Small change in blood acidity could prove detrimental to kidney disease patients

A University of Manchester scientist has discovered that very small changes in the level of acidity in blood may have a detrimental impact on the health of patients with kidney disease.

Chronic Kidney Disease (CKD) is common in the UK.  It is estimated that about one in five men and one in four women between the ages of 65 and 74 has some degree of CKD. The leading single cause of CKD is diabetes which is increasing so it’s expected that more patients will be diagnosed with CKD in the future.

Dr Donald Ward from the Faculty of Life Sciences has been studying the impact of kidney disease on the body. He has found that very small changes in the pH (acidity) level in the blood prevents the body from being able to accurately monitor calcium levels. This leads to too much of the hormone PTH being released which is likely to lead to a greater risk of calcium and phosphate from the bone damaging the arteries. This often proves fatal to patients with CKD. His research has been published in the Journal of the American Society of Nephrology. 

Dr Donald Ward

He says: “It was not realised before that the blood pH changes we see in patients with kidney disease can have an impact on their ability to monitor blood calcium levels. My research has demonstrated that the effect of those changes may be more significant than previously thought and thus might need to be looked at more carefully by clinicians.”

Dr Ward’s research focussed on the high level of parathyroid hormone (PTH) in patients suffering from CKD. This causes the body to release calcium and phosphate from the bones which can then damage their blood vessels. 

Dr Ward explains why this is so harmful: “The diseased kidneys prevent the body getting rid of both excess phosphate and excess acidity. So if that acidity also causes the body to release more PTH then this could compound the problem by releasing further phosphate from the bone. This vicious circle might accelerate the potentially fatal calcification of the arteries.” 

He continues: “What is so important about this research is that we have demonstrated that changes in PTH release can be prompted by very small changes in blood pH level. Before, it was assumed that only a larger change in acidity would cause problems for patients.”

The research was funded by Kidney Research UK. Elaine Davies, Director of Research Operations, from the charity says: “Donald’s work has used novel pharmacological and molecular tools in generating these new findings which increase our knowledge about the complex balance that clinicians need to consider when treating patients with CKD.”

Dr Ward is hoping to take his research to the next step, testing for therapeutic targets that could lead to better treatments for CKD.

Source: Manchester University

Understanding, improving body's fight against pathogens

Significant reductions in the number of plasma cells in the spleen and bone marrow were observed in the absence of DOK3. Each dot in the figure represents one plasma cell detected. Credit: Image courtesy of A*Star Agency for Science, Technology and Research

Scientists from A*STAR's Bioprocessing Technology Institute (BTI) have uncovered the crucial role of two signalling molecules, DOK3 and SHP1, in the development and production of plasma cells. These discoveries, published in two journals PNAS and Nature Communications, advance the understanding of plasma cells and the antibody response, and may lead to optimisation of vaccine development and improved treatment for patients with autoimmune diseases such as lupus and tumours such as multiple myeloma.

While they exist in small populations in humans, the large amounts of antibodies secreted by plasma cells make them key to the body's immune system and its ability to defend itself against pathogens, such as bacteria and viruses. Proper maintenance of a pool of plasma cells is also critical for the establishment of lifelong immunity elicited by vaccination.

Dysregulation of plasma cell production and maintenance could lead to autoimmune diseases and multiple myeloma. Autoimmune diseases occur when the immune system does not distinguish between healthy tissue and antigens, which are found in pathogens. This results in expansion of plasma cells which produce excessive amounts of antibodies leading to destruction of one's own healthy tissue. The discoveries by scientists in BTI's Immunology Group have improved understanding of the mechanism by which plasma cells are developed from a major class of white blood cells called B cells.

For the first time, the molecule DOK3 was found to play an important role in formation of plasma cells. While calcium signalling typically controls a wide range of cellular processes that allow cells to adapt to changing environments, it was found to inhibit the expression of the membrane proteins essential for plasma cell formation. These membrane proteins include PDL1 and PDL2, and represent some of the key targets for the development of immunotherapy by pharmaceutical companies. DOK3 was able to promote the production of plasma cells by reducing the effects of calcium signalling on these membrane proteins. The absence of DOK3 would thus result in defective plasma cell formation.

In another study, BTI scientists discovered the importance of SHP1 signalling to the long term survival of plasma cells. While the molecule SHP1 has a proven role in prevention of autoimmune diseases, it was found that the absence of SHP1 would result in the failure of plasma cells to migrate from the spleen where they are generated to the bone marrow, a survival niche where they are able to survive for much longer periods. This could result in a reduction of the body's immune response and thus, an increased susceptibility to infections and diseases. The scientists in this study also successfully rectified the defective immune response caused by an absence of SHP1 by applying antibody injections, which might advance the development of therapeutics. On the other hand, targeting SHP1 might be a strategy to treat multiple myeloma where the accumulation of cancerous plasma cells in the bone marrow survival niches is undesirable.

Findings hold potential for improved treatment

The discovery of these new targets for modulating the antibody response allows the development of novel therapeutic strategies for patients with autoimmune diseases and cancer.Understanding the mechanism that governs plasma cell differentiation is also critical for the optimal design of vaccines and adjuvants, which are added to vaccines to boost the body's immune response.

Prof Lam Kong Peng, Executive Director of BTI, said, "These findings allow better understanding of plasma cells and their role in the immune system. The identification of these targets not only paves the way for development of therapeutics for those with autoimmune diseases and multiple myeloma, but also impacts the development of immunological agents for combating infections."

