‘Therapeutic cloning’ refers to the formation of embryonic stem cells by Somatic Cell Nuclear Transfer (SCNT). In this process, the nucleus of an animal/human gamete (egg) is replaced with one from a mature cell (e.g. a skin cell) from another animal/individual, leading to the formation of a pluripotent cell with the genetic characteristics of the donor of the nuclear material. This pluripotent cell has the ability to divide and form an embryo. Although it is theoretically possible for an embryo formed through SCNT to develop into a ‘clone’ of the nuclear donor this could only occur if the embryo were to be implanted into a uterus. This is strictly prohibited in Australia, Europe and the USA and has never occurred. It is important to note also that SCNT is an extremely difficult process with a low success rate. The use of pluripotent cells derived from embryos formed by SCNT has very largely been superseded by the discovery in 2006 that it was possible to reprogram ‘adult’ somatic cells to revert to a pluripotent embryonic like cell – these cells are termed induced pluripotent cells and show great promise for future therapeutic and research applications without the ethical concerns raised by the use of embryonic stem cells whether derived from ’excess’ fertilised embryos created by IVF for fertility treatment, or by SCNT.
The ethical considerations around the use of embryonic SC in research and treatment of disease as well as further information about the different types of stem cells, are well laid out in several FACT sheets to be found on the this link to the European Stem Cell Foundation. Secondary teachers and students may also find information on ethical issues in this subject sequence for VCE Biology here.