Poly(2-ethyl-2-oxazoline)-Conjugated Hemoglobins as a Red Blood Cell Substitute.

Hemoglobin wrapped covalently with poly(2-ethyl-2-oxazoline)s (POx-Hb) is characterized physicochemically and physiologically as an artificial O2 carrier for use as a red blood cell (RBC) substitute. The POx-Hb is generated by linkage of porcine Hb surface-lysines to a sulfhydryl terminus of the POx derivative, with the average binding number of the polymers ascertained as 6. The POx-Hb shows moderately higher colloid osmotic activity and O2 affinity than the naked Hb. Human adult HbA conjugated with POx also possesses equivalent features and O2 binding properties. The POx-Hb solution exhibits good hemocompatibility, with no influence on the functions of platelets, granulocytes, and monocytes. Its circulation half-life in rats is 14 times longer than that of naked Hb. Hemorrhagic shock in rats is relieved sufficiently by infusion of the POx-Hb solution, as revealed by improvements of circulatory parameters. Serum biochemistry tests and histopathological observations indicate no acute toxicity or abnormality in the related organs. All results indicate that POx-Hb represents an attractive alternative for RBCs and a useful O2 therapeutic reagent in transfusion medicine.

Selective Attachment of Polyethylene Glycol to Hemerythrin for Potential Use in Blood Substitutes.

Due to its ability to reversibly bind O2, alongside a relatively low redox reactivity and a limited cytotoxicity, the oxygen-carrying protein hemerythrin has been considered as an alternative to hemoglobin in preparing blood substitutes. In order to increase the hydrodynamic volume and lower antigenicity, two site-directed variants, H82C and K92C, were engineered that contained a single cysteine residue on the surface of each hemerythrin octamer for the specific attachment of polyethylene glycol (PEG). A sulfhydryl-reactive PEGylation reagent with a 51.9 Å spacer arm was used for selective cysteine derivatization. The mutants were characterized by UV-vis spectroscopy, size-exclusion chromatography, oxygen affinity, and autooxidation rate measurements. The H82C variant showed altered oligomeric behavior compared to the wild-type and was unstable in the met form. The PEGylated K92C variant is reasonably stable, displays an oxygen affinity similar to that of the wild-type, and shows an increased rate of autoxidation; the latter disadvantage may be counteracted by further chemical modifications.

Long non­coding RNA LINC01960­201 hinders decidualization of endometrial stromal cell in endometriosis: Relevance to endometrial receptivity.

Emerging data have indicated that long non­coding RNAs (lncRNA) are associated with the pathogenesis of endometriosis. However, few are associated with endometriosis­associated infertility. In addition, to the best of our knowledge, the role of lncRNAs in decidual formation during the window of implantation with endometriosis has not been reported to date. Based on our previous results, the aim of the present study was to explore the role of lncRNA long intergenic non­protein coding RNA (LINC)01960­201 in in vitro decidualization of endometrial stromal cells in endometriosis during the window of implantation, as well as to explore the biological function of LINC01960­201, and the regulation of a disintegrin and metalloproteinase with thrombospondin motifs 7 (ADAMTS7), hsa­microRNA (miR)­760 and hsa­miR­608 in the decidualization of endometrial stromal cells with endometriosis. Using miRanda, PITA and RNAhybrid, the present study predicted which miRs share the common target gene ADAMTS7 with LINC01960­201 and the existence of regulatory targets. Dual luciferase vectors were constructed to extract the plasmids and measure the relative fluorescence values in order to estimate target regulatory association between LINC01960­201, ADAMTS7 and miRs. Mid­secretory endometrial tissues were collected from women with endometriosis­associated infertility. From these tissues, endometrial stromal cells were extracted and cultured as primary cultures. Medroxyprogesterone acetate (MPA) and 8­Bromoadenosine 3',5'­cyclic monophosphate (8­Br­cAMP) were added to induce in vitro decidualization, and to knockdown LINC01960­201 and transfect a hsa­miR­608 mimic at the same time. Reverse transcription­quantitative PCR and western blotting were conducted to compare the difference in gene expression between the experimental and negative control groups. No regulatory sites between LINC01960­201 and hsa­miR­608 were identified; however, potential regulatory sites were detected between hsa­miR­608 and the 3'­untranslated region (UTR) of ADAMTS7, whereas neither the 3'­UTR of LINC01960­201 or the 3'­UTR of ADAMTS7 had any regulatory targets with hsa­miR­760. During the process of decidualization of endometrial stromal cells by in vitro induction, the expression of hsa­miR­608 in the knockdown group was significantly higher compared with that of the negative control group after LINC01960­201­knockdown, and the expression of ADAMTS7 in the transfection group was significantly lower compared with that of the negative control group after hsa­miR­608 mimic transfection. In conclusion, it was hypothesized that LINC01960­201 played a notable regulatory role in the decidualization of endometrial stromal cells in women with endometriosis during the window of implantation, and its abnormal expression may lead to the decline of endometrial receptivity and recurrent abortions.

