Why do blood platelets have no DNA

Platelets multiply by themselves

Platelets are the smallest blood cells. They have a life expectancy of nine to eleven days and during this time they primarily perform one task: closing wounds. To do this, they either attach themselves to the edges of an injured area or lie together to plug the leak, so to speak. Because of this function, the blood platelets are also considered to be key factors in various blood clotting disorders: If the platelets are not active enough or there are too few, bleeding can occur. If, on the other hand, they get out of hand, it can lead to undesirable clumping and thus to strokes, for example.

Since the platelets do not have a nucleus and? apart from the genetic material in your cell power plants, the mitochondria? do not have DNA, they have so far been denied the ability to reproduce. However, when Schwertz and his colleagues observed isolated blood platelets in the laboratory, they were surprised: after just six hours in the culture bottle, around five percent of the platelets formed long, thread-like growths on which new cells grew like pearls on a string. These new platelets did not differ in size or biochemical properties from the parent cells, further tests showed. Their functionality also seemed to be completely identical. In addition, the new platelets formed not only under the original laboratory conditions, but also in a whole blood container and even in platelet samples that had been stored for a long time and were intended for a transfusion.

The researchers have not yet been able to prove that platelet replication also takes place in the bloodstream itself. However, they think this is very likely as the same phenomenon occurred under very different conditions. It would also explain how the very limited number of hematopoietic stem cells in the bone marrow manage to maintain the large platelet population in the blood.

Hansjörg Schwertz (University of Utah, Salt Lake City) et al .: Blood, doi: 10.1182 / blood-2009-08-239558 ddp / Wissenschaft.de - Ilka Lehnen-Beyel
January 28, 2010

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