Blood transfusion: old blood, new blood or no blood.

Vigorous blood transfusion has long been regarded as having an essential role in the management of acute gastrointestinal haemorrhage. Two new studies, one a nationwide audit of acute gastrointestinal haemorrhage in the UK and another, a complex physiological study of stored blood from the USA, offer new insights.

An approach to prevent the severe adverse events associated with transfusion of FDA-approved blood products.

There have been several retrospective studies reporting severe adverse events of mortality and morbidity associated with blood transfusions. Mortality and morbidity associated with posttransfusion infection, transfusion related acute lung injury (TRALI), and systemic inflammatory response syndrome (SIRS) have been reported in patients undergoing cardiac surgery, after massive transfusions for severe traumatic injuries, and after transfusions for elective and emergency indications. After 35 days of storage at 4 degrees C in additive solutions, RBC have 24-h posttransfusion survival values of 75% but do not function satisfactorily. For RBC to function satisfactorily shortly after transfusion, they should be stored at 4 degrees C for no more than 2 weeks. Yet while the FDA requires a 24-h posttransfusion survival value of 75%, there is no requirement for the function of the transfused RBC. It has been shown that red blood cells that circulate and function immediately or shortly after transfusion exert a very important hemostatic effect to reduce the bleeding time and nonsurgical blood loss in anemic and thrombocytopenic patients. Greater restoration of hemostasis is seen with viable and functional RBC transfusions than with platelets or plasma even though the platelets and plasma proteins may have satisfactory viability and function. The length of storage of the blood products affects their survival and function and the transfusion of nonviable compatible RBC, antibodies to granulocytes and WBC HLA antigens and biologically active substances affects the patient's clinical outcome. One of the easiest ways to prevent the severe adverse events that have been observed is to ensure that the transfused blood products survive and function at an optimum level and that the levels of antibodies to granulocytes and WBC HLA antigens and biologically active substances are eliminated or reduced. The best way to ensure this is to store liquid-preserved leukoreduced human red blood cells at 4 degrees C in additive solutions for no more than 2 weeks and leukoreduced platelets at room temperature for no more than 2 days. These liquid-preserved blood products can be used in conjunction with frozen RBC, platelets, and plasma stored in -80 degrees C mechanical freezers and will avoid the need for fresh whole blood and prevent the severe adverse events associated with the transfusion of blood products.

Quantitative analysis of hemoglobin content in polymeric nanoparticles as blood substitutes using Fourier transform infrared spectroscopy.

Based on the penetrability of IR within the polymeric nanoparticles, a novel Fourier transform infrared spectroscopy (FTIR) method, with polyacrylonitrile (PAN) as the internal reference standard, was developed to quantify the hemoglobin (Hb) content in Hb-based polymeric nanoparticles (HbPN). The HbPN was fabricated by double emulsion method from poly(ethylene glycol)-poly(lactic acid)-poly(ethylene glycol) triblock copolymers. Depending on the characteristic un-overlapped IR absorbances at 1540 cm(-1) of Hb (amide II) and at 2241 cm(-1) of PAN(-C[triple bond]N), calibration equations, presenting the peak height ratio of Hb and PAN as a function of the weight ratio of Hb and PAN, were established. This new quantification method is validated and used to the determination Hb content in HbPN. Due to the good results of this calibration strategy, the proposed simple FTIR approach with minimal sample-needed and solvent-free makes it useful for routine analysis of protein content and could be also applied to any other drug/protein encapsulated particles.

[Research progress in estimating parameters of blood substitute function].

The shortage of healthy blood resource and the problem of virus infection have urged the study of blood substitute. The technologies of modified hemoglobin, perfluorocarbons and Hb-vesicles have been developing quickly, and some of which have already been formed into large-scale preparation and production. However, there is no completed evaluation system for the blood substitute at present, and it is still hard to estimate the function of blood substitute completely. This article takes the evaluation of the blood substitute as a key point, discusses the evaluation parameters of blood substitute, and presents the physical and chemical property, the availability and safety as well as the preservation condition of the blood substitute. The data concerned are based on the studies in China and abroad and referred to the latest progress all over the world.

The importance of the effect of shear stress on endothelial cells in determining the performance of hemoglobin based oxygen carriers.

The lack of blood donations and the threat of infections from blood and blood products have led to extensive research into the development of blood substitutes. The latest generation of hemoglobin based oxygen carriers (HBOC) has been shown to induce side effects like hypertension, vasoconstriction, inflammation and oxidative stress. HBOC are able to restore volemia and transport oxygen after a hemorrhagic shock, the reperfusion leading to the restoration of the blood flow in vessels. We propose an innovative approach, more closely emulating clinical situations, to assess the impact of HBOC perfusion on endothelial cells (EC) in vitro. Through this approach we quantified levels of oxidative stress, vasoactive factors and inflammation. EC were cultivated under a laminar flow to reproduce the return of shear stress (SS) during the reperfusion. We showed that heme oxygenase I transcription correlated with changes in oxidatively modified heme and methemoglobin; all were lower under SS. SS induced increased nitric oxide production, which may have implications for the mechanism of in vivo vasoconstriction and hypertension. E-selectin changes under SS were greater than those of ICAM-1. Our results demonstrate how it is essential to include SS in assays attempting to understand the potential vascular side effects of HBOC perfusion.