An Overview of Current Position on Cell Therapy in Transfusion Science and Medicine: From Fictional Promises to Factual and Perspectives from Red Cell Substitution to Stem Cell Therapy.

Stem cell therapy is a relatively novel field of investigation, in which either differentiated cells or stem cells capable of differentiation are transplanted into an individual with the objective of yielding specific cell types in the damaged tissue and consequently restoring its function. The most successful example of cell therapy is hematopoietic stem cell transplantation, leading to regeneration of a patient's blood cells, now a widely established procedure for many oncologic and non-oncologic diseases. Innovative cell-based therapies are being developed to replace, regenerate or repair injured, absent, or diseased tissues and organs. However, cell therapy bioproducts are based on their inherent biological features such as proliferation, migratory, capability, plasticity, and capacity of self-renewal, posing serious challenges during such bioproduct development. The extraordinary promise of stem cells for future treatments of otherwise intractable diseases has raised great hope and expectations in patients, advocates, physicians, and researchers alike. However, despite thousands of scientific publications and research programs, increased efforts need to be put into the identification of the factors involved, biological mechanisms and materials that affect safety/ efficacy, and into the design of cost-effective methods for the harvesting, expansion, manipulation and purification of the cells.

Systemic and microvascular comparison of Lactated Ringer's solution, VIR-HBOC, and alpha-alpha crosslinked haemoglobin-based oxygen carrier in a rat 10% topload model.

Medical support for traumatic haemorrhage is lacking for far-forward combat units. VIR-HBOC (haemoglobin-based oxygen carrier) is a novel biological therapeutic under development as a field-stable resuscitation fluid. HBOCs have a long history of complications, chief among them is vasoconstrictive hypertension, which must be resolved before efficacy testing. As such, VIR-HBOC was compared against Lactated Ringers (LRS; vehicle) and a cross-linked haemoglobin (ααHb; a known vasoactive HBOC) in a rat topload model. Twenty-three male, Sprague Dawley rats were randomly assigned to receive a 10% infusion (estimated total blood volume) of one test article while normotensive and under anaesthesia. Cardiovascular, blood chemistry and oximetry, microvascular arteriolar diameters, and interstitial tissue oxygenation parameters were measured. Circulatory half-life was calculated by plasma total haemoglobin. Treatment with ααHb caused immediate increases in mean arterial pressure compared to LRS and VIR-HBOC groups, and corresponding arteriolar vasoconstriction (p < .05), which did not occur for LRS or VIR-HBOC. Circulatory half-lives for VIR-HBOC and ααHb were calculated as 340 and 157 min, respectively. This first report of VIR-HBOC showed no evidence of a hypertensive or vasoactive effect. It was well-tolerated over the eight-hour time course of this topload model, which warrants further investigation in studies of haemorrhagic shock.

Artificial Oxygen Carriers-Past, Present, and Future-a Review of the Most Innovative and Clinically Relevant Concepts.