Source: A*Star Agency for Science, Technology and Research

Shape of things to come in platelet mimicry

By mimicking the shape, size, flexibility and surface chemistry of real platelets, artificial platelets are pushed out of the main blood flow to vessel walls. There, the surface chemistry enables them to anchor on damaged cells and induce faster clotting at the site. Credit: Anirban Sen Gupta

Artificial platelet mimics developed by a research team from Case Western Reserve University and University of California, Santa Barbara, are able to halt bleeding in mouse models 65 percent faster than nature can on its own.

For the first time, the researchers have been able to integratively mimic the shape, size, flexibility and surface chemistry of real blood platelets on albumin-based particle platforms. The researchers believe these four design factors together are important in inducing clots to form faster selectively at vascular injury sites while preventing harmful clots from forming indiscriminately elsewhere in the body.

The new technology, reported in the journal ACS Nano, is aimed at stemming bleeding in patients suffering from traumatic injury, undergoing surgeries or suffering clotting disorders from platelet defects or a lack of platelets. Further, the technology may be used to deliver drugs to target sites in patients suffering atherosclerosis, thrombosis or other platelet-involved pathologic conditions.

Anirban Sen Gupta, an associate professor of biomedical engineering at Case Western Reserve, previously designed peptide-based surface chemistries that mimic the clot-relevant activities of real platelets. Building on this work, Sen Gupta now focuses on incorporating morphological and mechanical cues that are naturally present in platelets to further refine the design.

"Morphological and mechanical factors influence the margination of natural platelets to the blood vessel wall, and only when they are near the wall can the critical clot-promoting chemical interactions take place," he said.

These natural cues motivated Sen Gupta to team up with Samir Mitragotri, a professor of chemical engineering at UC Santa Barbara, whose laboratory has recently developed albumin-based technologies to make particles that mimic the geometry and mechanical properties of red blood cells and platelets.

Together, the team has developed artificial platelet-like nanoparticles (PLNs) that combine morphological, mechanical and surface chemical properties of natural platelets.

The researchers believe this refined design will be able to simulate natural platelet's ability to collide effectively with larger and softer red blood cells in systemic blood flow. The collisions cause margination -- pushing the platelets out of the main flow and closer to the blood vessel wall -- increasing the probability of interacting with an injury site.

The surface coatings enable the artificial platelets to anchor to injury-site-specific proteins, von Willebrand Factor and collagen, while inducing the natural and artificial platelets to aggregate faster at the injury site.

Testing in mouse models showed that intravenous injection of these artificial platelets formed clots at the site of injury three times faster than natural platelets alone in control mice.

The ability to interact selectively with injury site proteins, as well as the ability to remain mechanically flexible like natural platelets, enables these artificial platelets to safely ride through the smallest of blood vessels without causing unwanted clots.

Albumin, a protein found in blood serum and eggs, is already used with cancer drugs and considered a safe material. Artificial platelets that don't become involved in a clot and continue to circulate are metabolized within one to two days.

The researchers believe the new artificial platelet design may be even more effective in larger volume blood flows where margination to the blood vessel wall is more prominent. They expect to soon begin testing those capabilities.

This research was previously funded by American Heart Association and is currently funded by National Institutes of Health.

In addition to stemming bleeding, Sen Gupta believes the technology could also be useful in delivering clot-busting medicines directly to clots, to treat heart attack or stroke without having to systemically suspend the body's coagulation mechanism. The artificial platelets may also be used to deliver cancer medicines to metastatic tumors that have high platelet interactions. Sen Gupta is seeking grants to pursue that work.

Source: Case Western Reserve University

Bio-inspired bleeding control: Synthesized platelet-like nanoparticles created

Artist's rendering of synthetic platelets. Credit: Peter Allen illustration

Stanching the free flow of blood from an injury remains a holy grail of clinical medicine. Controlling blood flow is a primary concern and first line of defense for patients and medical staff in many situations, from traumatic injury to illness to surgery. If control is not established within the first few minutes of a hemorrhage, further treatment and healing are impossible.

At UC Santa Barbara, researchers in the Department of Chemical Engineering and at Center for Bioengineering (CBE) have turned to the human body's own mechanisms for inspiration in dealing with the necessary and complicated process of coagulation. By creating nanoparticles that mimic the shape, flexibility and surface biology of the body's own platelets, they are able to accelerate natural healing processes while opening the door to therapies and treatments that can be customized to specific patient needs.

"This is a significant milestone in the development of synthetic platelets, as well as in targeted drug delivery," said Samir Mitragotri, CBE director, who specializes in targeted therapy technologies. Results of the researchers' findings appear in the current issue of the journal ACS Nano.

The process of coagulation is familiar to anyone who has suffered even the most minor of injuries, such as a scrape or paper cut. Blood rushes to the site of the injury, and within minutes the flow stops as a plug forms at the site. The tissue beneath and around the plug works to knit itself back together and eventually the plug disappears.

But what we don't see is the coagulation cascade, the series of signals and other factors that promote the clotting of blood and enable the transition between a free-flowing fluid at the site and a viscous substance that brings healing factors to the injury. Coagulation is actually a choreography of various substances, among the most important of which are platelets, the blood component that accumulates at the site of the wound to form the initial plug.

"While these platelets flow in our blood, they're relatively inert," said graduate student researcher Aaron Anselmo, lead author of the paper. As soon as an injury occurs, however, the platelets, because of the physics of their shape and their response to chemical stimuli, move from the main flow to the side of the blood vessel wall and congregate, binding to the site of the injury and to each other. As they do so, the platelets release chemicals that "call" other platelets to the site, eventually plugging the wound.

