Blood is indeed the river of life. It carries oxygen and nutrients to all the cells of the body and removes toxic byproducts to keep everything clean and healthy. The cardiovascular system is a closed system in that it constantly recirculates, and like submarines, leaks from the system can be disastrous, and deadly. Blood is also a living, biological material and this makes it very difficult to handle. It must be taken from a living person, treated to prevent clotting, and stored in a manner that prevents decay. The logistics of this are very difficult, particularly when blood is needed in places such as war zones, very remote areas, and even in space. If someone is severely injured and in danger of exsanguinating – – the $10 word for “bleeding to death” – – then rapidly replacing this loss blood is essential. IV fluids and plasma expanders and other assorted intravenous materials can be given to buy time, to keep the volume in the system to an adequate level, and to keep everything circulating, but these materials have a major drawback – – they don’t carry oxygen. So the only life-saving remedy is to replace the blood.
Over the years there have been many attempts to develop artificial blood, a product that would carry oxygen and be logistically more friendly. Something that did not require anticoagulation, refrigeration, and care in its transport and storage. Something that could be carried and stored like a bottle of water. Many of these endeavors have proven to be unsuccessful.
Blood substitutes have traditionally been based on hemoglobin, the oxygen-carrying molecule within the red blood cells (RBCs). Products such as HemoPure (made from bovine hemoglobin), PolyHeme (made from outdated human blood), and HemAssist (based on cross-linked hemoglobin) all seemed promising but safety issues arose with each and these have not been completely resolved.
Other forms of “artificial blood” have been based on perfluorocarbon emulsions. These too have faced many problems.
Another problem with blood therapy is keeping a steady and safe supply. There are only so many donors and the blood’s shelf-life is not all that long. If blood could be manufactured so that an adequate and steady supply could be maintained, this would be a giant step forward.
Well, now it seems that manufactured truly artificial blood might be on the horizon. A group at the University of Edinburgh is beginning clinical trials on a process for making red blood cells from stem cells. Since these would be “real” RBCs, the technique holds promise.
