Human blood suitable for transfusion is always in short supply despite over 100 million donations every year. Even if the supply of blood was vastly increased, there would still be many places in the world that lacked the proper facilities to store and manage it all. Scientists have been looking at blood substitutes to solve these issues for years, but a variety of concerns have prevented any of them from reaching patients. The HaemO2 project from the University of Essex in England might be the first real success after designing a safer oxygen carrier molecule that can be stored at room temperature for long periods, while also avoiding the toxic effects seen with other blood substitutes.
Human blood is brimming with immune cells and a plethora of proteins, and the researchers are interested in the red blood cell for transfusion. These donut-shaped, non-nucleated cells are the main solid constituent of blood, giving it that distinctive red color. The red actually comes from the molecule that is at the heart of a red blood cell's ability to carry oxygen -- hemoglobin. This iron-bearing protein latches onto an oxygen atom in the lungs, then releases it elsewhere in the body to keep your cells chugging along. This is what the HaemO2 project has apparently replicated.
The issue that had stymied past attempts to develop artificial blood is that hemoglobin and hemoglobin-like molecules can have toxic side effects when not contained within the walls of a red blood cell. When exposed to the bloodstream, these proteins will decompose into reactive “ferryl” intermediates and free radicals. That's definitely not the kind of thing you want in your blood.
HaemO2 is based on a modified hemoglobin molecule, but it has been specifically designed to be broken down by naturally occurring vitamin C and uric acid in the blood. The team essentially inserts a few additional amino acids (tyrosine) in the hemoglobin molecule that trigger this safer self destruct. The modified hemoglobin protein is created by inserting recombinant genes into E. coli bacteria and growing a culture. The bacteria produce the desired protein as they go about their usual metabolic activity until it's time to harvest the "red" cells. The new recombinant proteins are then purified and concentrated, ready for (hopefully) saving lives.
The advantages of an artificial oxygen carrier in the blood are vast. Emergency responders wouldn't have to worry about blood typing in the midst of a disaster scenario because there would be no blood type markers in artificial blood. HaemO2 can last up to two years at room temperature(Opens in a new window), making it perfect for emergencies and distribution to remote areas. A blood replacement would also be safer for immune-compromised individuals to receive as a transfusion. Even if your immune system works fine, human blood can come with risks (even if it makes you smarter). There's always the possibility that as-yet-undiscovered bloodborne pathogens will pop up in the blood supply, which is what we saw in the early days of the HIV epidemic.
The University of Essex has been granted patents(Opens in a new window) on its custom hemoglobin design in the US and Australia, and approval is pending in the EU. There's still much work to be done before HaemO2 makes its way into anyone's veins, but it might revolutionize transfusions when it finally does.Tagged In
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