But what happens when the injury is too severe, or the patient is on anti-coagulation medication, or is otherwise impaired in his or her ability to form a clot, even for a modest or minor injury?

That's where platelet-like nanoparticles (PLNs) come in. These tiny, platelet-shaped 

particles that behave just like their human counterparts can be added to the blood flow to supply or augment the patient's own natural platelet supply, stemming the flow of blood and initiating the healing process, while allowing physicians and other caregivers to begin or continue the necessary treatment. Emergency situations can be brought under control faster, injuries can heal more quickly and patients can recover with fewer complications.

"We were actually able to render a 65 percent decrease in bleeding time compared to no treatment," said Anselmo.

According to Mitragotri, the key lies in the PLNs' mimicry of the real thing. By imitating the shape and flexibility of natural platelets, PLNs can also flow to the injury site and congregate there. With surfaces functionalized with the same biochemical motifs found in their human counterparts, these PLNs also can summon other platelets to the site and bind to them, increasing the chances of forming that essential plug. In addition, and very importantly, these platelets are engineered to dissolve into the blood after their usefulness has run out. This minimizes complications that can arise from emergency hemostatic procedures.

"The thing about hemostatic agents is that you have to intervene to the right extent," said Mitragotri. "If you do too much, you cause problems. If you do too little, you cause problems."

These synthetic platelets also let the researchers improve on nature. According to Anselmo's investigations, for the same surface properties and shape, nanoscale particles can perform even better than micron-size platelets. Additionally, this technology allows for customization of the particles with other therapeutic substances -- medications, therapies and such -- that patients with specific conditions might need.

"This technology could address a plethora of clinical challenges," said Dr. Scott Hammond, director of UCSB's Translational Medicine Research Laboratories. "One of the biggest challenges in clinical medicine right now -- which also costs a lot of money -- is that we're living longer and people are more likely to end up on blood thinners. When an elderly patient presents at a clinic, it's a huge challenge because you have no idea what their history is and you might need an intervention."

With optimizable PLNs, physicians would be able to strike a finer balance between anticoagulant therapy and wound healing in older patients, by using nanoparticles that can target where clots are forming without triggering unwanted bleeding. In other applications, bloodborne pathogens and other infectious agents could be minimized with antibiotic-carrying nanoparticles. Particles could be made to fulfill certain requirements to travel to certain parts of the body -- across the blood-brain barrier, for instance -- for better diagnostics and truly targeted therapies.

Additionally, according to the researchers, these synthetic platelets cost relatively less, and have a longer shelf life than do human platelets -- a benefit in times of widespread emergency or disaster, when the need for these blood components is at its highest and the ability to store them onsite is essential.

Further research into PLNs will involve investigations to see how well the technology and synthesis can scale up, as well as assessments into the more practical matters involved in translating the technology from the lab to the clinic, such as manufacturing, storage, sterility and stability as well as pre-clinical and clinical testing.

Source: University of California - Santa Barbara

Platelets modulate clotting behavior by 'feeling' their surroundings

Researchers devised a way to separate the physical stiffness of the material where platelets spread out from its biochemical properties. Credit: Wilbur Lam

Platelets, the tiny cell fragments whose job it is to stop bleeding, are very simple. They don't have a cell nucleus. But they can "feel" the physical environment around them, researchers at Emory and Georgia Tech have discovered.

Platelets respond to surfaces with greater stiffness by increasing their stickiness, the degree to which they "turn on" other platelets and other components of the clotting system, the researchers found.

"Platelets are smarter than we give them credit for, in that they are able to sense the physical characteristics of their environment and respond in a graduated way," says Wilbur Lam, MD, PhD, assistant professor in the Department of Pediatrics at Emory University School of Medicine and in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.

The results are published in Proceedings of the National Academy of Sciences. The first author of the paper is research associate Yongzhi Qiu. Lam is also a physician in the Aflac 

Cancer and Blood Disorders Center, Children's Healthcare of Atlanta.

The researchers' findings could influence the design of medical devices, because when platelets grab onto the surfaces of catheters and medical implants, they tend to form clots, a major problem for patient care.

Modifying the stiffness of materials used in these devices could reduce clot formation, the authors suggest. The results could also guide the refinement of blood thinning drugs, which are prescribed to millions to reduce the risk of heart attack or stroke.

The team was able to separate physical and biochemical effects on platelet behavior by forming polymer gels with different degrees of stiffness, and then overlaying them each with the same coating of fibrinogen, a sticky protein critical for blood clotting. Fibrinogen is the precursor for fibrin, which forms a mesh of insoluble strands in a blood clot.

With stiffer gels, platelets spread out more and become more activated. This behavior is most pronounced when the concentration of fibrinogen is relatively low, the researchers found.

"This variability helps to explain platelet behavior in the 3D context of a clot in the body, which can be quite heterogenous in makeup," Lam says.

Qiu and colleagues were also able to dissect platelet biochemistry by allowing the platelets to adhere and then spread on the various gels under the influence of drugs that interfere with different biochemical steps.

Proteins called integrins, which engage the fibrinogen, and the protein Rac1 are involved in the initial mechanical sensing during adhesion, while myosin and actin, components of the cytoskeleton, are responsible for platelet spreading.

"We found that the initial adhesion and later spreading are separable, because different biochemical pathways are involved in each step," Lam says. "Our data show that mechanosensing can occur and plays important roles even when the cellular structural building blocks are fairly basic, even when the nucleus is absent."

