We’ve reached the point where we can now replace so much of the human body, from bionic eyes and prosthetic limbs to artificial hearts, yet real blood is still required from human donors. Then there’s the problem of hospitals never getting enough of the stuff, especially in every type. That’s why scientists have been working for decades to come up with a substitute and it now looks like they’ve found a breakthrough. Scientists from the universities of Bristol, Cambridge, and Oxford have successfully created synthetic blood using stem cells and they’ve gone on to develop their work to the point that they’ve started human trials. The hope is that this synthetic blood won’t just be able to treat specific conditions and illnesses, like sickle cell anemia, but it could also be used in transfusions for people with rarer blood types.