Substâncias carreadoras de oxigênio à base de hemoglobina: situação atual e perspectivas / Hemoglobin-based blood substitutes: current status and perspectives

JUSTIFICATIVA E OBJETIVOS: Soluções alternativas à transfusäo de sangue têm sido estudadas desde a década de 50. O objetivo deste estudo é apresentar a situaçäo atual e as perspectivas futuras das substâncias carreadoras de oxigênio à base de hemoglobina. CONTEUDO: São apresentadas as potenciais áreas de aplicaçäo, bem como estudos clínicos envolvendo as principais moléculas de hemoglobina desenvolvidas, suas vantagens e limitações. CONCLUSÕES: Vários estudos aleatórios demonstraram eficácia com o propósito de evitar ou reduzir a transfusäo sangüínea; entretanto, algumas limitações existem, sendo que o futuro substituto sangüíneo deverá, no mínimo, retratar a segurança e a eficácia do sangue em si

Assessment of newly developed perfluorocarbon emulsion: oxygen carrying capacity as the blood substitute in vivo.

This study provides the evaluation of oxygen carrying capacity of the novel perfluorocarbon emulsion (Neo-PFC) produced by the new emulsifying technology named High Pressure Process. For the performance comparison of oxygen carrying abilities of Neo-PFC and a representative PFC emulsion, the oxidation states of cerebral tissues in substituted animals were measured by near-infrared spectrometry. After the 70% exchange transfusion of whole blood of rats by Neo-PFC and Fluosol-DA, fractional inspired oxygen (FiO2) was gradually decreased from 100% to 0%. As the control experiments, the blood was substituted by Krebs Ringer bicarbonate buffer containing 3% BSA. When the blood of rats was substituted by Neo-PFC, Cyt. ox., a terminal enzyme in mitochondrial respiratory chain maintained fully oxidized state with FiO2 values between 100 to 40%. By contrast, in the models substituted by Fluosol-DA and BSA-buffer. Cyt. ox. was gradually reduced with FiO2 values below 60% and 80%, respectively. This specific advantage of Neo-PFC was explained by its higher oxygen solubility in arterial blood. The novel PFC emulsion prepared by the new emulsifying technology is a potential basis for blood substitutes.

Virus inactivation in hemoglobin solution by heat treatment.

To increase the safety of stroma-free hemoglobin solution (SFH) as an artificial oxygen carrier source, we investigated the effect of heat treatment on virus inactivation in hemoglobin solution. The hemoglobin solution spiked with vesicular stomatitis virus (VSV) was treated at 60 degrees C for 1 hr under either an air or CO atmosphere. VSV was inactivated at >5.8 log10 and >6.0 log10 under the air and CO atmosphere, respectively. Although the methemoglobin rate increased after the heat treatment under the air atmosphere, no methemoglobin formation was observed by the treatment under the CO atmosphere. Isoelectric focusing analysis revealed the denaturation of hemoglobin after the heat treatment under the air, while hemoglobin banding was not altered in the carbonylated condition. Some protein bands other than hemoglobin were weakened or disappeared on SDS-PAGE after the heat treatment under both conditions. In addition, the hemoglobin concentration in the SFH was higher after the heat treatment than before the treatment. These findings indicate that the heat treatment under the CO atmosphere inactivates viruses without hemoglobin denaturation, and hence, this method is a promising approach to prepare a safer SFH as artificial oxygen carriers.

Recent developments in hemoglobin-based oxygen carriers--an update on clinical trials.

Considerable progress has been made in the development of the hemoglobin based oxygen carriers (HBOCs), with a number of products in the final stages of clinical development prior to licensing application. This follows many years of concentrated study. Although there are limitations to the clinical use of the currently studied HBOCs, there are a number of advantages that suggest that these products will have an important role in future clinical practice. It is anticipated that these products will be commercially available within two years.

Blood substitutes in surgery.

BACKGROUND: Despite increasing safety of blood supplies, and blood conservation strategies, the need for blood transfusion is increasing. Due to storage characteristics, blood is not always available when it is needed. AIMS: Review the necessity for an oxygen carrying blood substitute. Review the history of the compounds that may become blood substitutes, and briefly describe those in clinical trials. MATERIAL AND METHODS: Review of literature in the area of blood substitutes. RESULTS AND CONCLUSIONS: There is a need for oxygen carrying blood substitutes. Despite disappointments in recent clinical trials leading to withdraw of some compounds, there are several promising products nearing clinical approval.

A system establishment compatibility profiles for artificial oxygen carriers and other substances.

Worldwide, great efforts are being made to develop a clinically useful artificial oxygen carrier. Toxicological and immunological compatibility is generally tested using animal experiments but inflammatory parameters in particular show large species-specific differences. Therefore, we developed an in vitro system using human components to establish a compatibility profile of unknown compounds. The test system comprises induction of hemolysis, activation of complement (C3a), induction/suppression of cytokine production, influence on cell proliferation, direct toxicity on peripheral leukocytes, and phagocytosis of the material under test and of microbes. The test system will be described, along with results of various perfluorocarbon emulsions. When testing lecithin-based perfluorodecalin (PFD) emulsions, and comparing them to Pluronic-based PFD emulsions, we could show that Pluronic-based emulsions were virtually untoxic to peripheral human leukocytes. They neither inhibited cell proliferation nor caused any hemolysis, but caused mild to moderate inhibition of endotoxin-induced cytokine production. At the same time, lecithin-based PFD emulsion caused substantial cytotoxicity in phagocytic cells like monocytes (60-100% after 24 h incubation) and granulocytes (10-20% after 24 h incubation). They also suppressed endotoxin-induced cytokine production in monocytes to more than 98% and inhibited cell proliferation of an endothelial (ECV 304) and a monocytic cell line (MonoMac6) to more than 95%.