is particularly arduous to overcome because of the NO-scavenging effect, which causes life-threatening side effects as vasoconstriction, inflammation, coagulopathies, and redox imbalance. The purpose of this manuscript is not to add a review of candidate HBOC formulations but to focus on the biochemical and physiological events that underly NO scavenging by acellular Hb. To this purpose, we examine the differential chemistry of the reaction of NO with erythrocyte and acellular Hb, the NO signaling paths in physiological and HBOC-challenged situations, and the protein engineering tools that are predicted to modulate the NO-scavenging effect. A better understanding of two mechanisms linked to the NO reactivity of acellular Hb, the nitrosylated Hb and the nitrite reductase hypotheses, may become essential to focus HBOC research toward clinical targets.

EFFECTS OF M101-AN EXTRACELLULAR HEMOGLOBIN-APPLIED DURING CARDIOPULMONARY RESUSCITATION: AN EXPERIMENTAL RODENT STUDY

ABSTRACT

During and immediately after cardiac arrest, cerebral oxygen delivery is impaired mainly by microthrombi and cerebral vasoconstriction. This may narrow capillaries so much that it might impede the flow of red blood cells and thus oxygen transport. The aim of this proof-of-concept study was to evaluate the effect of M101, an extracellular hemoglobin-based oxygen carrier (Hemarina SA, Morlaix, France) derived from Arenicola marina , applied during cardiac arrest in a rodent model, on markers of brain inflammation, brain damage, and regional cerebral oxygen saturation. Twenty-seven Wistar rats subjected to 6 min of asystolic cardiac arrest were infused M101 (300 mg/kg) or placebo (NaCl 0.9%) concomitantly with start of cardiopulmonary resuscitation. Brain oxygenation and five biomarkers of inflammation and brain damage (from blood, cerebrospinal fluid, and homogenates from four brain regions) were measured 8 h after return of spontaneous circulation. In these 21 different measurements, M101-treated animals were not significantly different from controls except for phospho-tau only in single cerebellum regions ( P = 0.048; ANOVA of all brain regions: P = 0.004). Arterial blood pressure increased significantly only at 4 to 8 min after return of spontaneous circulation ( P < 0.001) and acidosis decreased ( P = 0.009). While M101 applied during cardiac arrest did not significantly change inflammation or brain oxygenation, the data suggest cerebral damage reduction due to hypoxic brain injury, measured by phospho-tau. Global burden of ischemia appeared reduced because acidosis was less severe. Whether postcardiac arrest infusion of M101 improves brain oxygenation is unknown and needs to be investigated.

Evaluation of 10°C as the optimal storage temperature for aspiration-injured donor lungs in a large animal transplant model

BACKGROUND

Our recent work has challenged 4°C as an optimal lung preservation temperature by showing storage at 10°C to allow for the extension of preservation periods. Despite these findings, the impact of 10°C storage has not been evaluated in the setting of injured donor lungs.

METHODS

Aspiration injury was created through bronchoscopic delivery of gastric juice (pH: 1.8). Injured donor lungs (n = 5/group) were then procured and blindly randomized to storage at 4°C (on ice) or at 10°C (in a thermoelectric cooler) for 12 hours. A third group included immediate transplantation. A left lung transplant was performed thereafter followed by 4 hours of graft evaluation.

RESULTS

After transplantation, lungs stored at 10°C showed significantly better oxygenation when compared to 4°C group (343 ± 43 mm Hg vs 128 ± 76 mm Hg, p = 0.03). Active metabolism occurred during the 12 hours storage period at 10°C, producing cytoprotective metabolites within the graft. When compared to lungs undergoing immediate transplant, lungs preserved at 10°C tended to have lower peak airway pressures (p = 0.15) and higher dynamic lung compliances (p = 0.09). Circulating cell-free mitochondrial DNA within the recipient plasma was significantly lower for lungs stored at 10°C in comparison to those underwent immediate transplant (p = 0.048), alongside a tendency of lower levels of tissue apoptotic cell death (p = 0.075).

CONCLUSIONS

We demonstrate 10°C as a potentially superior storage temperature for injured donor lungs in a pig model when compared to the current clinical standard (4°C) and immediate transplantation. Continuing protective metabolism at 10°C for donor lungs may result in better transplant outcomes.

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.

