Unfortunately, less than 5 percent of healthy Britons donate blood making its availability scarce. The average donation comes from educated, white males aged 25-50. This adds further complication for black people who require a transfusion. In blood transfusions on cases of severe wounds, pints and pints of blood can be wasted because as soon as it is pumped in it is pumped out of the wound by the heart. These factors have added to a race to create an ‘artificial blood,’ that can be used in surgery to prevent wasting donated blood.
Of course, the artificial blood in contemplation at the moment is nowhere near the sophistication and complexity of human blood. The use of the word ‘artificial blood,’ is maybe too ambitious a label for these solutions, because none can replace the clotting and infection-fighting abilities of whole blood that white blood cells and platelets provide. But these liquids, like red blood cells, carry oxygen from the lungs to the rest of the respiring cells and carry carbon dioxide back.
Steven A. Gould explains the main use of ‘artificial blood.’
"The main benefit of these products will be to reduce the amount of donated blood a patient receives. That can minimise the risk of infection [because the chemicals can be sterilised more rigorously than blood] and will preserve blood for cases where it is really needed."
Blood substitutes can stay fresh for six months or more; red blood cells go bad within six weeks. The artificial compounds bear none of the proteins and sugars (commonly called antigens) that coat blood cells and separate them into eight distinct types. Theoretically, the synthetic blood could be pumped into anyone, without fear of provoking a serious allergic reaction. Donated blood cannot be transfused into anyone because of its blood group.
Blood Group UK Population
O Rh-positive 38 percent
O Rh-negative 7 percent
A Rh-positive 34 percent
A Rh-negative 6 percent
B Rh-positive 9 percent
B Rh-negative 2 percent
AB Rh-positive 3 percent
AB Rh-negative 1 percent
In an emergency, anyone can receive type O Red Blood Cells, and type AB individuals can receive Red Blood Cells of any ABO type. Therefore, people with type O blood are known as “universal donors” and those with type AB blood are known as “universal recipients.” In addition, AB Plasma donors can give to all blood types. The use of ‘artificial blood’ could eliminate these problems.
The use of a substitute for blood has been going on for hundreds of years. In 1868 when they first extracted haemoglobin, the oxygen-bearing protein in red blood cells. Haemoglobin failed as a blood replacement because it works only when intact and when assisted by a cofactor found in red blood cells. Stripped from its protective cell and its molecular team-mate, haemoglobin is quickly snipped in two by enzymes, and the fragments, which act as toxins, can poison the kidneys. This gave rise to one type of artificial blood whose haemoglobin could act without its cofactor. This involves modifying haemoglobin so that it works without its cofactor and resists the body's attempt to split it into toxic halves. One such example is PolyHeme; a solution of chemically modified haemoglobin derived from human blood. The process of separation, filtration and chemical modification produces PolyHeme. Haemoglobin is first extracted from red blood cells and filtered to remove impurities. The purified haemoglobin is next chemically modified using a multi-step process to create a polymerised form of haemoglobin designed to avoid the undesirable effects that can occur in the kidneys as explained before. The modified haemoglobin is then incorporated into a solution, which can be administered as an alternative to transfused blood.
The other main source of artificial blood is perfluorochemicals. This is the synthetic organic material, composed of silicone and fluorocarbon and is known for its ability to carry oxygen. In the 1960's Clark and Gollan demonstrated that mice immersed in oxygenated silicone oil or liquid fluorocarbon could breathe in the liquid. In the same year Chang demonstrated that artificial cells formed from a hybrid of silicone rubber and haemolysate were very efficient in carrying and releasing oxygen. However, these solid elastic silicone rubber artificial cells did not survive sufficiently in the circulation. Extensive development was carried out in Japan by Naito, Yokoyama resulting in the development in 1976 of fluosol-DA 20 suitable for clinical testing. The biggest advantage of perfluorochemicals is that they are synthetic and can be chemically produced in large amounts without having to depend on donor blood or other biological sources.
The future of artificial blood is definitely optimistic. Its advantages absolutely outweigh its disadvantages. As technology advances, the blood substitute’s complexity may evolve to be as sophisticated as real human blood – acting not only as a carrier of substances, but also a defence system against disease and trauma. The artificial blood in the pipeline at the moment is no where as near as sophisticated as this, but will certainly save many lives if it comes on the market. It will stop blood wastage in operating theatres ensuring that there are ample supplies of natural blood available.
