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пятница, 23 августа 2013 г.

Stem cells are a big theme in genetics, genomics and medicine. Potentially they may be one of the keys to practical immortality or to substantial prolongation of life of a person. Stem cells are unspecialized cells, which can turn into cells of any organ of an organism. Potentially, by properly implanting them in an organism, it is possible to repair damaged organs or even to grow some surgically removed organs. There have been several successful experiments with repairing liver, retina and heart muscles.

There are, however, two big problems with research in medical use of stem cells. These cells naturally occur in embryos and do not exist in adult organisms. One problem is moral: many people believe that it is immoral to kill embryos with the purpose of prolonging life of adult or elderly people. The other is technical: stem cells from an embryo are aliens to the organism, in which they are transplanted, and the remote consequences of such grafting are unpredictable.

Therefore scientists turned to attempts to make stem cells out of cells of the adult organism, which needs this kind of treatment. One technique has been around for several years. It is possible to turn normal adult cells into something very similar to stem cells. They are called IPSC – induced pluripotent stem cells. These cells are compatible with the organism of the person, from whom they are taken, and can turn into cells of any organ.

But this transformation takes introduction of several genes into the genome of a normal adult cell. Now this introduction is made with the help of a genetically engineered virus. This is technically a very complicated procedure, and it is also very risky. Cells with an artificial virus introduced into their genome are more likely to mutate, and they may (and sometimes do) turn into cancer cells.

A group of Chinese scientists at the University of Beijing decided to try another approach. They think that it is possible to turn adult cells into stem cells by exposing them to certain organic molecules, which could lock some switches in the genome of an adult cell, which make it specialized, and unlock some other switches, which make it all-purpose.

These scientists have done a massive-scale experiment, in which they tried to apply over 10 thousand different chemicals to cells of adult mice. They programmed those cells to turn green when the proper switches are locked and unlocked and a cell becomes a stem cell. Finally they came up with a list of 7 chemicals. First they apply four of these chemicals, then the other three. And some of the programmed adult cells turned green, about 0.2%. They called these cells CIPSC, chemically induced pluripotent stem cells.

The Chinese scientists implanted those modified cells into fetuses of mice, let them be born and grow into adult mice, and then found these marked cells into different organs, which proved that these cells can become cells of practically any organ.

Many things remain unclear. For instance, why do only 0.2% cells get induced into behaving like stem cells? In what exactly way do these cells differ from stem cells of an embryo? Are these cells stable and will not turn into cancer cells? But still this research is a great advance in the study of stem cells and their medical use.

From the news. July, 2013.

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