Two people in the U.K. are the first ever to receive transfusions of lab-grown red blood cells.
The pair are healthy volunteers in the "Recovery and survival of stem cell originated red cells" (RESTORE) trial, a one-of-a-kind clinical trial taking place at Addenbrooke's Hospital in Cambridge. The trial will ultimately include at least 10 participants, each of whom will receive a tiny transfusion of about one to two teaspoons-worth of lab-grown red blood cells, according to a statement (opens in new tab).
The goal of the trial is to compare how well these lab-grown cells survive in the body compared with standard red blood cells from a donor. So each trial participant will receive two mini-transfusions — one with standard cells and one with lab-grown — spaced four months apart. The order of the transfusions will be randomized.
Scientists expect the lab-grown cells to survive longer than standard cells, mostly because standard blood transfusions contain cells of varying ages while lab-grown cells can be made fresh.
"If our trial, the first such in the world, is successful, it will mean that patients who currently require regular long-term blood transfusions will need fewer transfusions in future, helping transform their care," chief investigator Dr. Cédric Ghevaert (opens in new tab), a professor in transfusion medicine and consultant hematologist at the University of Cambridge and National Health Service Blood and Transplant (NHSBT), said in the statement.
People who require regular blood transfusions, such as those with sickle cell anemia, face a risk of "iron overload," in which excess iron accumulates in the body and damages organs, according to the medical database StatPearls (opens in new tab). In addition, repeat transfusion patients can also develop antibodies that target specific proteins, or antigens, on the surface of red blood cells.
These antigens distinguish the different blood groups, including the major groups — A, B, AB and O — and the lesser-known minor groups that are challenging to match between blood donors and recipients. When transfusion patients develop antibodies against specific blood groups, this puts them at risk of life-threatening immune reactions and therefore limits the types of blood they can receive in the future, according to a 2018 report in the journal Blood (opens in new tab).
"This world leading research lays the groundwork for the manufacture of red blood cells that can safely be used to transfuse people with disorders like sickle cell," Dr. Farrukh Shah (opens in new tab), the medical director of transfusion for NHSBT, said in the statement. Ideally, the work will not only reduce the number of transfusions such patients need, but also allow medical researchers to grow rare blood cells in the lab.
"The need for normal blood donations to provide the vast majority of blood will remain," Shah said. "But the potential for this work to benefit hard to transfuse patients is very significant."
For the new trial, scientists extracted stem cells from blood donated by adult volunteers and allowed those cells to mature in lab dishes. The stem cells were "hematopoietic," meaning they could only mature into red blood cells, white blood cells and platelets.
The team then ran the mature cells through a filter normally used to remove white blood cells from standard blood donations, CNBC reported (opens in new tab). Finally, they tagged the purified red blood cells with a radioactive marker, so that they could track the cells in the body post-transfusion.
So far, "no untoward side effects were reported" in the two trial participants, according to the statement. After the trial concludes, more research will still be needed before lab-grown blood cells can be widely used. "But this research marks a significant step in using lab grown red blood cells to improve treatment for patients with rare blood types or people with complex transfusion needs," the statement reads.