Blood transfusions are a daily practice in hospitals. Since these products are limited in availability and have various, harmful side effects, researchers have pursued the goal to develop artificial blood components for about 40 years. Development of oxygen therapeutics and stem cells are more recent goals. Medline (https://www.ncbi.nlm.nih.gov/pubmed/?holding=ideudelib), ClinicalTrials.gov (https://clinicaltrials.gov), EU Clinical Trials Register (https://www.clinicaltrialsregister.eu), and Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au) were searched up to July 2018 using search terms related to artificial blood products in order to identify new and ongoing research over the last 5 years. However, for products that are already well known and important to or relevant in gaining a better understanding of this field of research, the reader is punctually referred to some important articles published over 5 years ago. This review includes not only clinically relevant substances such as heme-oxygenating carriers, perfluorocarbon-based oxygen carriers, stem cells, and organ conservation, but also includes interesting preclinically advanced compounds depicting the pipeline of potential new products. In- depth insights into specific benefits and limitations of each substance, including the biochemical and physiologic background are included. "Fancy" ideas such as iron-based substances, O2 microbubbles, cyclodextranes, or lugworms are also elucidated. To conclude, this systematic up-to-date review includes all actual achievements and ongoing clinical trials in the field of artificial blood products to pursue the dream of artificial oxygen carrier supply. Research is on the right track, but the task is demanding and challenging.

Engineering tyrosine residues into hemoglobin enhances heme reduction, decreases oxidative stress and increases vascular retention of a hemoglobin based blood substitute.

Hemoglobin (Hb)-based oxygen carriers (HBOC) are modified extracellular proteins, designed to replace or augment the oxygen-carrying capacity of erythrocytes. However, clinical results have generally been disappointing due to adverse side effects, in part linked to the intrinsic oxidative toxicity of Hb. Previously a redox-active tyrosine residue was engineered into the Hb ß subunit (ßF41Y) to facilitate electron transfer between endogenous antioxidants such as ascorbate and the oxidative ferryl heme species, converting the highly oxidizing ferryl species into the less reactive ferric (met) form. We inserted different single tyrosine mutations into the α and ß subunits of Hb to determine if this effect of ßF41Y was unique. Every mutation that was inserted within electron transfer range of the protein surface and the heme increased the rate of ferryl reduction. However, surprisingly, three of the mutations (ßT84Y, αL91Y and ßF85Y) also increased the rate of ascorbate reduction of ferric(met) Hb to ferrous(oxy) Hb. The rate enhancement was most evident at ascorbate concentrations equivalent to that found in plasma (< 100 µM), suggesting that it might be of benefit in decreasing oxidative stress in vivo. The most promising mutant (ßT84Y) was stable with no increase in autoxidation or heme loss. A decrease in membrane damage following Hb addition to HEK cells correlated with the ability of ßT84Y to maintain the protein in its oxygenated form. When PEGylated and injected into mice, ßT84Y was shown to have an increased vascular half time compared to wild type PEGylated Hb. ßT84Y represents a new class of mutations with the ability to enhance reduction of both ferryl and ferric Hb, and thus has potential to decrease adverse side effects as one component of a final HBOC product.

Novel Redox Active Tyrosine Mutations Enhance the Regeneration of Functional Oxyhemoglobin from Methemoglobin: Implications for Design of Blood Substitutes.

