Ethics and Stem Cell Testing
McKhann, Guy, Clinical Psychiatry News
As scientists move forward with their research on human neural stem cells, we must look ahead to how we can test these potential therapies in an ethical manner.
Recently I was a member of a multidisciplinary working group that examined these ethical issues over the course of a year.
Our work, which was published in the July 15 issue of Science, focused on the moral issues surrounding human to nonhuman primate neural grafting.
As a result of our work, we proposed six factors that review panels should consider when evaluating research that involves the use of human neural stem cells in a primate.
The six factors are the proportion of engrafted human cells, neural development, the nonhuman primate species, brain size, site of integration, and brain pathology.
This framework is aimed at minimizing the risk that this type of human to nonhuman primary testing would result in giving human characteristics to the primates, which raises numerous other moral issues.
But the first question to consider is why would you want to do this type of interspecies research at all? Why not simply perform experiments in mice using mouse stem cells?
The answer is that there is so much that we don't understand about the human brain and how these stem cells might impact it.
For example, we don't know how stem cells will develop into neurons or how we can keep stem cells from becoming other types of unwanted cells, such as tumor cells.
Therefore, we need to find an animal model that is as close to the human brain as possible. A primate model would allow us to gain much more information before proceeding with human trials.
In my view, this is a logical and ethical course to take.
The next issue to consider is whether this research would humanize the primate.
Our working group concluded that researchers would need to consider the number of cells being grafted and the degree of maturation of the primate. …