Source: Emory Health Sciences

Patient's question triggers important study about blood thinners

Physicians around the world now have guidance that can help them determine the best oral blood thinners to use for their patients suffering from blood clots in their veins, thanks to a patient of The Ottawa Hospital who asked his physician a question he couldn't answer. This new guidance is found in a study published today by JAMA, the Journal of the American Medical Association.

"Right there in the clinic, he identified an important knowledge gap for clinicians. We decided to act on it and find the answer," says hematologist Dr. Marc Carrier, who also a scientist at The Ottawa Hospital and associate professor at the University of Ottawa.

Dr. Carrier was treating Jamie Dossett-Mercer for major blood clotting in his leg veins, called deep vein thrombosis, that reached from his ankle to his groin. If one of these clots were to break off, it could travel to the lung and cause a pulmonary embolism, which is often fatal. These two common medical conditions are known together as venous thromboembolism and form the third leading cause of cardiovascular death.

In recent years, a number of new oral anticoagulants have been approved for use. Faced with eight possible therapies, Dossett-Mercer asked, "How do all these different blood thinners compare head to head?"

Dr. Carrier went looking for the answer. Although he found dozens of trials that studied the effect of different agents separately, none had analyzed all the results together.

His team reviewed 45 randomized trials (involving nearly 45,000 patients) using a process called network meta-analysis, which allows them to set a baseline treatment and compare all the other treatments to that. All the clinical trials they found compared the newer treatments to the standard of care, which is low-molecular-weight heparin (LMWH) with vitamin K antagonists.

Using the LMWH-vitamin K antagonist combination as the central node of the network, they compared safety and effectiveness with seven other anticoagulant therapies for venous thromboembolism: unfractionated heparin (UFH) with vitamin K antagonists; fondaparinux with vitamin K antagonists; LMWH with dabigatran; LMWH with edoxaban; rivaroxaban; apixaban; and LMWH alone.

While they found no major differences in effectiveness and safety, there were some notable variations.

• Patients taking the UFH-vitamin K antagonist combination had a higher percentage who experienced a recurrent blood clot within three months.
• Patients taking rivaroxaban and apixaban had a lower percentage who experienced a major bleeding event within three month.

"This will help physicians tailor their care according to patient characteristics," says Dr. Carrier. "For example, if I am worried about recurrent clotting, but I'm not too worried about the risk of bleeding, then I can select the drug with the best safety profile."

"I was already impressed with Dr. Carrier's exceptional care," says Dossett-Mercer. "But that he would do this research based on a patient question is just astounding."

Source: Ottawa Hospital Research Institute

Platelet-like particles augment natural blood clotting for treating trauma

Associate Professor Tom Barker and Research Scientist Ashley Brown examine bacteria growing on a plate, part of a technique for evolving antibodies in their work on platelet-like particles.
Credit: Georgia Tech Photo

A new class of synthetic platelet-like particles could augment natural blood clotting for the emergency treatment of traumatic injuries -- and potentially offer doctors a new option for curbing surgical bleeding and addressing certain blood clotting disorders without the need for transfusions of natural platelets.

The clotting particles, which are based on soft and deformable hydrogel materials, are triggered by the same factor that initiates the body's own clotting processes. Testing done in animal models and in a simulated circulatory system suggest that the particles are effective at slowing bleeding and can safely circulate in the bloodstream. The particles have been tested with human blood, but have not undergone clinical trials in humans.

Supported by the National Institutes of Health, the U.S. Department of Defense, and the American Heart Association, the research will be reported September 7, 2014, in the journal Nature Materials. Researchers from the Georgia Institute of Technology, Emory University, Children's Healthcare of Atlanta and Arizona State University collaborated on the research.

"When used by emergency medical technicians in the civilian world or by medics in the military, we expect this technology could reduce the number of deaths from excessive bleeding," said Ashley Brown, a research scientist in the Georgia Tech School of Chemistry and Biochemistry and first author of the paper. "If EMTs and medics had particles like these that could be injected and then go specifically to the site of a serious injury, they could help decrease the number of deaths associated with serious injuries."

The bloodstream contains proteins known as fibrinogen that are the precursors for fibrin, the polymer that provides the basic structure for natural blood clots. When they receive the right signals from a protein known as thrombin, these precursors polymerize at the site of the bleeding. The synthetic platelet-like particles use the same trigger, and so are activated only when the body's natural clotting process is initiated.

To create that trigger, the researchers followed a process known as molecular evolution to develop an antibody that could be attached to the hydrogel particles to change their form when they encounter thrombin-activated fibrin. The resulting antibody has a high affinity for the polymerized form of fibrin and a low affinity for the precursor material.

"Fibrin production is on the back end of the clotting process, so we feel that it is a safer place to try to interact with it," said Tom Barker, an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, and one of the paper's co-corresponding authors. "The specificity of this material provides a very important advantage in triggering clotting at just the right time."

The effectiveness of the platelet-like particles has been tested in an animal model and in a microfluidic chamber designed to simulate conditions within the body's circulatory system. In the chamber, tubes about the thickness of a human hair were lined with endothelial cells as in natural blood vessels.

The chamber was used to study normal human blood, as well as human blood that had been depleted of its natural platelets. In platelet-rich blood, clots formed as expected, and blood without platelets did not form clots. When the platelet-like particles were added to the platelet-depleted blood, it was able to clot.

