Tens of thousands of people die from hemorrhage every year in the United States before reaching a hospital. This happens because ambulances, medical helicopters, and military doctors cannot routinely transport blood, which would deteriorate very quickly without proper refrigeration.
That’s why scientists are seeking to develop artificial blood that can be stored as a powder and reconstituted by doctors on-site to save lives.
At the University of Maryland School of Medicine in Baltimore, where part of this research is being conducted, a white rabbit lies on the floor of a cage. It is in a “special intensive care unit that we created for our rabbit resuscitation,” says Dr. Allan Doctor, a scientist at the school.
The doctor’s team has just drained blood from the animal to simulate what happens to a person suffering from hemorrhage due to an injury, such as a car accident or a battlefield wound.
“This rabbit is still in shock. You can see it’s lying there, motionless. It’s like it’s at the scene of an accident,” says Doctor. “If we did nothing, it would die.”
But Doctor and his team will save this rabbit today. They will fill its veins with something they hope will finally allow them to achieve a goal that has frustrated researchers for decades: developing safe and effective artificial blood.
“Such a good little bunny,” says Danielle Waters, a technician on Doctor’s team, as she gently lifts the rabbit and begins infusing it with three large syringes of artificial blood.
Doctor’s team produces synthetic blood from hemoglobin, the protein that oxygenates the body. The researchers extract hemoglobin from expired blood and encase the protein in a fat bubble, essentially creating artificial red blood cells.
The protective bubble is the innovation that Doctor believes will solve the safety problems caused by other attempts to produce synthetic blood. Those other attempts also used hemoglobin, but exposed hemoglobin can be toxic to organs, he says.
“We have to hide the hemoglobin inside a cell. It’s an artificial cell that makes it safe and effective,” says Doctor.
The scientists then lyophilize the artificial red blood cells into a powder that can remain viable until an emergency.
“It’s designed so that, when needed, a doctor can mix it with water and, in one minute, you’ll have blood,” says Doctor.
“It can sit on shelves for years and be easily transported. And so the point is that you can administer a transfusion at the scene of an accident,” says Doctor.
In addition to use in emergency medicine, military doctors could also use artificial blood to save wounded soldiers. The Department of Defense is investing more than $58 million to help fund a consortium developing the doctor’s synthetic blood, along with other components that enable clotting and maintain blood pressure.
“The leading preventable cause of death on the battlefield is still hemorrhage these days,” says Colonel Jeremy Pamplin, project manager at the Defense Advanced Research Projects Agency. “That’s a real problem for the military and the civilian world.”
The doctor is optimistic that his team may be on the verge of solving that problem with their artificial red blood cells, called ErythroMer. Doctor was a cofounder of KaloCyte to develop the blood and serves on the board and as the company’s chief scientific officer.
“We’ve successfully recapitulated all the functions of blood that are important for resuscitation in a system that can be stored for years at room temperature and used at the scene of an accident,” he says.
Promising Results in Animal Tests
Back in the lab, Waters finishes infusing the three vials of synthetic blood into the rabbit after about 10 minutes.
“My God, bunny, you made it,” she says as she places it back in the cage. “There you go.”
Almost immediately, a monitor tracking the rabbit’s vital signs shows that its heart rate, blood pressure, and other key metrics have recovered from near death to nearly normal. It is starting to resume normal behavior, like moving on its own and drinking water.
“The really positive sign is that it’s nice and pink,” says Doctor. “Its eyes are pink. Its ears are pink. That’s a good sign that it has plenty of oxygen in its blood and that it’s being distributed effectively. It’s breathing comfortably and calmly. It’s incredible how quickly it works.”
Doctor’s team has tested their artificial blood in hundreds of rabbits, and so far, it appears safe and effective.
“This would change the way we can care for people who are bleeding outside of hospitals,” says Doctor. “It would be transformative.”
Like other rabbits used in these experiments, this animal will later be euthanized so researchers can perform a necropsy to ensure the artificial blood caused no damage to tissues or organs.
Human Tests Still to Come
Although the results so far seem reason for optimism, Doctor says he still needs to prove to the Food and Drug Administration (FDA) that his artificial blood would be safe and effective for humans.
But he hopes to start testing it in humans within two years. A Japanese team is already testing a similar synthetic blood in people.
“I’m very hopeful,” says Doctor.
Other experts remain cautious. Many promising attempts to create artificial blood have ultimately proven unsafe.
“I think it’s a reasonable approach,” says Tim Estep, a scientist at Chart Biotech Consulting who advises companies developing artificial blood.
“But since this field has been so challenging, the proof will be in the clinical trials,” he adds. “While I’m optimistic overall, betting on any technology right now is, overall, tough.”
Source: npr.org by Rob Stein