Described as a world first, lab-grown red blood cells have been transfused into people for a clinical trial in the United Kingdom.

Known as the , the joint initiative between National Health Service Blood and Transplant (NHSBT) and the University of Bristol, along with the University of Cambridge and other organizations, used blood cells grown from donated stem cells.

A small amount of this blood — between five and 10 millilitres or one to two teaspoons — was then transfused into two volunteers.

It's a process that has been about 10 years in the making, Ash Toye, a professor of cell biology at the University of Bristol and NHSBT principal investigator, told Â鶹´«Ã½ Channel on Tuesday.

He said while it will take about a year for the data to come in, no adverse events have been reported and the blood has performed as well, and as safely, as it possibly could.

If proven safe and effective, researchers say the lab-grown blood cells could help treat people with blood disorders, such as sickle cell, and rare blood types — who often have difficulty finding well-matched donors.

"The ideal thing here is that effectively, you can take blood from any donor and grow that blood up from the stem cells," Toye said.

"So if the donor is a rare donor, we can basically extend their gift as a blood donor and grow more cells from the initial donation, and this means we get more rare blood."

The researchers say that if manufactured cells do last longer in the body, patients would not need transfusions as often as they otherwise would.

Moving forward, at least 10 participants will receive two mini-transfusions at least four months apart. One transfusion will be standard donated red cells and the other will be lab grown.

"We hope our lab-grown red blood cells will last longer than those that come from blood donors," chief investigator Cedric Ghevaert, professor in transfusion medicine and consultant hematologist at the University of Cambridge and NHSBT, said in a statement.

"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."