Blood created from stem cells

This is a milestone in the search for blood substitutes. Transfused for the first time in humans, red blood cells produced in the laboratory from stem cells have proved as good as natural blood cells. These results, obtained by the team of Professor Luc Douay (Hôpital Saint-Antoine, Université Pierre et Marie Curie, Paris) as part of a partnership with the French Blood Establishment, are published Thursday in the journal Blood, organ of the American Society of Hematology.

With medical advances and an aging population, transfusion requirements are constantly increasing in most countries. Currently, each year, 90 million red blood cells are needed worldwide, and 500,000 people are transfused in France. To prevent the inevitable shortages of years, many researchers have embarked on the challenge of artificial blood. But so far, various attempts have been unsuccessful. Thus, artificial hemoglobin, which after being tested on thousands of patients, proved toxic to the heart, with an increased risk of death by 30% infarction. The publication of these data, in 2008, marked the end of this generation of molecules, some of which were already being marketed.

A world first in humans

It's a different approach, using stem cells, selected by the Douay Pr. In recent years, the preliminary work of his team, a pioneer on the subject, have shown that several types of precursors could be grown and differentiated in the laboratory for red blood cells: cells from cord blood, bone marrow, blood peripheral or embryonic cells or cells IPES - or pluripotent adult stem cells, which provide such rich possibilities as embryonic stem cells.

For this world first in humans, French researchers have used adult stem cells from a stem cell donor for a bone marrow transplant. These were grown in a suitable medium (with a cocktail of growth factors) to promote their proliferation and direct them to a fate of red blood cell. In three weeks, reticulocyte-10 billion last step before the red blood cells, have been obtained. Labeled with radioactive chromium (so that researchers can follow their evolution), these precious cells were injected to the volunteer. There they have completed their maturation and survived as long as natural red blood cells.

The advantages of cord blood

"With this experience, we have established proof of concept, welcomes Professor Douay. The challenge now is to move to an industrial phase ". In fact, this first test was conducted with a sample of 2 ml 10 billion red blood cells when a blood bag represents a volume of 400 ml and 2000 billion cells.

For a large-scale production, French researchers are considering several possibilities, including that of turning to cord blood cells, the proliferative capacity is much higher than adult stem cells. "Our results in the laboratory, a cord blood could generate 50 to 100 red blood cells," says Professor Douay.

The team also on board the optimization of systems compatibility between donors and recipients. "There is not only the ABO groups, says the hematologist. Altogether there are over 300 antigens, but by cleverly choosing, we can cover 99% of needs with only three types of blood. This will be possible starting from adult cells pluripotent stem (iPS). This is the way in which we put the most hope. " If this strategy confirms his promise to the future, it will be, according to Professor Douay, first proposed in polyimmunisés, patients who received transfusions as they have developed multiple antibodies and reject all that blood they are injected. In France, they account for 1-3% of transfused or 25,000 transfusions per year. Until then, blood donations are still needed.