PEG-conjugated bovine haemoglobin enhances efficiency of chemotherapeutic agent doxorubicin with alleviating DOX-induced splenocardiac toxicity in the breast cancer

Doxorubicin (DOX) is an effective chemotherapeutic agent widely used for cancer treatment. However, hypoxia in tumour tissue and obvious adverse effects particularly cardiotoxicity restricts the clinical usage of DOX. Our study is based on the co-administration of haemoglobin-based oxygen carriers (HBOCs) and DOX in a breast cancer model to investigate HBOCs' ability to enhance chemotherapeutic effectiveness and its capabilities to alleviate the side effects induced by DOX. In an in-vitro study, the results suggested the cytotoxicity of DOX was significantly improved when combined with HBOCs in a hypoxic environment, and produced more γ-H2AX indicating higher DNA damage than free DOX did. Compared with administration of free DOX, combined therapy exhibited a stronger tumour suppressive effect in an in-vivo study. Further mechanism studies showed that the expression of various proteins such as hypoxia-inducible factor-1α (HIF-1α), CD31, CD34, and vascular endothelial growth factor (VEGF) in tumour tissues was also significantly reduced in the combined treatment group. In addition, HBOCs can significantly reduce the splenocardiac toxicity induced by DOX, according to the results of the haematoxylin and eosin (H&E) staining and histological investigation. This study suggested that PEG-conjugated bovine haemoglobin may not only reduce the hypoxia in tumours and increase the efficiency of chemotherapeutic agent DOX, but also alleviate the irreversible heart toxicity caused by DOX-inducted splenocardiac dysregulation.

The Preliminary Study on Preparation Technology of PolyHb-SOD-CAT-CA - The Effects of Different Extractants

Aim： As a new generation of blood substitutes, polyHb-SOD-CAT-CA has shown good application prospects in the existing research and explorations, resulting in the necessity of research on its process and preparation technology for future development.

INTRODUCTION

To explore the alternative to extractants for the preparation technology of polyHb-SOD-CAT-CA derived both from bovine blood and human cord blood, compared to the toluene currently used in the existing studies, several organic solvents, including n-hexane and ethyl ether, were investigated during the polyHb-SOC-CAT-CA preparation process.

METHODS

During the technological process, the effects of investigated organic extractants on the properties and stability of hemoglobin and enzymes, including SOD, CAT and CA, were investigated by monitoring the property indexes of macromolecules, including Hb concentrations, MetHb contents, molecular weight distribution, oxygen affinity of Hb, enzymes activities, and so on.

RESULTS

Among the investigated experimental groups, the results, including the Hb recoveries, MetHb contents, oxygen affinity, the molecular weight distribution of obtained complex, and enzyme activity, presented to be the best in n-hexane groups, followed by those in toluene groups, and these results in ether groups showed to be the worst. Meanwhile, during the preparation process, both for bovine and human cord derivatives, the changing of properties indexes of Hb and enzymes investigated demonstrated similar declining trends on the whole, and the oxygen-carrying properties and enzyme activities showed to be in the effective range.

CONCLUSION

Among the investigated organic extractants, both for preparation of bovine and human cord-derived polyHb-SOD-CAT-CA complex, n-hexane indicated to have much less negative influence on the properties and stability of Hb and enzyme molecules, including SOD, CAT, and CA. Moreover, the obtained human cord blood polyHb-SOD-CAT-CA also showed effective oxygen-carrying properties and enzyme activities, suggesting the promising application prospects of polyHb-SOD-CAT-CA and the new generation HBOC products in the future.

Protective effect and mechanism of low P50 haemoglobin oxygen carrier on isolated rat heart

The protection of the isolated heart is very important in heart transplantation surgery, meanwhile, the ischaemia/reperfusion (I/R) of the isolated heart is the main cause of its damage. A timely supply of oxygen can significantly improve the prevention of myocardial ischaemia, however, the cardioprotective solution does not have an oxygen supply function. Haemoglobin Based on Oxygen Carriers (HBOCs) is a kind of nano-oxygen drug, which can effectively and timely supply oxygen to hypoxic organs and tissues. However, the oxygen-carrying and releasing capacity (P50) is different with different HBOCs. The aim of our study was to investigate whether STS (a kind of cardioprotective solution, St Thomas Solution) +different P50 HBOCs provide superior myocardial protection and decrease myocardial injury compared to only STS in rats Langendorff isolated heart perfusion model. The results showed that STS + HBOCs can improve cardiac function at 37 °C for 35 min and 120 min, and reduce myocardial infarctions, pathological changes, and apoptosis of cardiomyocytes, and the STS + low P50 HBOCs is more effective than the other two higher P50 HBOCs. We further demonstrated the outstanding protective effect of STS + low P50 HBOCs on cardiac function, reducing myocardial infarctions and apoptosis of cardiomyocytes in rat Langendorff isolated heart perfusion model.

