Stories have appeared in the media recently touting the wonders of adult stem cell research, and while adult stem cells are technically pluripotent [a cell that can generate more than one kind of cell when it reproduces], their germinating ability so far is type-limited. For example, an adult stem cell in the skin can produce several kinds of skin and hair cells, and an adult stem cell in the lateral ventricle of the brain can generate neurons for olfactory circuits, and some glial cells. But a skin cell cannot become a brain cell.Furthermore the ban on stem cell testing can be really dangerous for clinical trials and the people who could benefit from the drugs:
So a simple discomfort with the use of one kind of human cell (which does not extend to some questionable genetic altering of animals to be used for testing) delays the development of lifesaving drugs and increases clinical trial risks. It's always frustrating when it seems obvious that the right is obsessed with stem cells and fetuses, but fail to step back and look at the suffering of adult humans.
Once they determine a positive, measurable effect, the drug leads are then tested on more sophisticated, animal cell-based models that represent some aspect of the target disease. With every round of elimination, the funnel’s opening grows smaller until those thousands of compounds have narrowed to, say, ten potential drugs. Those drugs are then tested on animals that, in most cases, have been inoculated with the target disease. After the initial testing and refinement process—which can take years—researchers are finally ready to administer the drugs to humans in clinical trials.But there is one catch. These drugs have never been proven on human cells. And drugs that work on animal models of disease can fail in human trials. If researchers could jump ahead and use embryonic stem cells at the level of cell-based testing, Croft notes, “they would know, at a very early stage, that drug candidates worked on the specific types of human cells affected clinically. Research costs and time could, accordingly, drop.” In addition, cell-based drug testing requires millions of cells. Using embryonic stem cells, a lab could generate millions of exact copies, without relying on closely replicated mouse cells. The difference between exact and close is a chasm in the controlled world of the laboratory. Thus, cell type specificity, species specificity, and unlimited numbers are important reasons for pursuing hESC research.