Optimizing the lyophilization of Lumbricus terrestris erythrocruorin.

Haemorrhagic shock is a leading cause of death worldwide. Blood transfusions can be used to treat patients suffering severe blood loss but donated red blood cells (RBCs) have several limitations that limit their availability and use. To solve the problems associated with donated RBCs, several acellular haemoglobin-based oxygen carriers (HBOCs) have been developed to restore the most important function of blood: oxygen transport. One promising HBOC is the naturally extracellular haemoglobin (i.e. erythrocruorin) of Lumbricus terrestris (LtEc). The goal of this study was to maximise the portability of LtEc by lyophilising it and then testing its stability at elevated temperatures. To prevent oxidation, several cryoprotectants were screened to determine the optimum formulation for lyophilisation that could minimise oxidation of the haem iron and maximise recovery. Furthermore, samples were also deoxygenated prior to storage to decrease auto-oxidation, while resuspension in a solution containing ascorbic acid was shown to partially reduce LtEc that had oxidised during storage (e.g. from 42% Fe3+ to 11% Fe3+). Analysis of the oxygen equilibria and size of the resuspended LtEc showed that the lyophilisation, storage, and resuspension processes did not affect the oxygen transport properties or the structure of the LtEc, even after 6 months of storage at 40 °C. Altogether, these efforts have yielded a shelf-stable LtEc powder that can be stored for long periods at high temperatures, but future animal studies will be necessary to prove that the resuspended product is a safe and effective oxygen transporter in vivo.

Experience with aortic arch inclusion technique using artificial blood vessel for type A aortic dissection: an application study.

BACKGROUND: This study aimed to elucidate the methodology and assess the efficacy of the aortic arch inclusion technique using an artificial blood vessel in managing acute type A aortic dissection (ATAAD). METHODS: We conducted a retrospective review of 18 patients (11 males and 7 females, average age: 56.2 ± 8.6 years) diagnosed with ATAAD who underwent total aortic arch replacement (TAAR) using an artificial vascular "inclusion" between June 2020 and October 2022. During the operation, deep hypothermic circulatory arrest (DHCA) and selective antegrade cerebral perfusion (ACP) of the right axillary artery were employed for brain protection. The 'inclusion' total aortic arch replacement and stented elephant trunk (SET) surgery were performed. RESULTS: Four patients underwent the Bentall procedure during the study, with one additional patient requiring coronary artery bypass grafting (CABG) due to significant involvement of the right coronary orifice. Three patients died during postoperative hospitalization. Other notable complications included two cases of postoperative renal failure necessitating continuous renal replacement therapy (CRRT), one case of postoperative double lower limb paraplegia, and one case of cerebral infarction resulting in unilateral impairment of the left upper limb. Eleven patients underwent computed tomography angiography (CTA) examinations of the aorta three months to one-year post-operation. The CTA results revealed thrombosis in the false lumen surrounding the aortic arch stent in seven patients and complete thrombosis of the false lumen around the descending aortic stent in eight patients. One patient had partial thrombosis of the false lumen around the descending aortic stent, and another patient's false lumen in the thoracic and abdominal aorta completely resolved after one year of follow-up. CONCLUSIONS: Incorporating vascular graft in aortic arch replacement simplifies the procedure and yields promising short-term outcomes. It achieves the aim of total arch replacement using a four-branch prosthetic graft. However, extensive sampling and thorough, prolonged follow-up observations are essential to fully evaluate the long-term results.

Toxic side-effects of diaspirin cross-linked human hemoglobin are attenuated by the apohemoglobin-haptoglobin complex.

