That’s what scientists in the UK are striving for anyway — they are researching the possibility of synthesizing human blood using stem cells, the result being in theory an unlimited supply of o-negative blood for transfusions.

The blood should be free of infections like the human form of mad cow disease.

Teams will test human embryos left over from IVF treatment to find those destined to develop into the universal “O-negative” blood donor group.

O-negative blood can be transfused into anyone without fear of tissue rejection and is the only safe option when a patient’s blood group is unknown or not immediately available.

This precious blood is in limited supply because only 7% of the population belongs to this blood group.

Go science. From BBC.