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."

Comments

A good read.

[Anonymous Coward]

The Body Electric by Robert O. Becker, MD.

This book describes the efforts of Becker to try to study human limb regeneration and how he was shot down at every opportunity by the establishment. A fine example of how university educated people turn into religious-style bigots.

I didn't RTFA, but I'm sure it's a typical example of how Becker ridkes his career to bring to light new evidence, but 20 years later someone else takes the credit.

Re:Cancer link?

[tid242]

If we can find a way to turn on stem cells, maybe the same switch could work to turn off cancer?

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

evolution?

[tid242]

Scientists wonder why the ability to regenerate has not spread more widely through evolution...

...the advanced immune systems of higher life forms may mistake rapidly proliferating cells for cancer and kill them.

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

Re:evolution?

[tid242]

I've know 2 kids that died of cancer. One of 'em had reached puberty, the other had not.

I'm trying to to loose my cool because this being an emotional issue for me, I take offense at what you said.

i am a bit taken aback by this, what i said was by no means to insinuate that children do not develop cancer, nor surely to offend anyone. i think the key words here are "most cancers" this does not mean the same thing as all cancers. point of fact (US 2000 cancer stastics):

incidence:
male: Prostate (30% of all cancers), Lung (14%), Colon/rectum (11%), Bladder, Melanoma (5%), etc, etc, leukemia (3%),

female: Breast, Lung, Colon, Uterine, etc. etc. (leukemia isn't even listed as one of the most common female cancers)

cancer deaths:
male: Lung(31%), Prostate (11%), Colon(10%), all others equal to or less than 5% (leukemia = 4%)

female: Lung (25%), Breast(15%), Colon(11%), pancreaus (6%), all others less than 5% (leukemia = 4%)

these stastics exclude non-melanoma skin cancers

of cancers Leukemias (especially fast-growing leukemias such as ALL, which are amongst the most easily treated of all cancers, if this be any comfort for you) account for 30% of all childhood cancers (and i think neoplasms represent usually w/i the top 5 childhood killers, while the nation's non-age-adjusted 2nd largest killer only behind heart disease), leukemia is 10 times more common in adults than it is in children...

all and all survival rates are higher in children than they are in adults, many times because of cancers specific to children, but also lending to a better chemotherapeutic/radiation tolerance in children allowing health-care providers to "push the dose..."

while cancer does certainly present in children, the fact remains that children constitute a much smaller cancer population, (even when statistically adjusted for population-size).

as i said before, it was not my intent to offend anyone, but the fact remains that general population trends show that cancer incidence increases with age (possible curtailing of the curve could be accounted for by genetic predispositions of cancer). Also, reember that personal experience is not necessarily indicitive of population trends. And likewise population trends does not necessarily reflect cancer incidence in your particular state, country, neighborhood, family, circle of friends, etc. So my original comment was not direct toward people you know, but toward the greater human condition. i am also painfully aware of the differences between statistics and the effect illnesses have had on my life and my family.

my source (american cancer society).

-tid242

There is no real link...

[tlambert]

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