8 / 40
Chemical Technology • July 2015
6
In pursuit of the
perfect blood
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
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.
by Gavin Chait