Alpha-alpha diaspirin-crosslinked human hemoglobin (DCLHb or ααHb) was a promising early generation red blood cell (RBC) substitute. The DCLHb was developed through a collaborative effort between the United States Army and Baxter Healthcare. The core design feature underlying its development was chemical stabilization of the tetrameric structure of hemoglobin (Hb) to prevent Hb intravascular dimerization and extravasation. DCLHb was developed to resuscitate warfighters on the battlefield, who suffered from life-threatening blood loss. However, extensive research revealed toxic side effects associated with the use of DCLHb that contributed to high mortality rates in clinical trials. This study explores whether scavenging Hb and heme via the apohemoglobin-haptoglobin (apoHb-Hp) complex can reduce DCLHb associated toxicity. Awake Golden Syrian hamsters were equipped with a window chamber model to characterize the microcirculation. Each group was first infused with either Lactated Ringer's or apoHb-Hp followed by a hypovolemic infusion of 10% of the animal's blood volume of DCLHb. Our results indicated that animals pretreated with apoHb-Hb exhibited improved microhemodynamics vs the group pretreated with Lactated Ringer's. While systemic acute inflammation was observed regardless of the treatment group, apoHb-Hp pretreatment lessened those effects with a marked reduction in IL-6 levels in the heart and kidneys compared to the control group. Taken together, this study demonstrated that utilizing a Hb and heme scavenger protein complex significantly reduces the microvasculature effects of ααHb, paving the way for improved HBOC formulations. Future apoHb-Hp dose optimization studies may identify a dose that can completely neutralize DCLHb toxicity.

An optimized artificial blood feeding assay to study tick cuticle biology.

Ticks, ectoparasitic arachnids, are prominent disease vectors impacting both humans and animals. Their unique blood-feeding phase involves significant abdominal cuticle expansion, sharing certain similarities with insects. However, vital aspects, including the mechanisms of cuticle expansion, changes in cuticular protein composition, chitin synthesis, and cuticle function, remain poorly understood. Given that the cuticle expansion is crucial for complete engorgement of the ticks, addressing these knowledge gaps is essential. Traditional tick research involving live animal hosts has inherent limitations, such as ethical concerns and host response variability. Artificial membrane feeding systems provide an alternative approach, offering controlled experimental conditions and reduced ethical dilemmas. These systems enable precise monitoring of tick attachment, feeding parameters, and pathogen acquisition. Despite the existence of various methodologies for artificial tick-feeding systems, there is a pressing need to enhance their reproducibility and effectiveness. In this context, we introduce an improved tick-feeding system that incorporates adjustments related to factors like humidity, temperature, and blood-feeding duration. These refinements markedly boost tick engorgement rates, presenting a valuable tool for in-depth investigations into tick cuticle biology and facilitating studies on molting. This refined system allows for collecting feeding ticks at specific stages, supporting research on tick cuticle biology, and evaluating chemical agents' efficacy in the engorgement process.

[Rupture of Artificial Blood Vessel by a Sternal Wire:Report of a Case].

Formation of a pseudoaneurysm due to blood leakage from the anastomotic site of the vascular graft in large-diameter vessels is often seen, but formation of a pseudoaneurysm from the non-anastomotic site is extremely rare. A 68-year-old woman presented with a history of double valve replacement for combined valvular disease at 37 years old and hemiarch replacement for thoracic aortic dilatation at 65 years old. She visited the emergency room with a 2-week history of chest pain. Contrast-enhanced computed tomography (CT) revealed a 5-cm-diameter pseudoaneurysm and extravasation from the ascending aorta, so emergency surgery was performed. Around the ascending aorta area, we confirmed bleeding from a 5-mm dehiscence in the non-anastomotic part of the graft prosthesis, so hemostasis was performed with a cross-stitch mattress suture over a felt strip. Initially, the cause of the pseudoaneurysm was unknown, but re-examination of CT images from after the previous hemiarch replacement confirmed contact between the sternal wire and graft prosthesis. The wire was thus considered to have caused damage and bleeding. The patient was discharged from the hospital with a good postoperative course and is being followed-up in the outpatient department.

Recent advances in microfluidic technology of arterial thrombosis investigations.

Microfluidic technology has emerged as a powerful tool in studying arterial thrombosis, allowing researchers to construct artificial blood vessels and replicate the hemodynamics of blood flow. This technology has led to significant advancements in understanding thrombosis and platelet adhesion and aggregation. Microfluidic models have various types and functions, and by studying the fabrication methods and working principles of microfluidic chips, applicable methods can be selected according to specific needs. The rapid development of microfluidic integrated system and modular microfluidic system makes arterial thrombosis research more diversified and automated, but its standardization still needs to be solved urgently. One key advantage of microfluidic technology is the ability to precisely control fluid flow in microchannels and to analyze platelet behavior under different shear forces and flow rates. This allows researchers to study the physiological and pathological processes of blood flow, shedding light on the underlying mechanisms of arterial thrombosis. In conclusion, microfluidic technology has revolutionized the study of arterial thrombosis by enabling the construction of artificial blood vessels and accurately reproducing hemodynamics. In the future, microfluidics will place greater emphasis on versatility and automation, holding great promise for advancing antithrombotic therapeutic and prophylactic measures.

