Du sang à partir de tissu embryonnaire

[Serge]

Les tests cliniques d'ici un an ou deux.

Transfusion breakthrough as human blood grown from stem cells

Mark Henderson, Science Editor

Vials of human blood have been grown from embryonic stem cells for the first time during research that promises to provide an almost limitless supply suitable for transfusion into any patient.

The achievement by scientists in the United States could lead to trials of the blood within two years, and ultimately to an alternative to donations that would transform medicine.

If such blood was made from stem cells of the O negative blood type, which is compatible with every blood group but is often in short supply, it could be given safely to anybody who needs a transfusion.

Stem-cell-derived blood would also eliminate the risk of transmitting the pathogens that cause hepatitis, HIV and Creutzfeldt-Jakob disease (CJD) through transfusions.

Scientists behind the advance said that it has huge therapeutic potential and could easily become the first application of embryonic stem-cell research to enter widespread clinical use. “Limitations in the supply of blood can have potentially life-threatening consequences for patients with massive blood loss,” said Robert Lanza, of Advanced Cell Technology (ACT) in Massachusetts, who led the experiments. “Embryonic stem cells represent a new source of cells that can be propagated and expanded indefinitely, providing a potentially inexhaustible source of red blood cells for human therapy. The identification of a stem cell line with O negative blood type would permit the production of compatible ‘universal donor’ blood.”

Blood comes in four groups, A, B, AB and O, and in two rhesus types, positive and negative, and only some of these are compatible with one another. A person with type A, for example, can donate to people with type A or AB, and receive blood of type A or O. Only O negative blood can be given to any patient.

While there is no national shortage of donated blood in Britain, O negative blood sometimes runs low. It is also used widely in military medicine.

The research also has more immediate clinical promise for efforts to turn embryonic stem cells into other types of tissue, to treat conditions such as diabetes and Parkinson’s.

One of the biggest safety hurdles that must be cleared before stem-cell therapies enter clinical trials is the risk of uncontrolled cell growth causing cancer. Red blood cells, however, do not have nuclei that carry the genetic material that goes wrong in cancer, and thus should not present this danger. “This could be one of the biggest breaks for the early clinical application of embryonic stem cells,” Dr Lanza said. “There is still work to be done, but we could certainly be studying these cells clinically within the next year or two.”

While a few red blood cells have been created from embryonic stem cells before, the ACT team is the first to mass-produce them on the scale required for medical use. They also showed that the red cells were capable of carrying oxygen, and that they responded to biological cues in similar fashion to the real thing. About two thirds had no nucleus, which suggests that they are fully fledged adult red blood cells, and the researchers hope to bring this closer to 100 per cent. Details of the research are published in the journal Blood.

Though embryonic stem cells were used in this experiment, it may be possible to create blood from reprogrammed adult cells, also known as induced pluripotent (IPS) cells. These would circumvent some ethical objections to the use of embryonic tissue.

Independent scientists welcomed the work. Professor Alex Medvinsky, a blood stem cell expert at the University of Edinburgh, said: “The problem with relying on donated blood is that there are always shortages. The ability to generate red blood cells in very large numbers would be a very big thing.”

The Times - August 20, 2008

[h16]

Une super nouvelle.

[Serge]

Il y a une solution plus simple : toute personne hospitalisée doit fournir 450ml de sang ( ou 450 ml en plus du volume de sang qu'elle aurait reçu ) au service idoine. Pas le sien, bien entendu

[A.B.]

Il y a une solution plus simple : toute personne hospitalisée doit fournir 450ml de sang ( ou 450 ml en plus du volume de sang qu'elle aurait reçu ) au service idoine. Pas le sien, bien entendu

Pourquoi pas le sien ? On reproduit bien le sang apres, on pourrait donc avoir une "dette de sang".

[Serge]

Que l'on honore ou pas. Le don doit être fait immédiatement par une personne de son choix, au moment de l'hospitalisation. Quand ma fille a été opérée pour une hernie, j'aurais du donner mon sang quand je lui ai rendu visite à l'hôpital. Et une autre fois quand mon fils a eu la mononucléose, etc. Sans ça, je peux aller me faire voir le jour où il m'arrive quelque chose.

[h16]

Pas bête. Intéressant, même. Étonnant que ce système ne soit pas étendu.

[Serge]

En effet, c'est bien dommage.

[john_ross]

Si un tel système ne voit pas le jour c'est parce qu'il n'est pas possible.

Don du sang

Pour les personnes ayant déjà subi une transfusion sanguine, une greffe d'organe, de tissus ou de cellules, le don de sang n'est pas possible, dans un souci de protection du malade mais aussi du donneur.

Mais il semble que dans certains pays après une transfusion il soit possible après un délais de 4 mois il soit possible de donner son sang comme en Belgique.

Même si le système que vous proposer est techniquement intéressant je ne pense pas qu'il soit souhaitable car il s'agit d'un don nécessitant de divulguer des informations privées et que cela doit être fait par des personnes volontaires.

[Serge]

C'est l'accompagnant qui donne son sang ( les parents dans le cas d'un enfant,… ), pas le patient. On le donne également s'il n'y a pas transfusion, une simple hospitalisation suffit.

Et j'ai donné mon sang récemment… mais pas de données privées ( sauf sur mon état de santé mais c'est normal, il me semble ).