Somatic-cell nuclear transfer
The somatic cell nuclear transfer referred to in the genetics of the transfer of a nucleus in a coreless cell for the purpose of cloning. The somatic cell nuclear transfer is a form of asexual reproduction and one of the three methods for the generation of induced pluripotent stem cells. The somatic cell nuclear transfer is among the only method to produce pluripotent stem cells from dead tissue, such as frozen or lyophilized tissue.
Principle
The nucleus of a cell comprising the DNA of an organism, which is used as a template. Upon removal of the nucleus of a cell and replacing the same with a nucleus of another cell, the presentation of a cell is transmitted on a different one. The cell and all cells that are derived from it by cell division, hence change.
Problems
Since the stress on the cell and the nucleus are enormous, this process results in a high mortality rate for the recipient cells. This process can not be automated and must be performed manually under a microscope, which is very expensive at present. The discharge rate is low due to incomplete epigenetic reprogramming in the oocyte. Errors occur frequently in the formation of the placenta, such as Placentomegalie, decreased vascularization, hypoplasia of trophoblastic epithelium and an above-average fetal growth.
Because the donor cell is a body cell, it must be artificially "activated" in order to work as a fertilized egg can, because they will then grow into a whole organism. The leading to the activation of biochemical processes are far from being completely understood.
History
A cell nuclear transfer was the first time in 1895 contemplated by Yves Delage. The methodological approach was proposed in 1924 by Hans Spemann. In 1935 he received the Nobel Prize in Physiology or Medicine, and in 1938 he expanded his methodological proposals for the last time. However, the methods were sufficiently developed until 1952, as a transfer of cell nuclei of embryonic cells in frogs by Robert Briggs and Thomas J. King was. John Gurdon was able to show the complete reprogramming of transplanted nuclei, that is, from the differentiated cells were induced pluripotent stem cells are obtained, from which all cell types were able to develop. In 2012, John Gurdon of the Nobel Prize in Physiology or Medicine was awarded.
The first publication of a somatic cell nuclear transfer in mammals was made in 1981 by Karl Illmensee. However, these results could not be reproduced. The cloned by Keith Campbell and Ian Wilmut of Dolly the first known case of a cloned mammal introduced in 1997 dar. However, it was proved by Rudolf Jaenisch, that in enucleated donor oocytes existed no genetic information and only in 2002 the reprogramming of the transplanted nucleus was performed.
On May 15, 2013 were reported in Cell that it was the first time succeeded in the way of nuclear transfer to win pluripotent human stem cells and develop into specialized cells of the pancreas and blood, heart, liver and nerve cells.