What is the context? To study the mechanism of arterial thrombosis, including the platelet adhesion and aggregation behavior and the coagulation process.Microfluidic technology is commonly used to study thrombosis. Microfluidic technology can simulate the real physiological environment on the microscopic scale in vitro, with high throughput, low cost, and fast speed.As an innovative experimental platform, microfluidic technology has made remarkable progress and has found applications in the fields of biology and medicine.What is new? This review summarizes the different fabrication methods of microfluidics and compares the advantages and disadvantages of these methods. Recent developments in microfluidic integrated systems and modular microfluidic systems have led to more diversified and automated microfluidic chips in the future.The different types and functions of microfluidic models are summarized. Platelet adhesion aggregation and coagulation processes, as well as arterial thrombus-related shear force changes and mechanical behaviors, were investigated by constructing artificial blood vessels and reproducing hemodynamics.Microfluidics can provide a basis for the development of personalized thrombosis treatment strategies. By analyzing the mechanism of action of existing drugs, using microfluidic technology for high-throughput screening of drugs and evaluating drug efficacy, more drug therapy possibilities can be developed.What is the impact?This review utilizes microfluidics to further advance the study of arterial thrombosis, and microfluidics is also expected to play a greater role in the biomedical field in the future.

[In searching for perfect blood substitute. Creation and application of perftorane]. / V poiskakh ideal'nogo krovezamenitelya. Sozdanie i primenenie perftorana.

The article is devoted to historiography of perfluorocarbons, as well as discoverers of perftorane and their discoveries. There would be no national priority in transfusiology without these discoveries. Perftorane is the only one of the world series of perfluorocarbon emulsion drugs that has passed all phases of clinical trials. Perftorane has been used in clinical medicine for 30 years.

Polymerized Human Hemoglobin-Based Oxygen Carrier Preserves Lung Allograft Function During Normothermic Ex Vivo Lung Perfusion.

Normothermic ex vivo lung perfusion (EVLP) can resuscitate marginal lung allografts to increase organs available for transplantation. During normothermic perfusion, cellular metabolism is more active compared with subnormothermic perfusion, creating a need for an oxygen (O 2 ) carrier in the perfusate. As an O 2 carrier, red blood cells (RBCs) are a scarce resource and are susceptible to hemolysis in perfusion circuits, thus releasing cell-free hemoglobin (Hb), which can extravasate into the tissue space, thus promoting scavenging of nitric oxide (NO) and oxidative tissue damage. Fortunately, polymerized human Hb (PolyhHb) represents a synthetic O 2 carrier with a larger molecular diameter compared with Hb, preventing extravasation, and limiting adverse reactions. In this study, a next-generation PolyhHb-based perfusate was compared to both RBC and asanguinous perfusates in a rat EVLP model. During EVLP, the pulmonary arterial pressure and pulmonary vascular resistance were both significantly higher in lungs perfused with RBCs, which is consistent with RBC hemolysis. Lungs perfused with PolyhHb demonstrated greater oxygenation than those perfused with RBCs. Post-EVLP analysis revealed that the PolyhHb perfusate elicited less cellular damage, extravasation, iron tissue deposition, and edema than either RBCs or colloid control. These results show promise for a next-generation PolyhHb to maintain lung function throughout EVLP.

Three-dimensional printing and decellularized-extracellular-matrix based methods for advances in artificial blood vessel fabrication: A review.

