James Weimann from Weimann JM, Johansson CB, Trejo A, & Blau HM, (2003). Stable reprogrammed heterokaryons form spontaneously in Purkinje neurons after bone marrow transplant. Nature Cell Biology 5, 959-966.
So much sturm und drang has been spent on whether to create new embryonic stems cells for research – vs. “reprogramming” adult stem cells to seek the same ends – that the real promise of stem cell research remains submerged in controversy.*
Clear answers are not yet in on which approach is best. Still, most observers would agree that doing both kinds of experiments is essential. Much is being learned from adult stem cell research that might be applied to cultured embryos, and vice versa.
One of the golden goals of such work is to someday be able to safely replace damaged or ill tissues, or even whole organs. So, do you start with adult stem cells that are already programmed to make a certain cell type, such as renal tissue? Or do you go all the way back to square one, using embryonic stem cells – even totipotent cells – to generate younger, highly specific tissue types that can be used therapeutically? Is it faster and easier to start from scratch? Or might cells that are already “halfway there,” already committed to a certain cell lineage, be a better starting place? Also, might adult stem cells be less immunogenic, less likely to be rejected, when re-implanted into their original, familiar host?
Research hasn’t provided many satisfying answers yet. But the picture may soon change dramatically since federal regulations in the U.S. started being modified to allow creation of new embryonic stem cell lines for research. This change is likely to greatly speed up the pace of experimentation, as will the flow of federal money meant to spur embryonic stem cell work.
The politically motivated restrictions imposed upon researchers limiting research to only use a few already-established embryonic cell lines, plus prohibiting federal funding for most embryonic stem cell research – severely hampered U.S. stem cell experimentation, inadvertently allowing research teams in the United Kingdom, Korea, Japan and elsewhere gain a strong head-start in this new biotechnical industry. Fortunately, some states such as California responded by setting up stem cell research programs of their own – free of federal restrictions hoping to help keep U.S.-based researchers competitive.
In any case, the latest stem cell results coming from The Ellison Medical Foundation scholars show that stem cells of either type – embryonic or adult – are dependent on vital information gleaned from their surroundings. Stem cells, like all other cells, need to know who they are, where they came from and who their neighbors are. In other words, each cell lives in a particular niche, and it’s the flow of “positional” information – via growth factors and other signaling molecules from neighbors, that tells stem cells what they should be doing, even whether to live or die. So science’s important task now is to decode, understand and manipulate all this inter-cellular signaling.
*During the period from the years 2000 through 2008 there were no U.S. federal guidelines for stem cell research. To address this much needed guidance, The Ellison Medical Foundation provided major funding for stem cell guideline development by The National Academy of Sciences and the subsequent formation and operation of The National Academies’ Human Embryonic Stem Cell Research Advisory Committee. The formation of the committee is a result of a recommendation from the EMF supported report on “Guidelines for Human Embryonic Stem Cell Research.” The committee will meet 2 to 3 times a year to monitor and review scientific stem cell research and to produce periodic updates and revisions to the “Guidelines” as needed.