Blood, blood everywhere — but not a drop when you need it. In the U.S. alone, there are around 17,000 preventable trauma deaths each year due to untreated hemorrhagic shock. Basically, that means someone loses a fatal amount of blood before they can reach the hospital more than 46 times per day.
That’s why scientists have been working for many decades to come up with a substitute for two pressing problems. Paramedics in battlefields and other challenging places need blood for emergency situations, and doctors need a plentiful supply of blood to transfuse into patients with sickle cell disease, many of whom have trouble finding blood donors.
To remedy the transfusion issue, researchers at the U.K.’s National Health Service are launching an ambitious trial this year to test whether blood made from stem cells will act the same way in the body as regular donated blood.
The NHS researchers were quick to point out that while blood substitutes can be a vital bridge to helping people in acute situations, blood donations will still be necessary in the future.
“It would be unfeasible to make blood in the lab for everyone,” says Ash Toye, a biochemist at the University of Bristol who is working on the NHS study. “But we could make blood for people with very rare blood types or who have reacted to donated blood and so are difficult to match.”
The other challenge — getting blood where it needs be — is also getting a boost this year. Allan Doctor, a researcher at Washington University in St. Louis, has created an artificial red blood cell that picks up oxygen in the lungs and transports it throughout the body. The cells are made from purified human hemoglobin — the oxygen-carrying component inside blood cells. Those cells are then coated with a special synthetic polymer.
The step of adding the synthetic polymer is important, Doctor notes. There have been a bunch of efforts in the past to create artificial substances that could carry oxygen from the lungs to the rest of the body. But some of the blood faltered because it would fail to release the oxygen. Or the uncoated hemoglobin caused adverse effects like heart attacks.
The synthetic polymer coating appears to solve these issues, according to Doctor. The coating is designed to respond to changes in blood pH, so the cells are programmed to pick up oxygen in the lungs — where pH is high — and let it go where in places with low oxygen — where pH is low.
The result is a product that can be freeze-dried as a powder and could be used on ships, battlefields, or even in space. The synthetic cells are immune silent, meaning they can be used with any blood type, and can be stored at room temperature and mixed with water, ready for immediate use anywhere.
Doctor says the blood powder — ErythroMer — extends transfusion therapy to many challenging locations, including warzones. For U.S. military personnel, a quarter of in-field deaths are preventable, and of these death, 90 percent are due to hemorrhagic shock, when they die not from damage to major organs but because they effectively bleed to death before hospital care is available.
Powdered blood could be carried on helicopters or ambulances and used to buy necessary time to get a wounded soldier to a medical center, where he or she could receive transfusions. Patients would still need other blood: typical blood cells circulate in the body for about four months, and the artificial blood cells only last a few days.
Doctor says he has not yet designed the packaging, but he envisions a partitioned bag (with dry Erythromer and sterile water) that can be popped open easily by hand and then mixed.
“The delivery system will be simple, light, portable,” he says. “We also anticipate use in emergency rooms to stabilize decompensating patients on arrival,” which would eliminate the need to use emergency donor blood that can cause adverse reactions.
The powder, which looks like paprika, may also be useful in resource-limited countries where it is difficult to provide adequate blood banking or develop a stable donor pool, Doctor says.
The result is a product that can be freeze-dried as a powder and could be used on ships, battlefields, or even in space.
“Since ErythroMer can be freeze-dried and stored for prolonged periods at ambient temperature, it may also be stockpiled in ‘medical disaster depots’ in anticipation of mass casualty incidents like the Boston Marathon bombing,” he says.
It sounds fantastic, but the revolution in blood may take some time. ErythroMer has been tested in mice, and is now in testing in larger animals. Doctor says he hopes the product will enter human trials within a decade.
Right now, there are no accepted oxygen-carrying blood substitutes available for use in the U.S., although there are some substances that can expand the volume of blood and can be used by people who refuse blood transfusions for religious reasons.
The hurdles are high. For decades, scientists have searched for different ways to create oxygen-carrying blood substitutes. One early success used perfluorocarbons instead of hemoglobin. Perfluorocarbons are tiny molecules that contain fluorine and carbon atoms. They are capable of dissolving large amounts of many gases, including oxygen — which makes them a target for researchers hoping to develop substances that can carry oxygen.
Approved by the FDA in 1989, the product was made by the Japanese and was called Fluosol-DA-20. But due to the substance’s side effects, complexity of use, and limited success, it was withdrawn in 1994. It remains the only oxygen-carrying therapeutic ever fully approved by the FDA.
Another recent effort, Oxycyte, was also based on perfluorocarbons. The company that made Oxycyte halted trials in 2014, citing difficulties in enrolling patients.
Human trials of another cow-hemoglobin-based substance, Hemopure, raised so many safety concerns that the FDA banned further clinical testing of the product on human test subjects in the United States.
It remains to be seen if ErythroMer will prove successful, or if the NHS trial of stem cells will create plentiful, inexpensive blood for transfusions. But it’s possible that soon, blood could be everywhere it’s needed — from undersea stations to deep space.