Heme mediated oxidative toxicity has been linked to adverse side effects in Hemoglobin Based Oxygen Carriers (HBOC), initiated by reactive ferryl (FeIV) iron and globin based free radical species. We recently showed that the addition of a redox active tyrosine residue in the beta subunit (ßF41Y) of recombinant hemoglobin had the capability to decrease lipid peroxidation by facilitating the reduction of FeIV iron by plasma antioxidants such as ascorbate. In order to explore this functionality further we created a suite of tyrosine mutants designed to be accessible for both reductant access at the protein surface, yet close enough to the heme cofactor to enable efficient electron transfer to the FeIV. The residues chosen were: ßF41Y; ßK66Y; ßF71Y; ßT84Y; ßF85Y; and ßL96Y. As with ßF41Y, all mutants significantly enhanced the rate of ferryl (FeIV) to ferric (FeIII) reduction by ascorbate. However, surprisingly a subset of these mutations (ßT84Y, and ßF85Y) also enhanced the further reduction of ferric (FeIII) to ferrous (FeII) heme, regenerating functional oxyhemoglobin. The largest increase was seen in ßT84Y with the percentage of oxyhemoglobin formed from ferric hemoglobin in the presence of 100 µM ascorbate over a time period of 60 min increasing from 10% in ßF41Y to over 50% in ßT84Y. This increase was accompanied by an increased rate of ascorbate consumption. We conclude that the insertion of novel redox active tyrosine residues may be a useful component of any recombinant HBOC designed for longer functional activity without oxidative side effects.

Recent and prominent examples of nano- and microarchitectures as hemoglobin-based oxygen carriers.

Blood transfusions, which usually consist in the administration of isolated red blood cells (RBCs), are crucial in traumatic injuries, pre-surgical conditions and anemias. Although RBCs transfusion from donors is a safe procedure, donor RBCs can only be stored for a maximum of 42 days under refrigerated conditions and, therefore, stockpiles of RBCs for use in acute disasters do not exist. With a worldwide shortage of donor blood that is expected to increase over time, the creation of oxygen-carriers with long storage life and compatibility without typing and cross-matching, persists as one of the foremost important challenges in biomedicine. However, research has so far failed to produce FDA approved RBCs substitutes (RBCSs) for human usage. As such, due to unacceptable toxicities, the first generation of oxygen-carriers has been withdrawn from the market. Being hemoglobin (Hb) the main component of RBCs, a lot of effort is being devoted in assembling semi-synthetic RBCS utilizing Hb as the oxygen-carrier component, the so-called Hb-based oxygen carriers (HBOCs). However, a native RBC also contains a multi-enzyme system to prevent the conversion of Hb into non-functional methemoglobin (metHb). Thus, the challenge for the fabrication of next-generation HBOCs relies in creating a system that takes advantage of the excellent oxygen-carrying capabilities of Hb, while preserving the redox environment of native RBCs that prevents or reverts the conversion of Hb into metHb. In this review, we feature the most recent advances in the assembly of the new generation of HBOCs with emphasis in two main approaches: the chemical modification of Hb either by cross-linking strategies or by conjugation to other polymers, and the Hb encapsulation strategies, usually in the form of lipidic or polymeric capsules. The applications of the aforementioned HBOCs as blood substitutes or for oxygen-delivery in tissue engineering are highlighted, followed by a discussion of successes, challenges and future trends in this field.

Long term safety and immunological effects of a nanobiotherapeutic, bovine poly-[hemoglobin-catalase-superoxide dismutase-carbonic anhydrase], after four weekly 5% blood volume top-loading followed by a challenge of 30% exchange transfusion.

The long-term safety and immunological effects of bovine poly-[haemoglobin-catalase-superoxide dismutase-carbonic anhydrase] in rats are studied by four-weekly 5% blood volume top-loading infusions followed by 30% blood volume exchange transfusion. There is no significant difference in growth, biochemistry and blood pressure between the control group receiving lactated ringer solution and those receiving the bovine poly-[haemoglobin-catalase-superoxide dismutase-carbonic anhydrase]. There is no significant change in mean arterial pressures (MAP) before and after each weekly top-loading infusion. After both the four weekly top-loading and the 30% exchange transfusions, the following safety and immune response evaluations are carried out. These include general studies on Ouchterlony double diffusion, total IgG and IgM, and complement activation. This is followed by quantitative measurements of specific antibodies against each of the following bovine components: Hb, CAT, SOD and CA in bovine poly-[haemoglobin-catalase-superoxide dismutase-carbonic anhydrase]. After the four weekly top-loading, each rat received a challenge of 30% blood volume exchange transfusion. The MAP, histamine and tryptase levels are tested before and after the 30% exchange transfusion. There are no anaphylactic reactions as shown by the MAP or histamine and tryptase. The results showed no safety problem nor adverse immune responses. All the rats survived when followed for one week after the 30% exchange transfusion.

