Chemical Technology July 2015

In pursuit of the perfect blood

by Gavin Chait

Mad Max is captured and forced into slavery as a ‘blood bag’ in “Fury Road”, the latest episode in the ongoing post- apocalypse saga. He is there to provide an endless source of fresh blood transfusions to ensure the health of the War Boys as they maintain the authority of the villainous Imortan Joe.

B ack in the real world, we go through 85million units of red blood cells for transfusion annually; that’s about 38 million litres of blood. And demand is growing at about 6-8 % a year, while supply is growing at 2-3 %. This is despite vast improvement in therapy around key-hole surgery or coronary bypasses where far less blood is now required. Part of this is that healthcare is now more universally available, and part is that longer lifespans mean that the unhealthy old need more transfusions during cancer treat- ment. Patients undergoing bone-marrow transplants require platelet donations from 120 people and red blood cells from 20 people. Expanders (such as Ringer’s Lactate solution – a solution of various salts isotonic with blood) have helped to reduce the demand for blood. Our bodies carry a lot more red blood cells (erythrocytes) than strictly necessary for our sedentary lifestyles, since you’re prepared – at a moment’s notice – to start sprinting and your body will then need the extra oxygen. Given that a person suffering from major blood loss is hardly about to go for a run, that person’s blood can be

expanded to bring homeostatic pressure back up to normal. Then, as long as you remain placidly in your hospital bed, there is sufficient red blood to ensure normal respiration. So far so good, but donated blood itself comes with a host of problems. Following the outbreak of Variant Creutzfeldt-Jakob dis- ease (Mad Cow, for the rest of us) in 1996, which caused 170 human cases of the illness, the UK does not use locally donated blood plasma, but imports it from the US. Converse- ly, New York imports about 25 % of its blood supply from Europe. Donated blood is subjected to a plethora of tests, including for sexually transmissible diseases, Hepatitis B and C, and HIV. Then it needs to be typed as A, B, AB, or O and its Rhesus group. This is because, just to spice things up, we don’t all have the same type of blood. Antigens in the blood act to fend off disease by sticking to anything your body doesn’t recognise and so making it ‘bigger’ and signalling for white blood cells to come and 'eat' the invaders. In the middle of a transfusion, a massive supply of alien blood would trigger a

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Chemical Technology • July 2015