More Cells are Good, More Diverse Cells are Better
Eleven of the Bush-era human embryonic stem cell lines are of European origin. Of the 40 lines newly approved by the National Institutes of Health, at least 22 are of European origin. Five of the Bush lines are from two gamete donors, and six of the new Harvard University lines are from three donors.
A team of researchers at the University of Michigan analyzed this limited genetic diversity in a paper published yesterday in the New England Journal of Medicine. They investigated 47 lines including 13 of the 21 Bush-era lines and 22 of the 27 newly approved Harvard lines.
The research team estimates that there are about 700 hESC lines available in the world, but that the 47 they investigated are the most widely used. The authors conducted a genotype analysis for the stem cells, looking at 500,000 single nucleotide polymorphisms along each line’s genome. Each of these represents a point in the DNA sequence where notable variations occur. They then compared the cell line genotypes to those of 2,001 subjects from the HapMap Project and Human Genome Diversity Project, which map human genetic diversity around the world. Two of the Bush-era lines, which came from labs in Singapore, are of East Asian origin, and three others were of mixed Middle Eastern and European origin. According to a University of Michigan press release, “none of the lines were derived from individuals of recent African ancestry, from Pacific Islanders, or from populations indigenous to the Americas.”
This unfortunate reality underscores the need for not only expanded hESC research, but also for more diverse research. The Bush-era policy was clearly inadequate and the new policy fortunately allows for much more freedom in conducting research. But if we really want to realize the promise of stem cells, scientists will need to work with lines from diverse genetic origins. That is the only way to design treatments and therapies that work for all populations. Diseases manifest themselves differently in different populations, whether because of genetics or environment. There are also the problems of side effects and treatment effectiveness that scientists can only properly assess when treatments are tailored to specific populations.
Jonathan Moreno and I recently wrote about this very issue as it concerns the Latino community at the Lationvations website.
Michigan’s new Consortium for Stem Cell Therapies plans to attack this issue of limited genetic diversity in the cells head-on by deriving lines that carry the genes responsible for inherited diseases and by also deriving lines from underrepresented groups like African-Americans.
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