Pluripotent stem cells: another source
The simplest possible way to obtain stem cells has been foundDmitry Safin, Compulenta
Experts from Germany have managed to turn mature cells taken from the testes of mice into pluripotent stem cells (PSCs) without resorting to artificial introduction of new genes and the use of viruses.
The unusual properties of cells found in mammalian testes were first documented in 2004 by a group of Japanese researchers led by Takashi Shinohara. Scientists experimenting with newborn mice found that certain types of cells from their sex glands have the ability to differentiate in several different directions, repeating the characteristics of embryonic stem cells. Two years later, another scientific group reported the discovery of similar cells in adult mice, and more recently – last year – specialists from the University of Tübingen (Germany) isolated such cells from human male sex glands. "It may seem that the fact of the presence of UCS in the testes of humans and mice is reliably established," says one of the authors of the work in question, Hans R. Schöler from the Institute of Molecular Biomedicine. Max Planck. "However, very often it is not so easy to determine which type of cells is being discussed in the publication, and the capabilities of these cells are described very vaguely."
The emergence of the problems characterized by the scientist is easy to explain. Firstly, there are many different cells in the testes, and a thorough analysis is required to accurately determine the type of samples studied. Secondly, experts have not yet come to a consensus on how to assess the ability to differentiate: what one group will call pluripotence, for the other will be just a sign of limited "multipotency".
In their work, German scientists have tried to eliminate any element of uncertainty. For the study, so-called germline stem cells (germline stem cells) were selected from the testes of adult mice, the only function of which is the formation of spermatozoa. The advantage of these cells is that when cultured in the laboratory, it is possible to obtain a cell line with stable characteristics; the property of unipotence will persist for several months or even years.
Unipotent germ stem cells (emit a green glow) in the testes of a mouse (Kinarm Ko image).
The authors, however, managed to create such parameters of the microenvironment in which part of the cells after a certain time spontaneously "returned" to the embryonic state. "We placed about 8 thousand cells in each well of the culture tablet, and a small part of them was invariably "reprogrammed" after two weeks," says Kinarm Ko, a colleague of Mr. Scheler. At the same time, the process of reproduction of reprogrammed cells, as reported, proceeded much more intensively than in the original line.
As proof, the scientists presented the results of many different experiments. On the basis of reprogrammed cells, hepatocytes (liver cells), neurons and endothelial cells were obtained. Using them, the authors also grew a chimera mouse consisting of genetically heterogeneous tissues.
Scientists cannot yet answer the question about the possibility of using the described technology to obtain pluripotent human stem cells.
The full version of the researchers' report is published in the journal Cell Stem Cell.
Prepared according to the materials of the Society for Scientific Research named after Max Planck.
Portal "Eternal youth" http://vechnayamolodost.ru09.07.2009