Body replaces itself, but not individual limbs

[Loren Booda]

How is it that, although the human body mostly regenerates itself every dozen or so years, it cannot replace more than a very simple severed part?

http://en.wikipedia.org/wiki/Regeneration_(biology)"

 

[Blenton]

Because whoever designed the human body did a horrible job and should've been axed long ago.

Anyway I think the main reason is not that it can't but why it can't, and if I'm not mistaken it was evolutionary. Most animals would probably not survive after losing a limb, so why invest so much energy in regrowing it? Too bad we haven't found the 'switch' to turn it back on.

 

[Andy Resnick]

The human body replaces itself much faster than 'every dozen or so years'- the intestinal epithelium is replaced every few days.

In any case, the ability to regenerate is driven by stem cells- and we (terminally differentiated human beings) no longer have the stem cells able to regrow entire limbs (or organs).

 

[LennoxLewis]

It's not that we can't, it's simply that our body doesn't want to. Basically... if you have a computer, you can't create Word files without MS Office. As soon as we know how to install MS Office (i.e. modify cells and use stem cells), regeneration should be possible. It's a complicated process though, with high risk of cancer induction.

The human body replaces itself much faster than 'every dozen or so years'- the intestinal epithelium is replaced every few days.

In any case, the ability to regenerate is driven by stem cells- and we (terminally differentiated human beings) no longer have the stem cells able to regrow entire limbs (or organs).

I actually read an interesting article regarding this subject recently. Since 2007, we're able to give cells an innocent virus that turns a fully developed cell back into a stem cell; since last year this is also possible for human cells. However, there are still a lot of complications in the way and it will be at least 10 years before this technology because viable.

 

[Monique]

we (terminally differentiated human beings) no longer have the stem cells able to regrow entire limbs (or organs).

Or we don't have the niche that sends the correct signals to activate the stem cells to start organizing themselves in a new limb.

 

[Ruslan_Sharipov]

Please, is there anybody here who REALLY WANTS to start an experiment in HUMAN LIMBS REGROWING? Not just posting messages, but to act in practice?

 

[mack_10]

Axolotls can regenerate limbs so the mechanism has evolved at least once.

Interesting work been done with enzyme extracted from pig bladders - can regrow distal digit, chop of the last bone in your thumb, coat it with this enzyme and the thumb regenerates, nail and all.

development is a phased system with the messengers for limb generation appearing at the appropriate time in utero, if you could paint the right messengers on the stump of a limb it should regenerate, worth looking into

 

[Lievo]

How is it that, although the human body mostly regenerates itself every dozen or so years, it cannot replace more than a very simple severed part?

As mack said, axolotls show that there is no physical impossibility. So the character may have been lost through neutral mutation (neutral because when one lose a limb, most of the time survival is unlikely).

 

[madcat8000]

I think monique is quite right in that its an information problem and not a physical one. I've long held the belief that it would be easier to regrow an entire body than to replace a finger. But who knows, maybe someday someone will find the "regeneration button".

 

[Loren Booda]

I think monique is quite right in that its an information problem and not a physical one. I've long held the belief that it would be easier to regrow an entire body than to replace a finger. But who knows, maybe someday someone will find the "regeneration button".

Information, like a hologram?

 

[Lievo]

Information, like a secret key turning some cells to start a new limb.

 

[Borek]

We discussed the problem in more details here:

https://www.physicsforums.com/showthread.php?t=425107