Comparison of the oxidative reactivity of recombinant fetal and adult human hemoglobin: implications for the design of hemoglobin-based oxygen carriers.

Hemoglobin (Hb)-based oxygen carriers (HBOCs) have been engineered to replace or augment the oxygen carrying capacity of erythrocytes. However, clinical results have generally been disappointing, in part due to the intrinsic oxidative toxicity of Hb. The most common HBOC starting material is adult human or bovine Hb. However, it has been suggested that fetal Hb may offer advantages due to decreased oxidative reactivity. Large-scale manufacturing of HBOC will likely and ultimately require recombinant sources of human proteins. We, therefore, directly compared the functional properties and oxidative reactivity of recombinant fetal (rHbF) and recombinant adult (rHbA) Hb. rHbA and rHbF produced similar yields of purified functional protein. No differences were seen in the two proteins in: autoxidation rate; the rate of hydrogen peroxide reaction; NO scavenging dioxygenase activity; and the NO producing nitrite reductase activity. The rHbF protein was: less damaged by low levels of hydrogen peroxide; less damaging when added to human umbilical vein endothelial cells (HUVEC) in the ferric form; and had a slower rate of intrinsic heme loss. The rHbA protein was: more readily reducible by plasma antioxidants such as ascorbate in both the reactive ferryl and ferric states; less readily damaged by lipid peroxides; and less damaging to phosphatidylcholine liposomes. In conclusion in terms of oxidative reactivity, there are advantages and disadvantages to the use of rHbA or rHbF as the basis for an effective HBOC.

Comprehensive Biochemical and Biophysical Characterization of Hemoglobin-Based Oxygen Carrier Therapeutics: All HBOCs Are Not Created Equally.

The development of hemoglobin (Hb)-based oxygen carriers (HBOCs) has been hampered because of safety concerns in humans. Chemical and/or genetic modifications of the Hb introduce varied structural and conformational constraint on the molecule that resulted in proteins with diverse allosteric responses, nitrosative and oxidative side reactions. Here, we present for the first time a comprehensive biochemical and biophysical comparison of human, bovine, and genetically engineered HBOCs that have been tested in humans. We evaluate oxygen equilibrium and ligand binding kinetics under different experimental conditions as well as their autoxidation kinetics, redox reactions, and heme release. We determined the effects of HBOCs on cellular redox states and mitochondrial respiration. Taken together, these experiments provide a better understanding of the relationship between the structure-function and oxidative reactivity of these proteins. One can therefore select independently among these diverse properties to engineer a safe and effective HBOC with improved biochemical/biophysical characteristics.

Conjugation with 20 kDa dextran decreases the autoxidation rate of bovine hemoglobin.

Haemoglobin-based oxygen carrier (HBOC) is highly susceptible to autoxidation that renders a series of tissue and cellular toxicities. HBOC is prepared by chemical modification of haemoglobin (Hb), which typically increases the autoxidation rate of Hb. Thus, it is necessary to decrease the autoxidation of HBOC. In the present study, two dextran-bHb conjugates (dex20-bHb and dex40-bHb) were prepared by conjugation with 20 kDa or 40 kDa dextrans, where the thiol group of Cys-93(ß) was reversibly protected. The autoxidation rate of bHb was decreased by conjugation with 20 kDa dextran and maintained by conjugation with 40 kDa dextran. In order to understand the low autoxidation rate of dex20-bHb, the effects of aldehyde modification and dextran on the autoxidation rate of dex20-bHb were investigated. The high oxygen affinity, high tetramer stability and dextran itself were found to decrease the autoxidation rate of dex20-bHb. The conjugated dextran had a predominant effect on decreasing the autoxidation rate of bHb, which was particularly promising for the potential development of safe HBOCs. Conjugation with dextran is of general significance to decrease the oxidation process of the heme-containing proteins, such as Hb and myoglobin.

