Blood transfusions are critical in emergency situations, but on-the-spot care can be tricky. Blood requires refrigeration, after all. But science fiction may one day become reality, because doctors are working to develop artificial, powdered blood cells that can be mixed with water and used in a pinch. 
Dr. Allan Doctor, a professor of pediatrics, biochemistry, and molecular biophysics at Washington University in St Louis, Missouri, said:
“Transfusion medicine is challenged by the limitations arising from storage of red blood cells, which are a living tissue, that must be kept cold, have a shelf-life of only 42 days, and must be used within about four hours of removal from refrigeration.” 
Development of the product, ErythroMer, is in its infancy, but researchers have had success in a proof of concept study in mice. They were able to show that when the synthetic blood was inserted into mice, it was able to deliver oxygen to tissues in the same way as normal mouse blood.
In experiments in rats, the powder – made of purified human hemoglobin proteins coated with a polymer to allow it to be used with any blood type – successfully resuscitated animals who had lost up to 40% of their blood.
“It can be stored in an IV plastic bag that a medic would carry, either in their ambulance or in a backpack, for a year or more. When they need to use it, they spike the bag with sterile water, mix it, and it’s ready to inject right then and there.” 
It will be quite some time before the powder, which resembles paprika, can be used in humans, if that ever becomes possible. The findings need to be replicated on larger animals like rabbits and monkeys before it can be tested on humans, who often don’t react the same way in scientific tests that animals do.
ErythroMer is unlikely to replace full real blood transfusions because it doesn’t remain in the body as long as real blood cells. However, the synthetic cells could be enough to sustain patients in an emergency until they were able to reach the hospital. It could be used by medics in an ambulance, or on the battlefield.
“It’s quite a long road, possibly as long as 10 years, before we have definitive answers whether this will work in people.” 
 Miami Herald