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Controversies |

The Ethical Validity of Using Nuclear Transfer in Human Transplantation

Robert P. Lanza, MD; Arthur L. Caplan, PhD; Lee M. Silver, PhD; Jose B. Cibelli, PhD; Michael D. West, PhD; Ronald M. Green, PhD
JAMA. 2000;284(24):3175-3179. doi:10.1001/jama.284.24.3175.
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Therapeutic cloning (or cell replacement by means of nuclear transfer) is a new biomedical technology that has the potential to transform medicine. Therapeutic cloning involves the transfer of the nucleus from one of the patient's cells into an enucleated donor oocyte for the purpose of making medically useful and immunologically compatible cells and tissues (Figure 1).1 Although the phrase "therapeutic cloning" has been most widely used in this context, we believe that it is misleading. "Cloning" brings to mind images of the replication of a single genome for reproductive purposes. In therapeutic cloning, however, no such replication is involved. For this reason, we prefer the term "cell replacement through nuclear transfer" (CRNT). In this article, we use both terms so that readers may become accustomed to the more technically accurate terminology. Moreover, because therapeutic cloning requires the creation and disaggregation ex utero of blastocyst stage embryos, this technique raises complex ethical questions.24 While these questions must be addressed and understood, we believe that a counterbalancing and stronger ethical case can be made for therapeutic cloning research.

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Figure. Procedure for Therapeutic Cloning
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A somatic cell from the patient is electrofused with an enucleated donor oocyte. Pluripotent stem cells are isolated from the inner cell mass of the resulting blastocyst and then differentiated in vitro into genetically matched cells for transplantation. The cells also can be reconstituted into more complex tissues and organs using tissue engineering techniques.



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