Two American research teams, using two different techniques, have succeeded in creating blood stem cells.
“This is the holy grail”. Mick Bhatia, a Canadian researcher specializing in stem cells, dares to use the expression to qualify the results obtained by two independent teams from Boston Children’s Hospital (BCH) and Cornell University (United States). They both succeeded in creating blood stem cells, capable of producing red blood cells, platelets, and even immune cells. The important elements for synthesizing artificial blood.
“For years, parts of the recipe have been identified, but no one had gone that far,” he adds in an editorial of the magazine Nature which accompanied the publication on Wednesday of the two studies. This is the first time that researchers have succeeded in passing all the stages. “
Cell reprogramming
George Daley’s BCH team created human cells that behave like blood stem cells, but are unlike what you can find in nature. Starting from conventional cells, in particular taken from the skin, the first step consisted in transforming them into induced pluripotent stem cells (iPS), a primary stage of cellular development artificially recreated. They can then differentiate into many other types of cells. It was the easiest step.
It was afterwards that the real feat was achieved. After adding seven transcription factors, which allow certain targeted genes to be expressed in cells, they were able to differentiate it into blood stem cells. They then introduced these modified human cells into mice, in order to observe their evolution. And in twelve weeks, they produced all the cells in human blood.
Saved mice
On their side, Shahin Rafii and his Cornell team may have done even better. They managed to create real blood stem cells, without going through iPS reprogramming. They took samples from vessels and used four transcription factors added to the cells removed. By growing them in Petri dishes mimicking the blood environment, they differentiated into blood stem cells, and multiplied.
They even saved mice that had been irradiated, and whose blood cells had been destroyed. The researchers’ creations regenerated them all, even immune cells, allowing rodents to reach the end of their laboratory life expectancy, roughly a year and a half.
These two major breakthroughs open the door to laboratory production of blood stem cells, which could serve, at least initially, as alternative therapies to bone marrow transplantation in patients with leukemia, or other heart disease. blood.
Duel of champions
Stakes which do not prevent the two research teams from engaging in a small game by interposed declarations, pointing out the flaws of the other method. Shahin Rafii got his results without going through the iPS step. For him, his approach would be more efficient, and he compares it to a direct flight from one point to another, while that of his competitor would make “a little detour by the moon”! He adds, moreover, that the more transcription factors are added, the more non-receptive cells must be discarded, and the greater the risk of mutations, and therefore of tumors, are important.
Far from being impressed, George Daley retorts that of course, his method can be made more efficient, and less mutagenic, but that it has the advantage of using simple cells to take, especially from the skin, while the samples of his colleague turn out to be much more complicated.
The future will tell us which method will emerge. But in both cases, these major breakthroughs pave the way for a multitude of applications, from alternatives to transplantation to the cultivation of blood products. They also remove the frustration of researchers who, for more than 20 years, have tried in vain to create artificial blood.
.