Blood transfusions are an important way to replace lost blood, often saving lives in the worst possible circumstances. But not everyone can get this procedure, because some patients with rare blood types do not meet the requirements.

NHS UK announced that it has started a clinical trial in which researchers will inject patients with red blood cells grown in the laboratory. This is the first time they will be transfused into another person as part of a blood transfusion study.

The study, called RESTORE, is a joint research initiative between NHS Blood and Transplant (NHSBT) and University of Bristol, as well as various researchers from the University of Cambridge.

In an NHS YouTube video, University of Bristol researcher Ash Toye explains that RESTORE is a clinical trial designed to assess whether red blood cells grown in a laboratory are similar to, or perhaps even better than, a donor’s own blood cells produced in body

Now these cells are not just prepared in a laboratory from scratch. These are erythrocytes grown from human blood stem cells, namely CD34+ cells isolated from the blood of an adult donor. (Donors were recruited from the NHSBT blood donor database). Using stem cells allows researchers to virtually conjure up any type of blood cell they need, with the hope that it won’t be rejected by the body.

As Toye explained, laboratory-made blood was previously transfused through an autologous transfusion, in which researchers used a donor’s stem cells and then injected the laboratory-grown red blood cells back into the human body. But this is the first time it has been given to another person, a process known as an allogeneic transfusion.