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Cloning: Therapeutic vs. Reproductive1. What is cloning? In general, cloning is the process of creating an identical copy of something. In science, there are many different kinds of cloning, most of which are now commonplace. Cloning is the creation of multiple copies of a single molecule, cell or virus. Genes are routinely cloned by scientists and many of the newer medicines that have been created, such as the insulin that diabetics must take, were made through gene cloning. Cloning has allowed scientists to develop powerful new drugs and to produce insulin and useful bacteria in the lab. 2. What are therapeutic cloning and reproductive cloning? Therapeutic cloning, or somatic cell nuclear transfer (SCNT), is the cloning of cells. This involves removing the nucleus from an unfertilized egg and replacing it with the nucleus of a “somatic cell” (an adult skin cell, for example). Given the proper signals, this single cell can be tricked into starting to divide, much like an embryonic stem cell. For example, SCNT could be used to create a line of embryonic stem cells genetically identical to the donor with health problems. Healthy versions of the sick cells could be engineered and used to treat the sick donor without risk of their body rejecting the cells. The American Association of Medical Colleges (AAMC) supports ongoing research into SCNT and has endorsed legislation that would allow such research to flourish. Until recently, nuclear transfer or therapeutic cloning was the only way that scientists imagined it would be possible to develop patient-matched cell lines. However, since iPS technology has made it possible to derive patient-specific pluripotent lines by reprogramming adult human cells, and since it has never been possible to do nuclear transfer successfully with human eggs, SCNT may no longer be relevant as a method to derive stem cells. Reproductive cloning, on the other hand, is intended to create a duplicate of the source of the nucleus, for example Dolly the sheep. Human reproductive cloning, which is highly unethical, would be an attempt to duplicate a human. In theory, a blastocyst would be created and then implanted in a womb to result in a pregnancy. The overwhelming consensus of the U.S. scientific and medical communities, including the AAMC and the National Academy of Sciences, is that reproductive cloning should be banned [Source: American Association of Medical Colleges]. The International Society of Stem Cell Researchers (ISSCR) agrees. |
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