The researchers also tested blood from infants that had undergone open heart surgery, which requires that their blood be diluted, reducing its clotting ability. When platelet-like particles were added to the dilute neonate blood, it was able to form clots.

Finally, safety testing was done on blood from hemophiliac patients. Because that blood lacks the triggers needed to cause fibrin formation, the particles had no effect. Before they can be used in humans, the particles will have to undergo human trials and receive clearance from the U.S. Food & Drug Administration (FDA).

About one micron in diameter, the particles were originally developed to be used on the battlefield by wounded soldiers, who might self-administer them using a device about the size of a smartphone. But the researchers believe the particles could also reduce the need for platelet transfusions in patients undergoing chemotherapy or bypass surgery, and in those with certain blood disorders.

"For a patient with insufficient platelets due to bleeding or an inherited disorder, physicians often have to resort to platelet transfusions, which can be difficult to obtain," said Dr. Wilbur Lam, another of the paper's co-authors and a physician in the Aflac Cancer and 
Blood Disorders Center at Children's Healthcare of Atlanta and the Department of Pediatrics at the Emory University School of Medicine. "These particles could potentially be a way to obviate the need for a transfusion. Though they don't have all the assets of natural platelets, a number of intriguing experiments have shown that the particles help augment the clotting process."

In addition to providing new treatment options, the particles could also cut costs by reducing costly natural transfusions, said Lam, who is also an assistant professor in the Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.

What ultimately happens to the hydrogel particles circulating in the bloodstream will be the topic of future research, noted Brown. Particles of similar size and composition are normally eliminated from the body.

While the platelet-like particles lack many features of natural platelets, the researchers were surprised to find one property in common. Clots formed by natural platelets begin to contract over a period of hours, beginning the body's repair process. Clots formed from the synthetic particles also contract, but over a longer period of time, Brown noted.

Source: Georgia Institute of Technology

Computer model predicts red blood cell flow

Rendering of stream of blood cells. Credit: © Witold Krasowski / Fotolia

Adjacent to the walls of our arterioles, capillaries, and venules -- the blood vessels that make up our microcirculation -- there exists a peculiar thin layer of clear plasma, devoid of red blood cells. Although it is just a few millionths of a meter thick, that layer is vital. It controls, for example, the speed with which platelets can reach the site of a cut and start the clotting process.

"If you destroy this layer, your bleeding time can go way up, by 60 percent or more, which is a real issue in trauma," said Eric Shaqfeh, the Lester Levi Carter Professor and a professor of chemical engineering and mechanical engineering at Stanford University. Along with his colleagues, Shaqfeh has now created the first simplified computer model of the process that forms that layer -- a model that could help to improve the design of artificial platelets and medical treatments for trauma injuries and for blood disorders such as sickle cell anemia and malaria.

The model is described in a paper appearing in the journal Physics of Fluids.

The thin plasma layer, known as the Fåhræus-Lindqvist layer, is created naturally when blood flows through small vessels. In the microcirculation, the layer forms because red blood cells tend to naturally deform and lift away from the vessel walls. "The reason they don't just continually move away from the wall and go far away is because, as they move away, then also collide with other red blood cells, which force them back," Shaqfeh explained. "So the Fåhræus-Lindqvist layer represents a balance between this lift force and collisional forces that exist in the blood."

Because the deformation of red blood cells is a key factor in the Fåhræus-Lindqvist layer, its properties are altered in diseases, such as sickle cell anemia, that affect the shape and rigidity of those cells. The new model, which is a scaled-down version of an earlier numerical model by Shaqfeh and colleagues that provided the first large-scale, quantitative explanation of the formation of the layer, can predict how blood cells with varying shapes, sizes, and properties -- including the crescent-shaped cells that are the hallmark of sickle cell anemia -- will influence blood flow.

The model can also help predict the outcome of -- and perfect -- treatments for trauma-related injuries. One common thing to do during treatment for trauma injuries is to inject saline, which among other things reduces the hematocrit, the blood fraction of red blood cells. With our model, Shaqfeh said, "we can predict how thick the Fåhræus-Lindqvist layer will be with a given hematocrit, and therefore how close the platelets will be to the periphery of the blood vessels -- and how quickly clotting will occur.

Source: American Institute of Physics (AIP)

Hormone that controls supply of iron in red blood cell production discovered by researchers

This is a microscopic image of erythroblasts, which are the bone marrow cells that secrete erythroferrone. Credit: Leon Kautz/UCLA

A UCLA research team has discovered a new hormone called erythroferrone, which regulates the iron supply needed for red blood-cell production.

Iron is an essential functional component of hemoglobin, the molecule that transports oxygen throughout the body. Using a mouse model, researchers found that erythroferrone is made by red blood-cell progenitors in the bone marrow in order to match iron supply with the demands of red blood-cell production. Erythroferrone is greatly increased when red blood-cell production is stimulated, such as after bleeding or in response to anemia.

The erythroferrone hormone acts by regulating the main iron hormone, hepcidin, which controls the absorption of iron from food and the distribution of iron in the body. Increased erythroferrone suppresses hepcidin and allows more iron to be made available for red blood-cell production.

"If there is too little iron, it causes anemia. If there is too much iron, the iron overload accumulates in the liver and organs, where it is toxic and causes damage," said senior author Dr. Tomas Ganz, a professor of medicine and pathology at the David Geffen School of Medicine at UCLA. "Modulating the activity of erythroferrone could be a viable strategy for the treatment of iron disorders of both overabundance and scarcity."

The early findings were reported online June 1 in the journal Nature Genetics.

