Red blood cells

Building blood

Is synthetic blood a reality?

Blood transfusions save lives, but sometimes there isn’t enough in the blood bank or a patient won’t accept the donation (eg because their religious beliefs forbid it).

Helping patients survive with substitutes is tricky. Whole blood does a lot more than transfer oxygen: it contains platelets, which are important in clotting; white cells, which are part of the immune system; and clotting factors in the plasma.

Researchers are trying to create oxygen carriers for blood. Current efforts involve removing haemoglobin from red cells and modifying it to keep it stable. Hemopure, developed in the USA, is a preparation of cow haemoglobin treated to make polymers of the globin subunits.

These float freely in the blood and work more or less like normal haemoglobin until they are broken down, although they may increase blood pressure and raise the risk of a heart attack.

Other approaches include using haemoglobin from outdated human blood encapsulated in an artificial coating and making new blood from stem cells. No artificial haemoglobin-based oxygen carriers are in regular use, but they have been given to a handful of patients who would not normally accept blood transfusions. Jehovah’s Witnesses do not accept blood transfusions, and several owe their lives to these substitutes.

Lead image:

Scanning electron micrograph of red blood cells, clearly showing their biconcave disc shape.

Annie Cavanagh/Wellcome Images

Questions for discussion

  • Should doctors give patients blood against their will and without consent if they need it?
  • Should doctors transfuse children if necessary, even if their parents forbid it?
  • Why might some sportspeople want to use blood substitutes? Should this be allowed?

About this resource


Cell biology, Biotechnology and engineering
Education levels:
16–19, Continuing professional development