Slashdot Mirror
Human Limb Regeneration a Possibility?
SablKnight writes "This NY Times article (free reg. req.) says maybe. Apparently research is being done in parallel with the more controversial stem cell implantation to attempt to regenerate missing parts in humans. Though this has been a subject of mild interest for centuries, serious research started much more recently, when an experiment involving mice suffered a setback. 'A few years ago, Dr. Ellen Heber-Katz, an immunologist at the Wistar Institute in Philadelphia, was conducting an experiment with those mice, which develop a disease similar to lupus. As is common, Dr. Heber-Katz punched a pattern of holes in each mouse's ear to so she could tell which mouse was which. Three weeks later, she said, when she checked on the experiment, 'there were no ear holes.'' A quick google search reveals similar stories about Dr. Heber-Katz' research in other publications, such as the Science Daily and Nature."
Cancer is a very dynamic disease there is not, to the best of my knowledge, any way to just "turn off" cancer cells. The normal lifecycle of groups of cells consists of individual cells that "know" when to divide and when to die (aptoptosis), with cancer, cells may proliferate too rapidly, or cells, normal in all other respects, may simply not know when to apoptose. So there are many different facets of each individual cancer, and each patient with said cancer. For example: while some cancers may respond (by apoptosing) to genetic damage inflicted by cytotoxic chemotherapeutic agents, other cells may benefit from the mutation caused by said damage. Differnet cancers (and differnt populations of cancer cells in the same patient) may be driven by completely different mechanisms, especially as individual tumors evolve and adapt within their host, so again you'd be hard pressed to exact something from stem-cells that would/could just "turn it off."
the term "Cancer" is actually a pretty generic term used to describe hundreds of distinct diseases, much as "Infection" doesn't really tell you the nature of each individual infection (bacterial, viral, fungal, protazoal, parasitic, etc, etc - what kind of bacterial? G-, G+, acid-fast, hemolytic, coagulase +/-, toxin-producing, etc etc.). So when you say "cure cancer" or "turn off cancer" it's like saying "curing infection."
the only major difference I can see is a lack of control in cancer
this, again, is an over-simplification. it's much like saying the only difference i see with infectious disease and commensulistic/symbiotic bacterial colonization (such as your intestinal floura, which can cause infection if cirumstances are such) is that with infection your immune system can't keep them in check and they're in the wrong place, and with colonization this is not the case... or in more Geek terms: "the only difference i see between a PDA and an ULTRA-SPARC machine is that the ULTRA-SPARC box is faster"-it's just a lot more complicated than that...
Does anyone know how much research is going into a link between stem cells and cancer cells?
Contrary (i think) to what you were asking by this question, there is a school of thought that ties the two together. There was a paper published a short while ago which hypothesised that aging is the result of cancer suppression, and the two are almost inseparable. In other words the body's loss of regenarative ability is due to its control of accumulating genetic defects of stem-cells... i had just skimmed the publication and am not sure about its validity, but an interesting idea nonetheless... draw whatever conclusions from this as you like, but as i said i'm not positive of the validity of this report...
hmmm... that should be enough out of me :)
-tid242
With a few exceptions, secrecy is deeply incompatible with democracy and with science. --Carl Sagan
i find this a really interesting idea. Especially given that most cancers are not seen until after people are at an age where they generally have children (you've passed your genes on before you die of cancer). If you were to look at our pre-historic counterparts: if their life-expectancy were 20 years old and they had most of their offspring starting at 10-12 (these numbers are mostly guesswork on my part) then i would tend to think that evolutionally being able to regrow lost arms and legs would outweigh the ability to ward off cancer that doesn't strike until they're 25...
This is much the same as the differences between the rates of Progeria and Huntington's disease in people (people with Progeria don't have kids, but people with Huntington's do as the onset isn't until their 40's) even though, they're (apparently) similiar genetic abnormalities (ie in population genetics not taking into accout inheritence, their incidences should be equal)...
But getting back to regen/cancer: Of course there would be a fine balance between the two and figuring this out would involve lots of statistics and things my noggen doesn't compute so well, but i do find it interesting that there's so little regeneration in people.
conversely to my first point, since most regeneration would have probably been selected for, to take place before child-bearing age, and as we've advanced culturally and civically (child-bearing age) has markedly increased, and it's doubtful that missing a leg destroys your chances of having offspring if you live with a family in a cottage as opposed to running through savannas away from man-eating beasts and the like, maybe all this makes sense... (did you understand my convoluded run-on sentence?).
-tid242
With a few exceptions, secrecy is deeply incompatible with democracy and with science. --Carl Sagan
There is no real link there.
Stem cells are cells which have arisen following gametogenesis. Cancer cells, in at least 80% of cases, are cells that have started production of telomerase independently. Stem cells do not have telomerase, which is normall present only during gametogenesis, and in cancers.
A good company web site to look at to see how these things relate to each other, specifically dealing with oncology (the study of cancer) and limb regeneration, amon other topics, is:
http://www.geron.com/
The specific fram page with a discussion of their cancer research is:
http://www.geron.com/03.01_oncology.html
Intentional telomerase activation is generally only useful in wound healing therapies; this is because the cells in which the telomerase would act in this case have already specialized.
It's not know whether or not telomerase could act on stem cells directly, permitting "farming" of stem cells (an interesting idea, raised by your question). My gut feeling on this would be "no", based on the existance of teratomas, but I'm willing to be wrong (particularly if it ends up making me immortal... 8-)). The regenerative medicine page is at:
http://www.geron.com/03.03_regenmed.html
Note that Geron (the company whose site this is) has the patent on the genes coding for human Telomerase, owns the patents that led to "Dolly the sheep", and is interesting for other reasons.
The company was originally founded -- and their web page used to claim this -- to find a cure for human aging. They have a more mainstream message, these days, but they are certianly making progress on their original goal, even if they are getting a lot of products out of the intermediate work.
-- Terry