"Our previous work anticipated that a regulator of hepcidin could be secreted by the bone marrow," said the study's first author, Leon Kautz, a postdoctoral fellow at UCLA. "In this research, we searched for new substances that were made in bone marrow that could fill that role."

Researchers first focused on what happens in the bone marrow after hemorrhage. From there, they focused on a specific protein that was secreted into the blood. This protein attracted their attention because it belonged to a family of proteins involved in cell-to-cell communication. Using recombinant DNA technology, they showed that the hormone suppressed the production of hepcidin and demonstrated the effect it had on iron metabolism.

The team foresees that the discovery could help people with a common congenital blood disorder called Cooley's anemia, also known as thalassemia, which causes excessive destruction of red blood cells and of their progenitors in the bone marrow. Many of these patients require regular blood transfusions throughout their lives. Most iron overload is attributed to the iron content of transfused blood. However, even patients who are rarely, or never, transfused can also develop iron overload.

"Overproduction of erythroferrone may be a major cause of iron overload in untransfused patients and may contribute to iron overload in transfused patients," said study author Elizabeta Nemeth, a professor of medicine at the David Geffen School of Medicine at UCLA and co-director of the UCLA Center for Iron Disorders. "The identification of erythroferrone can potentially allow researchers and drug developers to target the hormone for specific treatment to prevent iron overload in Cooley's anemia."

The discovery could also lead to treatments for other common anemia-related conditions associated with chronic kidney disease, rheumatologic disorders and other inflammatory diseases. In these conditions, iron is "locked up" by the effect of the hormone hepcidin, whose levels are increased by inflammation. Erythroferrone, or drugs acting like it, could suppress hepcidin and make more iron available for red blood-cell production.

The next stage of research is to understand the role of the new hormone in various blood diseases and study the molecular mechanisms through which erythroferrone regulates hepcidin.

Additional study authors included Grace Jung and Erika Valore of UCLA and Stefano Rivella of Weill Cornell Medical College in New York.

The study was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Heart, Lung and Blood Institute.

The Board of Regents of the University of California is the owner of patent applications and uses directed at erythroferrone, which are managed by UCLA's Office of Intellectual Property and Industry Sponsored Research. This intellectual property is the subject of license negotiations with a company for which authors Ganz and Nemeth are scientific advisors and equity holders. Other disclosures are available in the manuscript.

Source: University of California, Los Angeles (UCLA), Health Sciences

The bloody truth: How blood donations can save animals' lives

Donated blood can be quickly regenerated by the animal’s organism. Credit: Felizitas Steindl / Vetmeduni Vienna

Blood transfusions are of importance not only in human medicine. Also animals do need blood donations. The University of Veterinary Medicine, Vienna operates a blood bank for dogs for more than a decade. But also cats can donate blood for acute emergencies. Horses need blood donations especially during operations that involve high blood loss. Sheep, goats and other ruminants require transfusions when plagued by serious infestations of parasites. Three vets from different areas of expertise explain how blood transfusions work with different animal species and how they can save lives.

Blood can hardly be created through artificial means, but it can be transferred within a species. Reasons for a blood transfusion among dogs and cats are usually serious accidents, large operations, certain types of cancer, cases of intoxication with rat poison, serious infectious diseases such as the tick-borne babesiosis, and blood illnesses including haemolytic or inherited bleeding disorders such as haemophilia.

At the University of Veterinary Medicine, Vienna dog owners can bring their animals to donate blood regularly or as needed. Blood donations two to four times a year per dog is the maximum. About 15 minutes are required for a donation. Dogs must have a minimum weight of 25 kilograms and usually donate about 450 millilitres of blood. For cats, depending on their size, the amount taken is about 50 millilitres. Cats are typically sedated for the procedure. For most dogs, on the other hand, donating blood does not involve any serious stress. Should a donation cause too much anxiety or stress, the animal will be excluded as a donor.

Not all blood is alike

As with people, animals also have different blood types. Animal blood, as well as human blood, is divided into various groups based on different surface proteins found on the red blood cells. More than twelve different blood type systems have been described for dogs, although in practice dogs are only tested for DEA 1.1 positive or DEA 1.1 negative. Cats exhibit three different types of blood, horses eight and bovines eleven. The transfusion of an unsuitable blood type can have fatal consequences for animals, especially when a cat with blood type B receives type A blood. For horses and ruminants, the first time transfusion of 'wrong' donor blood is generally safe. With each additional transfusion, however, blood types become crucial, as the animals have produced antibodies against the foreign blood that can cause serious immune reactions.

Blood donations come with a health check

Dogs and cats can be registered as blood donors at the Clinical Unit of Internal Medicine Small Animals of the Vetmeduni Vienna. The animals receive a donor card and undergo a thorough examination before each donation. This mandatory health check includes a complete blood count, a test for blood parasites, and a check-up for viral infections.

"Donating blood does not harm the animals. The donated amount can be quickly regenerated by the animal's organism," says specialist for small animal internal medicine and blood bank coordinator Nicole Luckschander-Zeller. "We pay special attention to making sure that donor animals feel good during donation. That's why, after every donation, we give the animals a little snack."

Dog and cat blood is not only used as a whole. Individual blood components, such as plasma or erythrocyte concentrates, are stored and used when needed.

Horses as blood donors and recipients

There are various reasons for blood donations in equine medicine. These include clotting disorders of the blood, anaemia, poisonings or serious infectious diseases as well as perioperative blood loss. For the latter, blood is stored and kept ready for use during surgery in areas with strong blood supply, such as the nose and jaw. A blood transfusion helps to sustain adequate circulation of the animal during the operation and speeds recovery.

