This paper addresses the issues, scientific, ethical and legal, surrounding the production of cytoplasmic hybrids (cybrids). Cybrids normally have the nucleus from one individual (animal or human) and the cytoplasm containing mitochondria from another (same or different species). In the press there has been much discussion on the production of animal-human cybrids for therapeutic stem cell transplantation. This paper uses work carried out in animals to show that there is little chance that scientists would use this technique to produce cybrid individuals. Nevertheless, legislation must be in place to ensure that such technologies are both discussed and well-regulated. Recent reports suggest that cybrids of animals and humans which held much promise for the production of stem cells for therapy will not be useful due to problems of compatibility. However, somatic cell cybrids have found a niche in the analysis of human mitochondrial disorders and present few problems in this context. The paper ends with a brief review of the production of “normal” babies to mothers with mitochondrial defects that are cybrids with nuclear and mitochondrial DNA from two different human sources. |