Production of functional human fetal hemoglobin in Nicotiana benthamiana for development of hemoglobin-based oxygen carriers

Hemoglobin-based oxygen carriers have long been pursued to meet clinical needs by using native hemoglobin (Hb) from human or animal blood, or recombinantly produced Hb, but the development has been impeded by safety and toxicity issues. Herewith we report the successful production of human fetal hemoglobin (HbF) in Nicotiana benthamiana through Agrobacterium tumefaciens-mediated transient expression. HbF is a heterotetrameric protein composed of two identical α- and two identical γ-subunits, held together by hydrophobic interactions, hydrogen bonds, and salt bridges. In our study, the α- and γ-subunits of HbF were fused in order to stabilize the α-subunits and facilitate balanced expression of α- and γ-subunits in N. benthamiana. Efficient extraction and purification methods enabled production of the recombinantly fused endotoxin-free HbF (rfHbF) in high quantity and quality. The transiently expressed rfHbF protein was identified by SDS-PAGE, Western blot and liquid chromatography-tandem mass spectrometry analyses. The purified rfHbF possessed structural and functional properties similar to native HbF, which were confirmed by biophysical, biochemical, and in vivo animal studies. The results demonstrate a high potential of plant expression systems in producing Hb products for use as blood substitutes.

Polydopamine-based surface modification of hemoglobin particles for stability enhancement of oxygen carriers

Templated assembly techniques have been extensively used to develop various types of hemoglobin (Hb) loaded particles with improved performance. However, several instability issues must still be solved, including Hb exposure, enhanced Hb auto-oxidation, and the relatively weak binding of Hb to cross-linkers. Herein, to meet the stability requirements for novel hemoglobin-based oxygen carriers (HBOCs), hemoglobin-polydopamine particles (Hb-PDA) were fabricated using a mild process that combines the co-precipitation of Hb and an inorganic template with the spontaneous adhesion of PDA. The Hb-PDA showed uniform size distribution, chemical integrity of both Hb and PDA, high biocompatibility, and robust oxygen delivery. Our results demonstrated that the use of polydopamine as a biocompatible coating material reduced Hb leakage from the particles under both static and flow conditions, thus mitigating the toxicity associated with free Hb and strengthening the stability of Hb particles. In addition, Hb-PDA reduced HUVEC (Human Umbilical Vein Cells) oxidative injury and scavenged 85% of the available hydroxyl radicals, exhibiting its potential to act as an antioxidant for encapsulated Hb. Hb-PDA therefore shows significant promise as a cell-like structurally and functionally stable HBOCs.

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.

Kinetic studies on oxygen releasing of HBOC and red blood cells as fluids and factors affecting the process

Red blood cells (RBCs) possess intact cyto-architectures while haemoglobin (Hb) is a cell-free, homogeneous solution. Both RBCs and Hb are generalized oxygen carriers. In this paper, kinetic studies on oxygen-releasing of high concentration of Hb and RBCs under various conditions were carried out regarding Hb and RBCs as fluids. Among them, Hb under specific conditions was seen as the simplest Hb-based oxygen carrier (HBOC), Also, factors affecting the oxygen releasing of Hb and RBCs, including osmotic pressure, viscosity and allosteric agent, have been well studied. Analysis of the results from the measurement above showed that kinetics of oxygen releasing of either pure Hb or the simplest HBOCs was obviously different from that of RBCs. The oxygen-releasing time of Hb was shorter and the oxygen-releasing rates of Hb were quicker than those of RBCs under various conditions. Therefore, as fluids, only by changing the milieus it exists in, Hb could not achieve the expected oxygen-releasing effect on the microcirculation so well as RBCs do in the same system, irrespective of the interaction between the fluids and blood vessels. Furthermore, kinetic properties of HBOCs must be considered and matched with those of RBCs in the study of HBOCs.

Application of HBOCs electrophoretic method to detect a new blood substitute derived from the giant extracellular haemoglobin of lugworm

Manipulation of blood and blood components is prohibited in sports by the World Anti-Doping Agency (WADA). This includes the use of blood substitutes to increase oxygen transport, like haemoglobin-based oxygen carriers (HBOCs), which are compounds derived from haemoglobin. Despite their medical interest, the first generation of HBOCs had serious adverse effects and was abandoned. However, new studies are now exploiting the properties of marine worm haemoglobins, which circulate as giant extracellular complexes with high oxygen-binding capacities. HEMOXYCarrier® (HC), developed by Hemarina, is one of the most advanced and promising HBOCs, and HC may become a tempting doping tool for athletes in the future. Here, HC detection in plasma/serum was evaluated with the method used to detect the first HBOCs, based on electrophoresis and heme peroxidase properties. An HC-derived product was identified in human plasma up to 72 h after in vitro incubation at 37 °C. HC degradation also induced methemalbumin formation. After injecting HC at the effective dose of 200 mg/kg into mice, the HC-derived product was detected only for a few hours and no accumulation of methemalbumin was observed. Due to this limited detection window in vivo, measuring specific worm globin degradation products by mass spectrometry might be an alternative for future anti-doping analyses. Copyright © 2016 John Wiley & Sons, Ltd.