"The owners of diseased horses occasionally bring the suitable donor animal with them," says René van den Hoven, director of the Clinical Unit for Equine Internal Medicine at the Vetmeduni Vienna. The hospital also maintains a number of its own donor horses. The number of donations and the volume of the blood collected are registered in the horse's file, making it possible to plan future dates for donations without compromising the animal's health.

A maximum of five to seven litres of blood can be collected from a horse per donation. The blood must then be transfused into a patient within just a few hours. Storing whole equine blood is not a suitable option. As only plasma is desired for some treatments, the plasma is separated from the whole blood. Plasma is used for specific applications, for example to improve the healing of complicated wounds or during eye operations. Patients with massive protein loss can also be successfully treated with plasma. Protein loss may occur as a consequence of serious burn trauma, severe diarrhoea, tumours or chronic inflammatory intestinal disease, pleurisy or peritonitis.

Ruminants with anaemia need donated blood

Sheep, goats, lamas and alpacas are especially at risk of being infested by blood-sucking parasites out on the pasture. Ingested through the mouth, the worms come to inhabit the intestinal tract. A high level of parasitic infestation leads to serious cases of anaemia that may be fatal for the animals. "These acute patients require a rapid blood transfusion. Ruminants also receive blood for wounds with heavy blood loss, though this luckily is not often the case," explains the specialist for ruminant medicine, Lorenz Khol

Source:University of Veterinary Medicine -- Vienna

Odor that smells like blood: Single component powerful trigger for large carnivores

African wild dogs compete for a log impregnated with blood or a single component. Both were equally attractive. Credit: Linköping University

People find the smell of blood unpleasant, but for predatory animals it means food. When behavioural researchers at Linköping University in Sweden wanted to find out which substances of blood trigger behavioural reactions, they got some unexpected results.

Matthias Laska is professor of zoology, specialising in the sense of smell. For some time his focus has been on scents that directly affect the behaviour of animals.

"For predators, food scents are particularly attractive, and much of this has to do with blood. We wanted to find out which chemical components create the scent of blood," he says.

The study, conducted at Kolmården Wildlife Park, found that for the animals, one particular component of blood odour was just as engaging as the blood odour itself.

"It's a completely new discovery that raises interesting questions on evolution," says Prof Laska.

The study has been published in the scientific journal PLOS ONE.

When Prof Laska did a search for the contents of volatile substances in mammalian blood, he found nothing. Human blood has been analysed for disease markers, but we have very little information on the substances that give blood its characteristic scent.

A master's student was sent to Friedrich-Alexander-Universität in Erlangen Germany, to analyse mammalian blood with the help of gas chromatography and mass spectrometry, methods used for separating and identifying chemical compounds in a sample. The machine detected some 30 substances, of which some are decomposition products from fats. But the machine lost the job to the human scent experts who had also been engaged. They identified scents that the gas chromatograph missed completely.

One substance stood out: an aldehyde called trans-4,5-epoxy-(E)-2-decenal, which emits the typical metallic scent that humans associate with blood.

Once the researchers had identified a scent candidate that the predators should be attracted to, they wanted to test whether the predators were actually attracted to it in reality. So they designed a study to be conducted at Kolmården Wildlife Park, involving four predator species. How would the four predators -- Asian wild dogs, African wild dogs, South American bush dogs and Siberian tigers -- react when they caught a whiff of the scent?

Half-metre long wooden logs were impregnated with four different liquids: lab-produced aldehyde, horse blood, fruit essence, and a near-odourless solvent. The animals were exposed to one scent per day in their regular enclosure, while a group of students carefully observed their behaviour.

The results were unequivocal. The logs containing aldehyde were just as attractive stimuli as those containing blood, while the two other logs aroused little interest. The commonest behaviours were sniffing, licking, biting, pawing and toying. The tiger was the most persistent, while the South American bush dogs lost interest more quickly than the other species.

The study is the first to show that a single component can be just as attractive as the complex odour.

"How this has developed through evolution is an interesting question. Perhaps there is a common denominator for all mammalian blood," says Prof Laska.

He has plans for several follow-ups of the study, including how prey animals such as mice react to blood odour.

For the wildlife park, the study provided results that can be used in its daily operations. Animals in captivity require stimulation, so as not to deteriorate or become fat. The odourised logs can be a popular addition to the animal's environment.

Source: Linköping University

Nanotechnology against malaria parasites

After maturation, malaria parasites (yellow) are leaving an infected red blood cell and are efficiently blocked by nanomimics (blue). Credit: Fig: modified by University of Basel with permission from ACS

Malaria parasites invade human red blood cells, they then disrupt them and infect others. Researchers at the University of Basel and the Swiss Tropical and Public Health Institute have now developed so-called nanomimics of host cell membranes that trick the parasites. This could lead to novel treatment and vaccination strategies in the fight against malaria and other infectious diseases. Their research results have been published in the scientific journal ACS Nano.

For many infectious diseases no vaccine currently exists. In addition, resistance against currently used drugs is spreading rapidly. To fight these diseases, innovative strategies using new mechanisms of action are needed. The malaria parasite Plasmodium falciparum that is transmitted by the Anopheles mosquito is such an example. Malaria is still responsible for more than 600,000 deaths annually, especially affecting children in Africa (WHO, 2012).
Artificial bubbles with receptors

Malaria parasites normally invade human red blood cells in which they hide and reproduce. They then make the host cell burst and infect new cells. Using nanomimics, this cycle can now be effectively disrupted: The egressing parasites now bind to the nanomimics instead of the red blood cells.

