International Society for Stem Cell Research Recommendation for a Revised Nomenclature

This statement was prepared by an International Society for Stem Cell Research (ISSCR) task force and approved by vote of the ISSCR Board of Directors and membership. ISSCR is a nonprofit professional society comprised of scientists and ethicists representing a broad range of opinions and specialties dealing with stem cell research.

The inaccurate use in various public and scientific venues of various terms dealing with the production of stem cell lines by the transfer of body cell (somatic) nuclei into enucleated eggs of the same species, and the negative connotation of the commercial term ‘therapeutic cloning'; make a change in terminology necessary. The aim of this terminology change is to provide accurate, standardized terminology that will facilitate frank scientific, ethical and public debate on stem cells and their potential for medicine.

ISSCR encourages its members and the scientific press to use these terminologies in publications, presentations and communications. This will introduce scientifically accurate terminology into scientific as well as general literature and language.

This statement addresses two commonly used descriptors in stem cell research:

1.  The production of stem cell lines by the transfer of body cell (somatic) nuclei into
     enucleated eggs of the same species, commonly referred to as “ therapeutic 
     cloning ”.

• The ISSCR supports and endorses the use of the term “nuclear transfer” in place of “therapeutic cloning” to refer to the production of stem cell lines by the transfer of body cell (somatic) nuclei into enucleated eggs of the same species. Nuclear transfer is abbreviated as “ NT ”. Cells created by nuclear transfer should be described as “ NT stem cells ” or “ NTSC ”.

The term “cloning” does not accurately describe this biological process. Cells generated by nuclear transfer are by no definition a clone of the donor of the transferred nucleus, as the enucleated oocyte still contains numerous stable maternal proteins that are transmitted for several cellular divisions and could impact on gene expression, numerous types of maternal RNA, as well as maternal mitochondrial DNA. It is known that at least some of these molecules impact significantly on expression of the incoming transferred genes, for example, converting somatic cell genomes (such as skin subsets committed to skin specific gene expressions) to pluripotent cells. Mitochondrial genes are highly sequence diverse, and the interaction of nuclear genes/products with mitochondrial genes/products introduce even higher combinatorial diversity, and so no scientifically based assertion can be made as to the ‘clonality' of the cells produced through nuclear transfer. The term “therapeutic cloning” as used to describe all stem cells generated through nuclear transfer is therefore scientifically erroneous and misleading.

The term “therapeutic” is equally misleading. While the stem cell research community is dedicated to the search for therapies using the technique of nuclear transfer, it is far too early to predict therapeutic uses, and naming a technique for its hoped outcome may inadvertently offer premature hope to desperate patients and families.

2.  Human embryonic stem cells derived from pre-implantation blastocysts produced
     by sperm-egg fertilization, commonly referred to by a variety of acronyms.

Posted September 27, 2004