Stem cell extraction from body cells
Differentiated cells, i.e. cells of a tissue that are fixed in development, can be reprogrammed by making a few changes to their genetic material in such a way that any tissue can arise from them again. The pluripotent cells produced in this way resemble embryonic stem cells in their appearance and properties. These findings from two researchers at Japan's Kyoto University could revolutionize stem cell research.
Kazutoshi Takahashi and Shinya Yamanaka introduced 24 genes into the connective tissue cells of adult mice that are normally only transcribed in embryonic stem cells. The genetically modified fibroblasts now produced proteins that brought the cells back into the embryonic state. A combination of just four of these proteins, called Oct3/4, Sox2, c-Myc and Klf4, was enough.
When the scientists transplanted these "induced embryonic stem cells" under the skin of mice, they developed into tumors. The growths contained a variety of different tissue types. Injected into mouse blastocysts-a very early stage of development from which regular embryonic stem cells are derived-the induced stem cells helped the embryo mature.
Yamanaka emphasizes that human stem cells show promise for the treatment of a range of diseases, including Parkinson's disease, spinal injuries and diabetes. The ethical conflicts and problems with the rejection of foreign cells and tissues could be circumvented by producing pluripotent cells from one's own tissue. However, his results would have to be confirmed in human cells. It is also not entirely clear whether the induced stem cells really share all the characteristics of embryonic stem cells. In addition, one of the proteins, c-Myc, would be found in many types of cancer, which could make the use of these cells critical.