Researchers of groups led by Prof. Wolfgang Meier, Prof. Cornelia Palivan (both at the University of Basel) and Prof. Hans-Peter Beck (Swiss TPH) have successfully designed and tested host cell nanomimics. For this, they developed a simple procedure to produce polymer vesicles -- small artificial bubbles -- with host cell receptors on the surface. The preparation of such polymer vesicles with water-soluble host receptors was done by using a mixture of two different block copolymers. In aqueous solution, the nanomimics spontaneously form by self-assembly.

Blocking parasites efficiently

Usually, the malaria parasites destroy their host cells after 48 hours and then infect new red blood cells. At this stage, they have to bind specific host cell receptors. Nanomimics are now able to bind the egressing parasites, thus blocking the invasion of new cells. The parasites are no longer able to invade host cells, however, they are fully accessible to the immune system.

The researchers examined the interaction of nanomimics with malaria parasites in detail by using fluorescence and electron microscopy. A large number of nanomimics were able to bind to the parasites and the reduction of infection through the nanomimics was 100-fold higher when compared to a soluble form of the host cell receptors. In other words: In order to block all parasites, a 100 times higher concentration of soluble host cell receptors is needed, than when the receptors are presented on the surface of nanomimics.

"Our results could lead to new alternative treatment and vaccines strategies in the future," says Adrian Najer first-author of the study. Since many other pathogens use the same host cell receptor for invasion, the nanomimics might also be used against other infectious diseases. The research project was funded by the Swiss National Science Foundation and the NCCR "Molecular Systems Engineering."

Source: University of Basel

Promising compound rapidly eliminates malaria parasite

A new report says that the rapid action of (+)-SJ733 will likely slow malaria drug resistance. Credit: Peter Barta, St. Jude Children's Research Hospital

An international research collaborative has determined that a promising anti-malarial compound tricks the immune system to rapidly destroy red blood cells infected with the malaria parasite but leave healthy cells unharmed. St. Jude Children's Research Hospital scientists led the study, which appears in the current online early edition of the Proceedings of the National Academy of Sciences (PNAS).

The compound, (+)-SJ733, was developed from a molecule identified in a previous St. Jude-led study that helped to jumpstart worldwide anti-malarial drug development efforts. Malaria is caused by a parasite spread through the bite of an infected mosquito. The disease remains a major health threat to more than half the world's population, particularly children. The World Health Organization estimates that in Africa a child dies of malaria every minute.

In this study, researchers determined that (+)-SJ733 uses a novel mechanism to kill the parasite by recruiting the immune system to eliminate malaria-infected red blood cells. In a mouse model of malaria, a single dose of (+)-SJ733 killed 80 percent of malaria parasites within 24 hours. After 48 hours the parasite was undetectable.

Planning has begun for safety trials of the compound in healthy adults.

Laboratory evidence suggests that the compound's speed and mode of action work together to slow and suppress development of drug-resistant parasites. Drug resistance has long undermined efforts to treat and block malaria transmission.

"Our goal is to develop an affordable, fast-acting combination therapy that cures malaria with a single dose," said corresponding author R. Kiplin Guy, Ph.D., chair of the St. Jude Department of Chemical Biology and Therapeutics. "These results indicate that SJ733 and other compounds that act in a similar fashion are highly attractive additions to the global malaria eradication campaign, which would mean so much for the world's children, who are central to the mission of St. Jude."

Whole genome sequencing of the Plasmodium falciparum, the deadliest of the malaria parasites, revealed that (+)-SJ733 disrupted activity of the ATP4 protein in the parasites. The protein functions as a pump that the parasites depend on to maintain the proper sodium balance by removing excess sodium.

The sequencing effort was led by co-author Joseph DeRisi, Ph.D., a Howard Hughes Medical Institute investigator and chair of the University of California, San Francisco Department of Biochemistry and Biophysics. Investigators used the laboratory technique to determine the makeup of the DNA molecule in different strains of the malaria parasite.

Researchers showed that inhibiting ATP4 triggered a series of changes in malaria-infected red blood cells that marked them for destruction by the immune system. The infected cells changed shape and shrank in size. They also became more rigid and exhibited other alterations typical of aging red blood cells. The immune system responded using the same mechanism the body relies on to rid itself of aging red blood cells.

Another promising class of antimalarial compounds triggered the same changes in red blood cells infected with the malaria parasite, researchers reported. The drugs, called spiroindolones, also target the ATP4 protein. The drugs include NITD246, which is already in clinical trials for treatment of malaria. Those trials involve investigators at other institutions.

"The data suggest that compounds targeting ATP4 induce physical changes in the infected red blood cells that allow the immune system or erythrocyte quality control mechanisms to recognize and rapidly eliminate infected cells," DeRisi said. "This rapid clearance response depends on the presence of both the parasite and the investigational drug. That is important because it leaves uninfected red blood cells, also known as erythrocytes, unharmed."

Laboratory evidence also suggests that the mechanism will slow and suppress development of drug-resistant strains of the parasite, researchers said.

Planning has begun to move (+)-SJ733 from the laboratory into the clinic beginning with a safety study of the drug in healthy adults. The drug development effort is being led by a consortium that includes scientists at St. Jude, the Swiss-based non-profit Medicines for Malaria Venture and Eisai Co., a Japanese pharmaceutical company.

Source: St. Jude Children's Research Hospital