Potentiality of embryonic stem cells: an ethical problem even with alternative stem cell sources
- Correspondence to: H-W Denker Institut fuer Anatomie, Lehrstuhl fuer Anatomie und Entwicklungsbiologie, Universitaetsklinikum Essen, Hufelandstr. 55, 45122 Essen, Germany;
- Received 13 October 2005
- Accepted 6 April 2006
- Revised 27 March 2006
The recent discussions about alternative sources of human embryonic stem cells (White Paper of the US President’s Council on Bioethics, 2005), while stirring new interest in the developmental potential of the various abnormal embryos or constructs proposed as such sources, also raise questions about the potential of the derived embryonic stem cells. The data on the developmental potential of embryonic stem cells that seem relevant for ethical considerations and aspects of patentability are discussed. Particular attention is paid to the meaning of “totipotency, omnipotency and pluripotency” as illustrated by a comparison of the developmental potential of three-dimensional clusters of blastomeres (morula), embryonic stem cells, somatic or (adult) stem cells or other somatic (non-stem) cells. This paper focuses on embryoid bodies and on direct cloning by tetraploid complementation. Usage and patenting of these cells cannot be considered to be ethically sound as long as totipotency and tetraploid complementability of embryonic stem cells are not excluded for the specific cell line in question. Testing this poses an ethical problem in itself and needs to be discussed in the future.
↵i (comprising (i) “organismically dead embryos”, 6–8-celled IVF embryos that ceased dividing; (ii) blastomeres obtained by non-harmful biopsy of living embryos; (iii) “biological artifacts”, genetically modified cells/embryos lacking certain properties needed for early development or implantation (eg, a gene that is necessary for trophoblast differentiation), but which may later be reactivated after embryonic stem cell production (method: eg, “altered nuclear transfer” to an oocyte); (iv) reprogramming human somatic cells, for example with the aid of special cytoplasmic factors obtained from oocytes).
This work was supported by Kompetenznetzwerk Stammzellforschung NRW.
Competing interests: None.