Blood vessels are the tubes through which blood flows and are divided into three types: millimeter-scale arteries, veins, and capillaries as well as micrometer-scale capillaries. Arteries and veins are the conduits that carry blood, while capillaries are where blood exchanges substances with tissues. Blood vessels are mainly composed of collagen fibers, elastic fibers, glycosaminoglycans and other macromolecular substances. There are about 19 feet of blood vessels per square inch of skin in the human body, which shows how important blood vessels are to the human body. Because cardiovascular disease and vascular trauma are common in the population, a great number of researches have been carried out in recent years by simulating the structures and functions of the person's own blood vessels to create different levels of tissue-engineered blood vessels that can replace damaged blood vessels in the human body. However, due to the lack of effective oxygen and nutrient delivery mechanisms, these tissue-engineered vessels have not been used clinically. Therefore, in order to achieve better vascularization of engineered vascular tissue, researchers have widely explored the design methods of vascular systems of various sizes. In the near future, these carefully designed and constructed tissue engineered blood vessels are expected to have practical clinical applications. Exploring how to form multi-scale vascular networks and improve their compatibility with the host vascular system will be very beneficial in achieving this goal. Among them, 3D printing has the advantages of high precision and design flexibility, and the decellularized matrix retains active ingredients such as collagen, elastin, and glycosaminoglycan, while removing the immunogenic substance DNA. In this review, technologies and advances in 3D printing and decellularization-based artificial blood vessel manufacturing methods are systematically discussed. Recent examples of vascular systems designed are introduced in details, the main problems and challenges in the clinical application of vascular tissue restriction are discussed and pointed out, and the future development trends in the field of tissue engineered blood vessels are also prospected.

Programmable adhesion and morphing of protein hydrogels for underwater robots.

Soft robots capable of efficiently implementing tasks in fluid-immersed environments hold great promise for diverse applications. However, it remains challenging to achieve robotization that relies on dynamic underwater adhesion and morphing capability. Here we propose the construction of such robots with designer protein materials. Firstly, a resilin-like protein is complexed with polyoxometalate anions to form hydrogels that can rapidly switch between soft adhesive and stiff non-adhesive states in aqueous environments in response to small temperature variation. To realize remote control over dynamic adhesion and morphing, Fe3O4 nanoparticles are then integrated into the hydrogels to form soft robots with photothermal and magnetic responsiveness. These robots are demonstrated to undertake complex tasks including repairing artificial blood vessel, capturing and delivering multiple cargoes in water under cooperative control of infrared light and magnetic field. These findings pave an avenue for the creation of protein-based underwater robots with on-demand functionalities.

Synthesis of bioactive hemoglobin-based oxygen carrier nanoparticles via metal-phenolic complexation.

The transfusion of donor red blood cells (RBCs) is seriously hampered by important drawbacks that include limited availability and portability, the requirement of being stored in refrigerated conditions, a short shelf life or the need for RBC group typing and crossmatching. Thus, hemoglobin (Hb)-based oxygen (O2) carriers (HBOCs) which make use of the main component of RBCs and the responsible protein for O2 transport, hold a lot of promise in modern transfusion and emergency medicine. Despite the great progress achieved, it is still difficult to create HBOCs with a high Hb content to attain the high O2 demands of our body. Herein a metal-phenolic self-assembly approach that can be conducted in water and in one step to prepare nanoparticles (NPs) fully made of Hb (Hb-NPs) is presented. In particular, by combining Hb with polyethylene glycol, tannic acid (TA) and manganese ions, spherical Hb-NPs with a uniform size around 350-525 nm are obtained. The functionality of the Hb-NPs is preserved as shown by their ability to bind and release O2 over multiple rounds. The binding mechanism of TA and Hb is thoroughly investigated by UV-vis absorption and fluorescence spectroscopy. The binding site number, apparent binding constant at two different temperatures and the corresponding thermodynamic parameters are identified. The results demonstrate that the TA-Hb interaction takes place through a static mechanism in a spontaneous process as shown by the decrease in Gibbs free energy. The associated increase in entropy suggests that the TA-Hb binding is dominated by hydrophobic interactions.

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.

Evaluation of "Caserotek" a low cost and effective artificial blood-feeding device for mosquitoes.

