By Efrat Ohayon, Staff Writer
Every second matters when someone is losing blood. In fact, there has been a shift in trauma cases from ensuring that the airway is clear to guaranteeing there is proper circulation. The Journal of the American College of Surgeons has reinforced this, changing the protocol to prioritize circulation before securing the airways. This has led to improved outcomes for patients. After stopping the blood flow from a wound, the blood that has been lost must be replaced, and for a successful blood transfusion, the same type of blood must be used, presenting an issue as there is not necessarily the correct blood type present for transfusion at all times. In fact, according to the American Red Cross, every two seconds someone in the United States needs a transfusion. But what if there isn’t the correct blood type present, or not enough of it? Scientists in Japan have developed an alternative to blood transfusions by purifying human hemoglobin and encapsulating it in liposomes.
Normally, after being donated, red blood cells are stored for up to forty-two days in refrigeration before being disposed of. Researchers at Nara Medical University have developed a way in which there can be an alternative to human blood. This lab-produced blood can last for up to two years, stored at room temperature.
The key is that this stored blood is not made up of red blood cells, but rather of hemoglobin vesicles (HbVs). These vesicles are liposome particles that contain concentrated human hemoglobin on the inside. Hemoglobin is the protein that is found in red blood cells that is responsible for binding to and carrying oxygen. By taking the human hemoglobin protein and encapsulating it with a liposome, researchers are able to utilize the oxygen-carrying function of the protein, while protecting the hemoglobin from interacting with the bloodstream in ways that are not desired. Previous versions of hemoglobin-based oxygen carriers contained hemoglobin proteins that were not enclosed, which led to a greater risk of mortality. Researchers in Japan remodeled the HbVs by encapsulating the hemoglobin protein in liposome particles, containing the protein.
So, why is this any different than previous discoveries made in the lab? First of all, this type of blood is independent, meaning no cross-matching needs to occur before being administered. Another benefit is that since it is made from purified hemoglobin, rather than donated, it does not have the risk of transmitting diseases. One of the more significant advantages is that it can be stored for up to two years, which means that this kind of blood could be a significant development for remote areas that don’t have cold storage available.
As of now, it has been determined that while these transfusions are safe in small quantities, there are still challenges with administering a larger amount, which is more realistic to emergency scenarios. Primarily, there have been issues with the tightening of veins, known as vasoconstriction, as well as high blood pressure, known as hypertension. These concerns come from earlier studies done with hemoglobin-based oxygen carriers, in which non-encapsulated hemoglobin would react with nitric oxide, which keeps the blood vessels non-constricted.
Currently, the researchers at Nara Medical University Hospital are testing doses of up to 400 mL to determine what other side effects need to be watched. Researchers are worried about side effects such as cardiac strain, elevated blood lipids, and severe allergic reactions. To combat this, trial participants are given premedications to reduce the likelihood of an immune response to the transfusion.
If these trials succeed, the benefit of this is vast, from being able to store blood ready for transfusions in areas where refrigeration is not available, to having large amounts of blood ready to use in critical situations, ready for administration.
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