HEMO2 life® improves renal function independent of cold ischemia time in kidney recipients: A comparison with a large multicenter prospective cohort study

BACKGROUND

M101 is an extracellular hemoglobin isolated from a marine lugworm and is present in the medical device HEMO₂ life®. The clinical investigation OXYOP was a paired kidney analysis (n = 60) designed to evaluate the safety and performance of HEMO₂ life® used as an additive to preservation solution in renal transplantation. The secondary efficacy endpoints showed less delayed graft function (DGF) and better renal function in the HEMO₂ life® group but due to the study design cold ischemia time (CIT) was longer in the contralateral kidneys.

METHODS

An additional analysis was conducted including OXYOP patients and patients from the ASTRE database (n = 6584) to verify that the decrease in DGF rates observed in the HEMO₂ life® group may not be due solely to the shorter CIT but also to HEMO₂ life® performance. Kaplan-Meier estimate curves of cumulative probability of achieving a creatinine level below 250 µmol/L were generated and compared in both groups. A Cox model was used to test the effect of the explanatory variables (use of HEMO₂ life® and CIT). Finally, a bootstrap strategy was used to randomly select smaller samples of patients and test them for statistical comparison in the ASTRE database.

RESULTS

Kaplan-Meier estimate curves confirmed the existence of a relation between DGF and CIT and Cox analysis showed a benefit in the HEMO₂ life® group regardless of the associated CIT. Boostrap analysis confirmed these results.

CONCLUSIONS

The present study suggested that the better recovery of renal function observed among kidneys preserved with HEMO₂ life® in the OXYOP study is a therapeutic benefit of this breakthrough innovative medical device.

Hemoglobin-Based Oxygen Carriers: Potential Applications in Solid Organ Preservation

Ameliorating graft injury induced by ischemia and hypoxia, expanding the donor pool, and improving graft quality and recipient prognosis are still goals pursued by the transplant community. The preservation of organs during this process from donor to recipient is critical to the prognosis of both the graft and the recipient. At present, static cold storage, which is most widely used in clinical practice, not only reduces cell metabolism and oxygen demand through low temperature but also prevents cell edema and resists apoptosis through the application of traditional preservation solutions, but these do not improve hypoxia and increase oxygenation of the donor organ. In recent years, improving the ischemia and hypoxia of grafts during preservation and repairing the quality of marginal donor organs have been of great concern. Hemoglobin-based oxygen carriers (HBOCs) are “made of” natural hemoglobins that were originally developed as blood substitutes but have been extended to a variety of hypoxic clinical situations due to their ability to release oxygen. Compared with traditional preservation protocols, the addition of HBOCs to traditional preservation protocols provides more oxygen to organs to meet their energy metabolic needs, prolong preservation time, reduce ischemia–reperfusion injury to grafts, improve graft quality, and even increase the number of transplantable donors. The focus of the present study was to review the potential applications of HBOCs in solid organ preservation and provide new approaches to understanding the mechanism of the promising strategies for organ preservation.

The Year in Cardiothoracic Transplant Anesthesia: Selected Highlights From 2020 Part I - Lung Transplantation

This special article focuses on the highlights in cardiothoracic transplantation literature in the year 2020. Part I encompasses the recent literature on lung transplantation, including the advances in preoperative assessment and optimization, donor management, including the use of ex-vivo lung perfusion, recipient management, including those who have been infected with coronavirus disease 2019, updates on the perioperative management, including the use of extracorporeal membrane oxygenation, and long-term outcomes.

A therapeutic oxygen carrier isolated from Arenicola marina decreases amanitin-induced hepatotoxicity

The amanitins (namely α- and β-amanitin) contained in certain mushrooms are bicyclic octapeptides that, when ingested, are responsible for potentially lethal hepatotoxicity. M101 is an extracellular hemoglobin extracted from the marine worm Arenicola marina. It has intrinsic Cu/Zn-SOD-like activity and is currently used as an oxygen carrier in organ preservation solutions. Our present results suggest that M101 might be effective in reducing amanitin-induced hepatotoxicity and may have potential for therapeutic development.

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.

