Another source of pluripotent stem cells
Stem genitalia
Pyotr Smirnov, "Newspaper.Ru»
From the male testicles, it was possible to isolate cells from which, without any genetic manipulation, any organ of an adult organism can be grown without the risk of rejection. The ladies were unlucky: the cells contained in the ovaries do not have the necessary properties.
With all the successes of biotechnology and tissue engineering in the creation of artificial organs in the very near future, few doubt. But, despite the very promising picture, the main issue – the source of living cells - has not yet been resolved. Optimal, from the point of view of many specialists, germ material cannot be used both for ethical reasons and because of biological safety issues - in any case, these are cells of another organism.
Of course, appropriate genetic manipulations make it possible to overcome all barriers, but it is not yet safe to use the material obtained in this way. This is partly why scientists still continue to look for an adequate "source of youth" in the adult body.
This time, the number one object was the male testicles containing primordial cells that produce sperm during division. As it turned out, they have the property of pluripotency, that is, they are able to transform into all known types of cells of an adult organism. In this sense, they are completely "equal" to embryonic stem cells. Although Thomas Scutella from the University of Tubingen and his German and British colleagues limited themselves to demonstrating only the most basic capabilities of their "wards", scientists have no doubt about the advantage of primordial cells over existing sources for cell therapy.
Stem cells have a lot of advantages – in the long term and therapeutic ones – but until recently, freedom of choice was very limited due to the predetermined fate of individual cells of our body. This is due to the division of the embryo into three leaves during embryonic development. Ecto-, endo- and mesoderm, known for more than a century, give rise to the corresponding tissues, and tissues, combining, form organs.
For example, the skin epithelium and nerve tissue develop from the ectoderm, muscles, blood cells and connective tissue develop from the mesoderm, liver hepatocytes develop from the endoderm. Accordingly, depending on which tissue in an adult organism stem cells will be isolated from, their development will be limited in that direction.
Even the most "promising" multipotent mesenchymal stem cells obtained from the bone marrow turn only into mesodermal tissues: bone, muscle and fat. And it is impossible to get neurons from epithelial stem cells at all.
The fact that the authors of the publication in Nature turned to the testicles is not surprising. After all, it is there that our life is "born" when spermatozoa are formed from primordial cells. Preliminary studies of mouse testicles turned out to be very encouraging, so that Scutella and his colleagues could only repeat successful experiments, but with human material. And they succeeded: from the testicular parenchyma, they isolated cells almost identical to embryonic stem cells. Since the latter can only be obtained from living human embryos, the first advantage of the new method becomes obvious.
As for the potential for transformation into other cell types, and therefore the prospects for clinical use, everything turned out to be successful here, too. Konrad and her colleagues obtained several differentiated lines, in particular, insulin-synthesizing cells of the pancreas, in addition, they demonstrated pluripotency and similarity of their wards with embryonic stem cells. By the way, exactly the same evidence – several differentiated lines – was once presented by the Korean Hwang Woo Suk, who later became scandalized; I would like to hope that this will not happen with Scutella, the scientific community is well taught by the bitter Korean experience.
As with embryonic stem cells, pluripotent cells isolated from the testicles have numerous markers that indirectly indicate their "stem" state. And most importantly, when grown in a cup, they give derivatives of all three mentioned leaves. If labeled primordial cells are transplanted into an embryo at very early stages of development, they even take part in the development of some organs.
But another property imposes some restrictions on future use. The transplantation of several such cells to immunodeficient mice (both human in the current work and mouse in the past) led to the development of tumors-teratomas. In principle, their appearance is also proof of pluripotency, since teratomas differ in that they consist of cells of different germ leaves.
Scientists cannot allow the appearance of any tumors in humans - therefore, experiments are still being carried out only on mice. However, according to scientists, the appearance of tumors is easily avoided if the first stage of differentiation is carried out in a test tube, and cells with an already determined fate are transplanted. Moreover, the "source of eternal youth" turned out to be very stable: all 22 volunteers, among whom there were even patients with minor problems of spermatogenesis, had a sufficient, and most importantly, a constant number of primordial cells.
However, now the team is at risk of being accused of chauvinism, because for reasons of immunocompatibility, only men will be able to take advantage of their achievements.
It is impossible to isolate such cells from the female ovaries, since in the female body the first stage of the formation of germ cells is completed in the embryonic period.
But there are no other restrictions in the first approximation, and it will be possible to get, for example, the retina of the eye or even brain neurons from the testicles.
Portal "Eternal youth" www.vechnayamolodost.ru10.10.2008