Entomological research studies on mosquito vector biology, vector competence, insecticide resistance, dispersal, and survival (using mark-release-recapture techniques) often rely on laboratory-reared mosquito colonies to produce large numbers of consistently reared, aged, and sized mosquitoes. We developed a low-cost blood feeding apparatus that supports temperatures consistent with warm blooded animals, using commonly available materials found in low resource environments. We compare our system ("Caserotek") to Hemotek and glass/membrane feeding methods. Two experiments were conducted with Aedes aegypti (Linnaeus 1762) and one with Anopheles darlingi (Root 1926) (Diptera: Culicidae); 3 replicates were conducted for each experiment. Aedes aegypti female mosquitoes were provided chicken blood once per week for 30 min (Experiment #1) for 14 days or 1 hour (Experiment #2) for 21 days. Anopheles darlingi were fed once for 1 hour (Experiment #3). Blood-feeding rates, survival rates, and egg production were calculated across replicates. Caserotek had a significantly higher 30-min engorgement rate (91.1%) than Hemotek (47.7%), and the glass feeder (29.3%) whereas for 1-hour feeding, Hemotek had a significantly lower engorgement rate than either of the other two devices (78% versus 91%). Thirty-day survival was similar among the feeding devices, ranging from 86% to 99%. Mean egg production was highest for the Caserotek feeder (32 eggs per female) compared to the glass feeder and Hemotek device (21-22 eggs per female). Our new artificial feeding system had significantly higher blood feeding rates than for more expensive artificial systems and was equivalent to other fitness parameters. Caserotek only requires the ability to boil water to maintain blood temperatures using a Styrofoam liner. It can be easily scaled up to large production facilities and used under austere conditions.

Perfluorocarbons in Research and Clinical Practice: A Narrative Review.

Perfluorocarbons (PFCs) are organic liquids derived from hydrocarbons in which some of the hydrogen atoms have been replaced by fluorine atoms. They are chemically and biologically inert substances with a good safety profile. They are stable at room temperature, easy to store, and immiscible in water. Perfluorocarbons have been studied in biomedical research since 1960 for their unique properties as oxygen carriers. In particular, PFCs have been used for liquid ventilation in unusual environments such as deep-sea diving and simulations of zero gravity, and more recently for drug delivery and diagnostic imaging. Additionally, when delivered as emulsions, PFCs have been used as red blood cell substitutes. This narrative review will discuss the multifaceted utilization of PFCs in therapeutics, diagnostics, and research. We will specifically emphasize the potential role of PFCs as red blood cell substitutes, as airway mechanotransducers during artificial placenta procedures, as a means to improve donor organ perfusion during the ex vivo assessment, and as an adjunct in cancer therapies because of their ability to reduce local tissue hypoxia.

Research Progress in Oxygen Carrier Design and Application.

Ischemia or hypoxia can lead to pathological changes in the metabolism and function of tissues and then lead to various diseases. Timely and effective blood resuscitation or improvement of hypoxia is very important for the treatment of diseases. However, there is a need to develop stable, nontoxic, and immunologically inert oxygen carriers due to limitations such as blood shortages, different blood types, and the risk of transmitting infections. With the development of various technologies, oxygen carriers based on hemoglobin and perfluorocarbon have been widely studied in recent years. This paper reviews the development and application of hemoglobin and perfluorocarbon oxygen carriers. The design of oxygen carriers was analyzed, and their application as blood substitutes or oxygen carriers in various hypoxic diseases was discussed. Finally, the characteristics and future research of ideal oxygen carriers were prospected to provide reference for follow-up research.

Improving the Performance of Poly(caprolactone)-Cellulose Acetate-Tannic Acid Tubular Scaffolds by Mussel-Inspired Coating.

Small-diameter artificial blood vessels are increasingly being used in clinical practice. However, these vessels are prone to thrombus, and it is necessary to improve blood compatibility. Surface coating is one of the commonly used methods in this regard. Inspired by the biomimicry of mussels, the use of deposition technology to obtain coating coverage on the surface of fibers has significantly piqued the interest of researchers recently. In this study, tubular scaffolds consisting of a composite of poly(caprolactone), cellulose acetate, and tannic acid (TA) were electrospun, and then the scaffolds were treated with different Fe(III) solutions (iron(III) chloride hexahydrate (FeCl3'6H2O)) to obtain four tubular scaffolds: F0, F5, F15, and F45. According to scanning electron microscopy (SEM) and field emission-SEM results, TA/Fe(III) complex is coated on the fiber of the scaffold after post-treatment; the fiber surface morphology changes with different Fe(III) concentrations. This provides designability to the performance of tubular scaffolds. The tensile strength of the F5 tubular scaffold (3.33 MPa) is higher than that of F45 (3.14 MPa), while the strain (83.9%) of the F45 tubular stent was 2.26 times that of the F5 (37.2%). In addition, cytotoxicity and antithrombotic performance were evaluated. The test results show that surface TA/Fe(III) coating treatment can affect the cytotoxicity and anticoagulation performance of the scaffold surface. The biomimetic TA/Fe(III) coating of mussels used in this study improves the performance of artificial blood vessels.