Hemoglobin-Based Oxygen Carrier (HBOC) Development in Trauma: Previous Regulatory Challenges, Lessons Learned, and a Path Forward.

Historically, hemoglobin-based oxygen carriers (HBOCs) were being developed as "blood substitutes," despite their transient circulatory half-life (~ 24 h) vs. transfused red blood cells (RBCs). More recently, HBOC commercial development focused on "oxygen therapeutic" indications to provide a temporary oxygenation bridge until medical or surgical interventions (including RBC transfusion, if required) can be initiated. This included the early trauma trials with HemAssist ® (BAXTER), Hemopure ® (BIOPURE) and PolyHeme ® (NORTHFIELD) for resuscitating hypotensive shock. These trials all failed due to safety concerns (e.g., cardiac events, mortality) and certain protocol design limitations. In 2008 the Food and Drug Administration (FDA) put all HBOC trials in the US on clinical hold due to the unfavorable benefit:risk profile demonstrated by various HBOCs in different clinical studies in a meta-analysis published by Natanson et al. (2008). During standard resuscitation in trauma, organ dysfunction and failure can occur due to ischemia in critical tissues, which can be detected by the degree of lactic acidosis. SANGART'S Phase 2 trauma program with MP4OX therefore added lactate >5 mmol/L as an inclusion criterion to enroll patients who had lost sufficient blood to cause a tissue oxygen debt. This was key to the successful conduct of their Phase 2 program (ex-US, from 2009 to 2012) to evaluate MP4OX as an adjunct to standard fluid resuscitation and transfusion of RBCs. In 2013, SANGART shared their Phase 2b results with the FDA, and succeeded in getting the FDA to agree that a planned Phase 2c higher dose comparison study of MP4OX in trauma could include clinical sites in the US. Unfortunately, SANGART failed to secure new funding and was forced to terminate development and operations in Dec 2013, even though a regulatory path forward with FDA approval to proceed in trauma had been achieved.

Hemoglobin extravasation in the brain of rats exchange-transfused with hemoglobin-based oxygen carriers.

Haemoglobin (Hb)-based oxygen carriers are under consideration as oxygen therapeutics. Their effect on apoptosis is critical, because the onset of pro-apoptotic pathways may lead to tissue damage. MP4OX, a polyethylene glycol-conjugated human Hb preserves the baseline level of neuron apoptosis with respect to sham. Here we develop a method for measuring Hb extravasation in brain. We exchange transfused rats by haemorrhaging 50% of their blood with simultaneous, isovolemic replacement with Hextend (negative control), MP4OX, or αα-cross-linked Hb. Animals were sacrificed 2 h after transfusion, brain tissue was harvested and processed for double-staining immunofluorescence, whereby Hb ? chain and NeuN (a neuron protein) were stained and quantitated. Whereas Hextend did not induce Hb extravasation, in both MP4OX and ??Hb brains Hb molecules were detected outside neurons. The level of extravasated Hb chains was > 3-fold higher in Hb compared to MP4OX. Western blot analysis revealed that the expression levels of protein related to redox imbalance (e.g., Nrf2, iNOS and ERK phosphorylation) were higher in ααHb than MP4OX. In conclusions, higher Hb extravasation in ααHb than MP4OX induces redox imbalance, which causes higher anti-oxidant response. Whereas Nrf2 response may be considered protective, iNOS response appears damaging.

Influence of Molecular Structure on O2-Binding Properties and Blood Circulation of Hemoglobin‒Albumin Clusters.

