The Speculist writes that:
Posted by DeLong at May 3, 2004 06:53 PM | TrackBack | | Other weblogs commenting on this postThe Speculist: Cellular Competence: ...scientists from King's College, London announced success in getting mice to grow new permanent teeth from stem cell packets injected into the gums. The procedure is fairly simple. Doctors take stem cells from the patient. These are unique in their ability to form any of the tissues that make up the body. By carefully nurturing the stem cells in a laboratory, scientists can nudge the cells down a path that will make them grow into a tooth. After a couple of weeks, the ball of cells, known as a bud, is ready to be implanted. Tests reveal what type of tooth - for example, a molar or an incisor - the bud will form. The scientists involved see no reason why this technology can't be adapted for humans.
Both of these stories beg the question "how does the stem cell know how to incorporate itself into the body?" In both of these cases the stem cells are coaxed by scientists into becoming brain cells or tooth cells, but such cells would be useless on their own. Brain cells have to interact with other brain cells. Tooth cells need to work with other tooth cells and the surrounding tissue in order to form a healthy tooth. How is this accomplished? William Atkinson touched on the answer in the last chapter of his book, "Nanocosm."...
[T]op down control is not practical (you can't micromanage the work of millions of molecular assemblers) or even possible. Certainly, nature doesn't attempt to micromanage the work of cells. Our brains are not in control of cellular activity within our body. The cells have to be autonomous workers – cellular automata that know their place within the overall scheme of things. Atkinson suggests that in this respect our molecular assemblers must emulate life. Consider the nautilus. This beautiful structure was self-assembled at the molecular level. How? The mathematical description of this structure is incredibly complex. Do the cells understand the complex mathematics involved? No. Then how was it done?
The nautilus develops from the innermost chamber out. According to Atkinson the cells that build these chambers follow a simple program not unlike the following: If prior chamber = nonexistent, then build chamber size A. If prior chamber = existent, then build chamber size 110% of prior chamber size.
These two lines of code give every nautilus cell much of the information needed to perform a very complex task.
A new kind of ego ummm... science has a chapter on cellullar automata applied to biology - it has some pretty pictures and is worth a look if you don't mind lots of speculation.
Posted by: rps on May 3, 2004 07:35 PMI meant to include this as a link:
http://www.wolframscience.com/nksonline/section-8.6
I guess movable type eats hyperlinks now?
Nothing like "local control". And you thought the queen ant "told" her workers what to do?
http://www.stigmergicsystems.com/stig_v1/stigrefs/article3.html?964301
Posted by: bakho on May 3, 2004 07:57 PMThe same way that cancer represents something gone haywire with the cells ability to chemically communicate with those surrounding it, sounds like...
Posted by: ligimos on May 3, 2004 08:59 PMYou state: "Both of these stories beg the question "how does the stem cell know how to incorporate itself into the body?" "
To "beg a question" does not mean, "to state a question that requires raising." Rather, this:
"An argument that improperly assumes as true the very point the speaker is trying to argue for is said in formal logic to “beg the question.” Here is an example of a question-begging argument: “This painting is trash because it is obviously worthless.”
See, "Common Errors in English," at: http://www.wsu.edu:8080/~brians/errors/errors.html#errors
Posted by: Zachary Tumin on May 4, 2004 02:40 AMthe way things go in english," Begs the question", will come to mean "Poses the question".
Posted by: big al on May 4, 2004 03:43 AMBoth of these stories beg the question "how does the stem cell know how to incorporate itself into the body?"
There's a fairly simple answer to that...CHEMISTRY. If you precisely replicate the local environment present when the tooth originally formed, the stem cell bud should do its job again and form new teeth.
Posted by: --locus on May 4, 2004 06:27 AMI was going to protest the misusage of "beg the question"; but at least I was aware that DeLong didn't write it.
Brad, the frequency at which commenters confuse what you quote with what you write might ought to make you rethink how heftily you quote other sources. I admit that I find some of this stuff that you post interesting, but you really shouldn't be (merely) a blog/news aggregator. And I've never been comfortable with the way you quote *entire* articles, which is certainly not fair use.
Just my two cents.
Posted by: Keith M Ellis on May 4, 2004 06:27 AMFunny, as someone usually very interested in cellular automata (see URL) I thought the take-away was: Wow, I could grow a mouthful of new perfect teeth some day very soon--and stop wondering if I ought to get those old amalgam fillings replaced before I go as mad as a neocon and start fantasizing about world conquest.
I was thinking about the way fluoride supposedly works by replacing the hydroxyl group as teeth form. I wonder... Once you figure out how to grow live adult teeth in the lab, could you grow them in a controlled environment and get even tougher enamel than fluoride provides (maybe using something that would not be safe to provide as an oral supplement). I'm not sure how implanting fully developed teeth would compare to growing them in place.
One other thing is that I assume none of this is worth much unless your gums are healthy.
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