Last week’s issue of Nature included an editorial on “avoiding the chimera quagmire, focusing on the question:
Researchers need to take the initiative in addressing a controversial and urgent ethical issue: under what circumstances should the fusion of cells of animals and humans be permitted?
Certainly the primary research organizations that guide scientific research must set guidelines to the ethical limits of what research is conducted – and at least here in the States, the National Academies of Science has a strong tradition in doing so. The need for ethics regulations must be tempered, however, by minimizing limits on intellectual curiousity. As few limits on what research is permissible should ideally be placed on the scientists as possible, so long as there is a rigorous funding review process, justifying such research. That said, on to the research in question…
In the United States, the National Institutes of Health does not fund research involving the transplantation of human embryonic stem cells into animal embryos. In Canada, this funding restriction extends to the transplantation of human tissue-specific (or ‘adult’) stem cells to animal embryos. In 2005, the US National Academy of Sciences stated its opposition to research in which human embryonic stem cells are introduced into non-human primate blastocysts (pre-implantation embryos), or in which any embryonic stem cells are introduced into human blastocysts, as well as the breeding of any animal into which human embryonic stem cells have been introduced.
At present, such guidelines are reasonable but do not consider several promising and arguably necessary avenues of research that combine human cells or cellular components with other species. These include combining the genetic material of humans and other species, the prenatal combination of cells from different individuals (animal to human, human to animal, or human to human), or grafting tissue from humans to animals.
One troubling outcome of a debate could be UK restrictions on current work combining factors from animal eggs (which, unlike human eggs, are readily accessible) with animal or human nuclei. These ‘nuclear reprogramming’ experiments aim to identify components of the egg that are capable of transforming an adult cell into one with the vast capabilities of stem cells. They could generate stem cells and tissues genetically and immunologically matched to patients, and obviate the need for human eggs and embryos in generating human embryonic stem cells. There are strong arguments for permitting such research, given the minimal safety risk or violation of human dignity when any resulting embryos are arrested at an early stage.
I fear that the mere mention of such animal-human chimeras might stir up religious and ethical concerns amongst the lay public, well before researchers have a chance to explain the details of it. Similarly, with the announcement last week of stem cells discovered in amniotic fluid, I fear that the political debate on behalf of embryonic stem cells will be relaxed, even forgotten. In reality, meanwhile, ethical concerns surrounding these areas of research are minimal, being addressed internally within the major scientific institutions, and offer tremendous benefits to biomedical understanding. That this is even an issue is, in my opinion, largely due to the pernicious agenda of fundamentalists and anti-intellectuals.
Indeed, this editorial concludes with simple and prudent researchers to address all of the questions at hand – ethical and scientific alike:
Scientists should identify the various research protocols defining interspecies research involving human cells and embryos, and the associated risks, ethical issues and benefits of each. They should put forward clear and comprehensive recommendations to the public and to regulatory bodies. If they don’t, they risk having regulation and funding restrictions imposed on their research that are out of proportion to the ethical or safety risks involved. Even worse, they could face prohibitions that lump together research with vast disparities in intent and in the balance of risk and benefit — ultimately penalizing those who stand to gain from the therapies that might emerge.