A hemoglobin wrapped covalently by three human serum albumins, a Hb-HSA3 cluster, is an artificial O2-carrier with the potential to function as a red blood cell substitute. This paper describes the synthesis and O2-binding properties of new hemoglobin‒albumin clusters (i) bearing four HSA units at the periphery (Hb-HSA4, large-size variant) and (ii) containing an intramolecularly crosslinked Hb in the center (XLHb-HSA3, high O2-affinity variant). Dynamic light scattering measurements revealed that the Hb-HSA4 diameter is greater than that of either Hb-HSA3 or XLHb-HSA3. The XLHb-HSA3 showed moderately high O2-affinity compared to the others because of the chemical linkage between the Cys-93(ß) residues in Hb. Furthermore, the blood circulation behavior of 125I-labeled clusters was investigated by assay of blood retention and tissue distribution after intravenous administration into anesthetized rats. The XLHb-HSA3 was metabolized faster than Hb-HSA3 and Hb-HSA4. Results suggest that the molecular structure of the protein cluster is a factor that can influence in vivo circulation behavior.

Subunit-directed click coupling via doubly cross-linked hemoglobin efficiently produces readily purified functional bis-tetrameric oxygen carriers.

While cross-linked hemoglobin (Hb) tetramers can deliver oxygen as a supplement to red cells, they also cause unacceptable increases in blood pressure, presumably from their penetration of the linings of blood vessels (endothelia) where the internal hemes bind endogenous nitric oxide (NO). This penetration would lower the local concentration of NO that normally induces vasodilation. Enlarging the effective size of the oxygen-carrying protein by coupling two Hbs can prevent their extravasation. Efficient and selective protein-protein coupling to produce those species has been a significant challenge. Introduction of an azide within a protein provides a directionally-oriented reaction site for utilization of the Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) in the protein-protein-coupling process based on solubility-directed sequential addition to a bis-alkyne. However, it is known that Hb with an azide-containing cross-link between α-subunits is unreactive in CuAAC. To direct reaction away from the α-subunits of Hb, a specific fumaryl cross-link is installed exclusively between the most reactive sites on those subunits, thereby blocking the α-99 lysyl groups and preventing any further reaction. This modification allows installation of an azide-containing cross-link exclusively between lysine-82 ε-amino groups of the ß-subunits of Hb. The multiply interconnected sites establish a geometry that permits initial interfacial interaction of the cross-linked Hb-azide with Cu(i) and a bis-alkyne. After coupling, the protein-linked azide product undergoes CuAAC at the remaining alkyne with a second cross-linked Hb-azide, producing a fully functional cross-linked Hb bis-tetramer whose oxygenation and structural properties include cooperativity and oxygen affinity that should be suitable for testing as an alternative to red cells in transfusions.

Potential electron mediators to extract electron energies of RBC glycolysis for prolonged in vivo functional lifetime of hemoglobin vesicles.

Developing a functional blood substitute as an alternative to donated blood for clinical use is believed to relieve present and future blood shortages, and to reduce the risks of infection and blood type mismatching. Hemoglobin vesicle (HbV) encapsulates a purified and concentrated human-derived Hb solution in a phospholipid vesicle (liposome). The in vivo safety and efficacy of HbV as a transfusion alternative have been clarified. Auto-oxidation of ferrous Hb in HbV gradually increases the level of ferric methemoglobin (metHb) and impairs the oxygen transport capabilities. The extension of the functional half-life of HbV has recently been proposed using an electron mediator, methylene blue (MB), which acts as a shuttle between red blood cells (RBC) and HbV. MB transfers electron energies of NAD(P)H, produced by RBC glycolysis, to metHb in HbV. Work presented here focuses on screening of 15 potential electron mediators, with appropriate redox potential and water solubility, for electron transfer from RBC to HbV. The results are assessed with regard to the chemical properties of the candidates. The compounds examined in this study were dimethyl methylene blue (DMB), methylene green, azure A, azure B, azure C, toluidine blue (TDB), thionin acetate, phenazine methosulfate, brilliant cresyl blue, cresyl violet, gallocyanine, toluylene blue, indigo carmine, indigotetrasulfonate, and MB. Six candidates were found to be unsuitable because of their insufficient diffusion across membranes, or overly high or nonexistent reactivity with relevant biomolecules. However, 9 displayed favorable metHb reduction. Among the suitable candidates, phenothiazines DMB and TDB exhibited effectiveness like MB did. In comparison to MB, they showed faster reduction by electron-donating NAD(P)H, coupled with showing a lower rate of reoxidation in the presence of molecular oxygen. Ascertaining the best electron mediator can provide a pathway for extending the lifetime and efficiency of potential blood substitutes.

