SCNT is an alternative method that may be used to create embryonic stem cells. To date, SCNT has not been achieved successfully in humans to create a human embryonic stem cell line.
SCNT refers to the removal of a nucleus, which contains the genetic material or DNA, from virtually any cell of the body and its transfer by injection into an unfertilised egg (oocyte) from which the nucleus has also been removed.
The newly reconstituted egg is then stimulated to start dividing. After 5-7 days in culture, embryonic stem cells can then be removed and used to create many embryonic stem cells in culture. These embryonic stem cell lines are genetically identical to the cell from which the DNA was originally removed.
SCNT may have applications in the creation of embryonic stem cells which can then be used for the development of patient- and disease-specific cell-based therapies as well as the production of stem cells with specific disease characteristics for research purposes. The use of a patient's own cells for tissue replacement through SCNT may overcome the problem of immune rejection that is a major complication of tissue or organ transplantation today.
SCNT is commonly referred to as therapeutic cloning. The word ‘cloning’ often conjures up images of cloning an individual (reproductive cloning) such as the process used to create Dolly the sheep. Using SCNT to create a human embryo to implant into a uterus is illegal in Australia and many parts of the world. The mainstream scientific community overwhelmingly rejects reproductive cloning, but SCNT may provide an invaluable tool for basic research. However, whilst the technology has been proven in many species it has yet to produce a stem cell line in humans. A major breakthrough occurred in November 2007 when a group of scientists reported that they had successfully extracted stem cells from monkey embryos generated by SCNT.
For more information see
Fact Sheet 1.1 Derivation of Human Embryonic Stem Cells for a diagram explaining SCNT or
Fact Sheet 4 - Therapeutic Cloning.