Combating hypoxemia in COVID-19 patients with a natural oxygen carrier, HEMO2Life® (M101)

BACKGROUND

Infection with SARS-CoV-2 is responsible for the COVID-19 crisis affecting the whole world. This virus can provoke acute respiratory distress syndrome (ARDS) leading to overcrowed the intensive care unit (ICU). Over the last months, worldwide experience demonstrated that the ARDS in COVID-19 patients are in many ways "atypical". The mortality rate in ventilated patients is high despite the application of the gold standard treatment (protective ventilation, curare, prone position, inhaled NO). Several studies suggested that the SARS-CoV-2 could interact negatively on red blood cell homeostasis. Furthermore, SarsCov2 creates Reactive Oxygen Species (ROS), which are toxic and generate endothelial dysfunction. Hypothesis/objective(s) We hypothesis that HEMO2Life® administrated intravenously is safe and could help symptomatically the patient condition. It would increase arterial oxygen content despite lung failure and allow better tissue oxygenation control. The use of HEMO2Life® is also interesting due to its anti-oxidative effect preventing cytokine storm induced by the SARS-CoV-2. Evaluation of the hypothesis: Hemarina is based on the properties of the hemoglobin of the Arenicola marina sea-worm (HEMO2Life®). This extracellular hemoglobin has an oxygen capacity 40 times greater than the hemoglobin of vertebrates. Furthermore, the size of this molecule is 250 times smaller than a human red blood cell, allowing it to diffuse in all areas of the microcirculation, without diffusing outside the vascular sector. It possesses an antioxidative property du a Superoxide Dismutase Activity. This technology has been the subject of numerous publications and HEMO2Life® was found to be well-tolerated and did not induce toxicity. It was administered intravenously to hamsters and rats, and showed no acute effect on heart rate and blood pressure and did not cause microvascular vasoconstriction. In preclinical in vivo models (mice, rats, and dogs), HEMO2Life® has enabled better tissue oxygenation, especially in the brain. This molecule has already been used in humans in organ preservation solutions and the patients showed no abnormal clinical signs.

CONSEQUENCES OF THE HYPOTHESIS

The expected benefits of HEMO2Life® for COVID-19 patients are improved survival, avoidance of tracheal intubation, shorter oxygen supplementation, and the possibility of treating a larger number of patients as molecular respirator without to use an invasive machine.

Ex vivo lung perfusion for donor lung assessment and repair: a review of translational interspecies models

For patients with end-stage lung disease, lung transplantation is a lifesaving therapy. Currently however, the number of patients who require a transplant exceeds the number of donor lungs available. One of the contributing factors to this is the conservative mindset of physicians who are concerned about transplanting marginal lungs due to the potential risk of primary graft dysfunction. Ex vivo lung perfusion (EVLP) technology has allowed for the expansion of donor pool of organs by enabling assessment and reconditioning of these marginal grafts before transplant. Ongoing efforts to optimize the therapeutic potential of EVLP are underway. Researchers have adopted the use of different large and small animal models to generate translational preclinical data. This includes the use of rejected human lungs, pig lungs, and rat lungs. In this review, we summarize some of the key current literature studies relevant to each of the major EVLP model platforms and identify the advantages and disadvantages of each platform. The review aims to guide investigators in choosing an appropriate species model to suit their specific goals of study, and ultimately aid in translation of therapy to meet the growing needs of the patient population.

A therapeutic oxygen carrier isolated from Arenicola marina decreased P. gingivalis induced inflammation and tissue destruction

The control of inflammation and infection is crucial for periodontal wound healing and regeneration. M101, an oxygen carrier derived from Arenicola marina, was tested for its anti-inflammatory and anti-infectious potential based on its anti-oxidative and tissue oxygenation properties. In vitro, no cytotoxicity was observed in oral epithelial cells (EC) treated with M101. M101 (1 g/L) reduced significantly the gene expression of pro-inflammatory markers such as TNF-α, NF-κΒ and RANKL in P. gingivalis-LPS stimulated and P. gingivalis-infected EC. The proteome array revealed significant down-regulation of pro-inflammatory cytokines (IL-1β and IL-8) and chemokine ligands (RANTES and IP-10), and upregulation of pro-healing mediators (PDGF-BB, TGF-β1, IL-10, IL-2, IL-4, IL-11 and IL-15) and, extracellular and immune modulators (TIMP-2, M-CSF and ICAM-1). M101 significantly increased the gene expression of Resolvin-E1 receptor. Furthermore, M101 treatment reduced P. gingivalis biofilm growth over glass surface, observed with live/dead analysis and by decreased P. gingivalis 16 s rRNA expression (51.7%) (p < 0.05). In mice, M101 reduced the clinical abscess size (50.2%) in P. gingivalis-induced calvarial lesion concomitant with a decreased inflammatory score evaluated through histomorphometric analysis, thus, improving soft tissue and bone healing response. Therefore, M101 may be a novel therapeutic agent that could be beneficial in the management of P. gingivalis associated diseases.