Normothermic preservation of the rat hind limb with artificial oxygen-carrying hemoglobin vesicles.

BACKGROUND: For managing major limb amputation, it is important to consider ischemic time and reperfusion injury by free radicals after the blood supply is reestablished. State of preservation during transplant surgery is crucial for the survival and function of the tissue, graft, or organ. In this study, we confirmed the effect of intermittent blood flow in rat ischemic hind limb and developed a new oxygenic preservation method using artificial oxygen carrying hemoglobin vesicles (HbVs). METHODS: We first compared a continuous ischemic model and an intermittent reflow model on rat hind limb. At postoperative day 7, hind limbs were evaluated. Next, we performed total amputation, normothermic preservation by perfusion with extracellular-trehalose-Kyoto (ETK) solution or HbV, and microsurgical replantation of the left hind limb. Venous efflux was analyzed, the amputated limb evaluated after 6 hr perfusion, and the replantation outcome of each model was compared. RESULTS: In our early study, 24 hr continuous ischemic model necrotized, but intermittent reflow model almost survived except for partial necrosis at postoperative day 7. Scar tissue on the right limb showed myonecrosis and infiltration of inflammatory cells. Skeletal muscle on the right limb was structurally well maintained. Hemoglobin vesicle-treated limbs appeared to have much better oxygenation than ETK-treated limbs. Aerobic respiration remained in the amputated limb, gastrocnemius muscle was well maintained, and the overall replantation was successful in the limb preserved using HbV. CONCLUSION: These studies demonstrated that oxygenic preservation is effective for rat ischemic limb, suggesting that this method may be useful for other replantation and transplantation surgeries.

En torno a los hemoderivados / About blood products

La transfusión es una necesidad permanente, y la amplitud con la que es utilizada exige que deba garantizarse su calidad y seguridad para evitar, en particular, la transmisión de enfermedades. Ha de ser un tratamiento personalizado. Las funciones de enfermería son de especial importancia así como los cuidados que se requieren. El objetivo del presente estudio es conocer la variabilidad práctica de los profesionales de enfermería del centro hospitalario, sobre la extracción de muestras pretransfusionales y la administración de hemoderivados. Para lo cual se realizó el envío de un cuestionario para su posterior cumplimentación en formato on-line, que garantizaba el total anonimato. Han contestado a la encuesta 180 profesionales. El 74.4% de los enfermeros dice que la transfusión de hemoderivados sólo se puede administrar de forma simultánea con suero fisiológico. Un 56.1% refiere que cada concentrado transfundido de hematíes aumenta la hemoglobina en 1gr/dl. Hemos encontrado un consenso entre las recomendaciones científicas y las contestaciones realizadas por los diferentes profesionales, hecho que se reafirma con el escaso índice de notificaciones adversas que se han registrado en nuestro trabajo. La elaboración e implantación de una guía de actuación en cuanto a la administración de hemoderivados se hace imprescindible (AU)

Transfusion is an ongoing need, and as widely used it requires that quality and safety should be ensured to avoid, in particular, the transmission of diseases. It must be a custom treatment. Nursing roles are particularly important as the care required. The aim of this study is to determine the variability of nursing skills on the extraction of pre-transfusion samples and administration of blood products. Anonymous questionnaires were sent out on-line for subsequent filling and 180 nursing professionals participated. 74.4% of nurses said that blood transfusion can only be administered simultaneously with normal saline, 56.1% reported that each transfused packed red blood cells increases hemoglobin 1 g / dl. We found a consensus among the scientific recommendations and the responses made by different professionals, a fact that is confirmed by the low rate of adverse notifications registered in our study. The development and implementation of policy guidance regarding the administration of blood products is essential (AU)