PLCL-TPU bi-layered artificial blood vessel with compliance matching to host vessel.

Compliance mismatch between the artificial blood vessel and the host vessel leads to abnormal hemodynamics and is a major mechanical trigger of intimal hyperplasia. Efforts have been made to achieve higher compliance of artificial blood vessels. However, the preparation of artificial blood vessels with compliance matching to host vessels has not been realized. A bi-layered artificial blood vessel was successfully prepared by dip-coating and electrospinning composite method using poly(L-Lactide-co-caprolactone) (PLCL) and thermoplastic poly(ether urethane) (TPU). In the case of a certain wall thickness (200 µm), thickness ratios of the PLCL inner layer (dip-coating method) and TPU outer layer (electrospinning method) were controlled at 0:1, 1:9, 3:7, 5:5, 7:3, and 1:0 respectively and the compliance, radial tensile properties, burst pressure, and suture retention strength were investigated. Results showed compliance value of the artificial blood vessel decreased with the increase of the thickness ratio, which suggested the compliance of the bi-layered artificial blood vessel can be regulated by adjusting the ratio of the inner and outer layer thicknesses. In the six different artificial blood vessels, the one with thickness ratio of 1:9 not only had high compliance (8.768 ± 0.393%/100 mmHg) but also can guarantee the other mechanical properties, such as the radial breaking strength (6.333 ± 0.689 N/mm), burst pressure (534.473 ± 20.899 mmHg), and suture retention strength (300.773 ± 9.351 cN). The proposed artificial blood vessel preparation method is expected to achieve compliance matching with the host vessel. It is beneficial for eliminating abnormal hemodynamics and reducing intimal hyperplasia.

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.

The artificial oxygen carrier erythrocruorin-characteristics and potential significance in medicine.

The diminishing supply and increasing costs of donated blood have motivated research into novel hemoglobin-based oxygen carriers (HBOCs) that can serve as red blood cell (RBC) substitutes. HBOCs are versatile agents that can be used in the treatment of hemorrhagic shock. However, many of the RBC substitutes that are based on mammalian hemoglobins have presented key limitations such as instability and toxicity. In contrast, erythrocruorins (Ecs) are other types of HBOCs that may not suffer these disadvantages. Ecs are giant metalloproteins found in annelids, crustaceans, and some other invertebrates. Thus far, the Ecs of Lumbricus terrestris (LtEc) and Arenicola marina (AmEc) are the most thoroughly studied. Based on data from preclinical transfusion studies, it was found that these compounds not only efficiently transport oxygen and have anti-inflammatory properties, but also can be modified to further increase their effectiveness. This literature review focuses on the structure, properties, and application of Ecs, as well as their advantages over other HBOCs. Development of methods for both the stabilization and purification of erythrocruorin could confer to enhanced access to artificial blood resources.

Alginate/xanthan gum hydrogels as forensic blood substitutes for bloodstain formation and analysis.

Understanding the behaviour of human blood outside of the body has important implications in forensic research, especially related to bloodstain pattern analysis (BPA). The design of forensic blood substitutes (FBSs) can provide many advantages, including the incorporation of multiple physiological components for use as safe and reliable materials for forensic applications. In this work, we present the design of synthetic alginate and xanthan gum-based hydrogels that contain electrosprayed microparticles (MPs) with and without crosslinked DNA. In addition to the MPs, the alginate/xanthan gum FBS materials include fillers to alter the physical appearance and fluid properties of the material. The optimized FBS consisted of alginate (1% w/v) and xanthan gum (5.0 × 10-3% w/v), 2 mM CaCl2, ferric citrate (0.5% w/v), magnesium silicate (0.25% w/v), Allura Red dye (2% w/v), 0.025% v/v Tween 20 and 9.5% v/v MPs. The FBS was tested in passive dripping experiments relevant to BPA scenarios at various impact angles. The spreading ratio (Ds/D0) was determined for 90° stains made on a paper surface and compared to bovine blood where the FBS was shown to simulate accurate and predictable spreading behaviour. In addition, we simulated other common BPA scenarios (e.g., impact patterns) and evidence processing potential. The FBS could be swabbed, and the DNA could be extracted, amplified, and genotyped analogous to human blood evidence. A stability test was also conducted which revealed a shelf-life of over 4 weeks where the material remains relevant to human blood at physiological temperature.