When William Harvey first described the circulation of blood in 1616, scientists starting thinking about whether blood could be removed and replaced by other liquids, such as wine and milk, for example. They thought that by doing so, diseases could be cured and even that personalities could be changed. I and II and, more recently, by the discovery in the early 1980s that HIV could be transmitted by blood transfusion.
Blood is now safe, thanks to improved collection and screening by blood banks.
But it still has to be cross-matched and can be stored for only a few weeks before it has to be discarded. Therefore, the replacement solutions being developed today are more accurately described as oxygen carriers. There are basically two types of oxygen carriers, which differ in the way they transport oxygen. One is based on perfluorochemicals, the other on hemoglobin. Perfluorochemicals are inert materials that can dissolve approximately 50 times more oxygen than blood plasma, the liquid that surrounds the red cells.