Stem cells labeled "extra pure"

The stem cell bank will fit in a spoonAlla Solodova, Infox.ru

For the first time in the half-century history of studying stem cells, biologists have isolated the "purest" population of hematopoietic cells. Just one such cell can form all kinds of blood cells. The researchers are confident that a little more, and they will be able to "keep stem cells in a tight grip", manage the regenerative potential of cells and put a bank of cord blood in one tablespoon.

What cells do doctors need

All cells of an adult organism are "born" from one progenitor – a zygote. She and her descendants of the first generations – embryonic totipotent stem cells – give rise to cells of different organs and tissues. If scientists had such universal cells, they would be able to realize the most unusual scientific ideas. But the problem is that few and undifferentiated totipotent (embryonic) stem cells are present only at the early stages of embryogenesis. As the embryo develops, such cells gradually disappear.

Pluripotent, multipotent and unipotent stem cells are preserved in different amounts in the adult body. The former can give rise to most cell lines. Multipotent ones are more specialized, so they are not suitable for every organ or tissue. Unipotent cells are stem cells that are in the final stages of differentiation. Their fate has already been determined – they develop into cells of specific lines.

Most of all, doctors and researchers are interested in pluripotent stem cells. After all, it is from them that the largest "assortment" of final products – cells and tissues - is obtained.

Blood Family Tree

However, doctors store a small number of almost universal cells in cord blood banks. But these "deposits" are not "clean". This is a "cocktail" of stem and non-stem cells that are at different stages of differentiation and maturation. This means that by transplanting such blood, doctors inject patients with both stem cells and "ballast". However, ballast (differentiated) blood cells do not harm. On the contrary, they support the patient's life during the period when stem cells are just turning into blood.

"The hierarchy of progenitor cells, from which adult blood cells are formed, is very complex, branched - it looks like a tree. It has roots – self–renewing hematopoietic stem cells that constantly replenish the bloodstream with their "sprouts and leaves" – shaped elements of blood," explains the correspondent Infox.ru John E.Dick is the head of a new work, as a result of which scientists have dug to the roots of the blood family tree.

In a healthy person, about a third of a trillion new "leaves" are "blooming" on the blood tree every day. And they all come from the bone marrow, in which hematopoietic stem cells (HSCs) are concentrated and self-renewing.

But such cells are quite difficult to isolate from the "cocktail" of umbilical cord blood or human bone marrow. "It's like trying to find a needle in a haystack," John Dick continues, answering the correspondent's questions Infox.ru "To catch one hematopoietic stem cell–the root of all hematopoiesis– we had to "filter out" about two hundred thousand umbilical cord blood cells."

Search for a universal cell Of course, John E.Dick from the University of Toronto and his colleagues "filtered" the cells not through a sieve.

They used a fairly common method of flow cytometry. "We have cleared the stem cells from the "ballast". With a tablespoon of such cells, you can replace the "deposit" in the cord blood bank," explains John Dick, "Because there are "mixes" of cells stored there, most of which have already begun to specialize."

Biologists have not just isolated cells, but also described some molecular features that are characteristic of stem cells. They, although partially, but still prescribed a molecular genetic specialization route.

Now scientists plan to continue their research and fully draw a molecular portrait of the universality of the hematopoietic stem cell.

"If we manage to do this, then we will be able to control stem cells – we can say that we will learn to train them," continues John Dick. "You see, it is important to understand thanks to which molecules and genes the stem cell retains its primordial nature, why it does not completely or partially lose its universality."

More information about the progress and results of the study can be found in the article published in Science (Notta et al., Isolation of Single Human Hematopoietic Stem Cells Capable of Long-Term Multilineage Engraving).

Portal "Eternal youth" http://vechnayamolodost.ru08.07.2011