Regeneration of skin and limbs

[Stereolab]

Does every animal have some sort of natural, physical "healing" capability? If so, is there reason to believe that this is a capability that evolves?

If I get a paper cut on my leg, it will heal itself and be good as new. If I get a bad cut on my leg, it will heal itself, but maybe leave a scar. If someone chops my leg off, it's not going to grow back.

Is there any reason to believe that, if the human race were to last thousands or millions more years, we would "evolve" to the point where we could grow complete limbs and stuff back, naturally? Or do we get along well enough as we are now, therefore this wouldn't happen?

[Stereolab]

I apologize, I meant to put this in the Science section. It would be cool if someone could move this thread. Sorry, I'm new.

[geni]

Babies can grow back fingers. There was even a case where this happened to a seven year old. It is generaly thought that there is some disadvantage (maybe cancer maybe the amount of energy involed) in mentaining the abilitly to regrow limbs and digits latter in life.

[Iamme]

....but scientists believe that all of this, and more...is doable. And they are working on this very thing. I think there is in article about this in my last Discover magazine. I haven't gotten around to reading too much of it yet. They KNOW it's doable because so many animals/sea creatures can do this very thing.

[Yahweh]

If we can regenerate heads, that would be nice...

[DVFinn]

The day is very likely coming when we will be able to regrow severed limbs and even organs. The biggest blockade to these technologies is political. The ridiculous limitations imposed on stem cell research and the media supported misconceptions about cloning research will unfortunately delay these advances, at least in the US.

[Nasarius]

Originally posted by DVFinn
The day is very likely coming when we will be able to regrow severed limbs and even organs.

Actually, regrowing organ tissue is significantly easier than growing limbs. IIRC, you can even grow liver tissue without stem cells. I don't know how you'd regrow something so complex and perfectly shaped like a limb. I'd say it probably won't happen for decades at the least.

[uneasy]

This reminded me of a presentation I saw in school years ago about static electricity. After explaining going over static electricity generators and anecdotes, the guest lecturer showed photos of missing limbs of newts that had static electricity applied to them, causing their limbs to regrow.

Now I'm thinking it was all bogus, mainly because I've never heard anything about it since, and regrowing limbs seems like something people would hear about.

Has anyone heard of this static electricity / regrow limb thing? I searched on it and only found pages of magic spells for role playing games.

[SteveGrenard]

Frogs and salamanders (amphibians) can grow back missing digits and even limbs but they are not as good as or the same as the original.

For research into the use of low levels of electric stimulation to promote healing of wounds as well as limb/digit regeeration experiments in amphibians and lower life forms, check out the works of

Robert O. Becker M.D.

He also wrote a few books on this, one I remember called The Body Electric with Gary Selden.

Many orthopedic departments now use electrodermal stimulation techniques to promote healing, including even of small fractures. This is not an area I am totally familiar with but you could also check MedLine on these techniques.

[uneasy]

Originally posted by SteveGrenard
Frogs and salamanders (amphibians) can grow back missing digits and even limbs but they are not as good as or the same as the original.
Yeah, that's what I thought. It's one of those memories of something I would think much differently of if I saw it now. My college brought this guy in to lecture. At the time I thought, "That's interesting" and now that I look back I just think, "How dare they feed me such bull, and who was that guy?"

[Mercutio]

They lopped off my thumb at birth--still gone.


If regeneration happens at a particular rate within a population (open question), shouldn't we see a particular percentage of regrown foreskins in circumcised males?


Any "we may evolve X" requires a selective advantage to X. As long as we have the level of medical care we currently do, I see not a whole lot of selective advantage to being able to regrow a limb (especially if someone who does not have this ability can still have it surgically reattached).

[bug_girl]

I have Never heard of any infant humans, or any mammals for that part, regenerating anything.
Current biological theory has it that the ability to regenerate was lost long ago. I think that the ability to *spontaneously* regenerate will never evolve in humans, or other mammals.

In humans, especially, there is no selective advantage to someone with this ability in terms of increased reproductive capacity (unless you are john bobbit:) )
i mean, i can imagine the party:
"hey look, i regrew my finger! wanna have my kids?"

There is plenty of potential for genetic modification to allow growth, but i think that is a long way away, since everyone seems convinced that biotech is a slippery slope. (and in some cases, it is.)

The genome of mammals is too intertwined for something like this to spontaneously occur without something very nasty probably also going wrong. Cancer is spontaneous, uncontrolled cell growth. not a good thing.

[SteveGrenard]

Originally posted by Mercutio
They lopped off my thumb at birth--still gone.


If regeneration happens at a particular rate within a population (open question), shouldn't we see a particular percentage of regrown foreskins in circumcised males?


Any "we may evolve X" requires a selective advantage to X. As long as we have the level of medical care we currently do, I see not a whole lot of selective advantage to being able to regrow a limb (especially if someone who does not have this ability can still have it surgically reattached).

Sorry, spontaneous regeneration of limb buds and digits only occurs in frogs and salamanders, and not in mammals or birds or lizards and turtles for that matter. Snakes and lizards whose tails have been chopped/bitten off or were spontaneously twisted off, a thing called caudal autotomy or self-severing, do regenerate those but they are shorter and stubbier than they were before.

Er, frogs and salamanders don't have foreskins so that issue is moot for them.

[plindboe]

Originally posted by geni
Babies can grow back fingers. There was even a case where this happened to a seven year old. It is generaly thought that there is some disadvantage (maybe cancer maybe the amount of energy involed) in mentaining the abilitly to regrow limbs and digits latter in life.

:eek:

Are you sure this has really happened? Quite interesting if true. Have you anything that can back it up?

[SteveGrenard]

I could find nothing on MedLine to support this assertion. There were, however, two abstracts of interest involving (induced, not spontaneous) mammalian regeneration of amputated fingers/toes. There is also considerable research indicating that retinoids could favorably affect such regenerative abilities. Becker, whom I cited earlier, researched the use of electrical stimulation to foster this.


Anat Embryol (Berl). 1987;177(1):29-36.


Open finger tip healing and replacement after distal amputation in rhesus monkey with comparison to limb regeneration in lower vertebrates.

Singer M, Weckesser EC, Geraudie J, Maier CE, Singer J.

Department of Developmental Genetics and Anatomy, School of Medicine, Case Western Reserve University, Cleveland, OH 44106.

The left thumbs and great toes of three 8 1/2 month old Rhesus monkeys (Macaca mulatta) were amputated in guillotine fashion one millimeter distal to the base of the nail and allowed to heal by the conservative open wound method. Healing occurred in seven to ten days in these small digits. Each of the thumbs and toes grew back with some blunting and shortening of the digit tips, but were functional. The new structures were cosmetically pleasing as in the human instances. The nails grew essentially to normal size and shape supported by the remaining portions of the distal phalanges. Histological studies showed no evidence of blastema formation such as is observed in the regenerating limb of the Urodele (newt) taken as the comparative representative. The possibility of improving the regrowth is discussed against the background of our knowledge of the importance of nerve during limb regeneration in lower vertebrates.



Anat Rec. 1985 Feb;211(2):156-65.


Bone healing after amputation of mouse digits and newt limbs: implications for induced regeneration in mammals.

Neufeld DA.

Postamputational healing was compared in nonregenerating and regenerating animals to determine whether bone healing might interfere with a regenerative response in mice. More than 150 mouse toes and 100 newt limbs were examined at the light microscope level. Stages of normal bone healing with approximate times of occurrence were established. Major differences in healing of these two species were seen. The periosteum produced hyaline cartilage, woven bone, and chondroid bone in mice, but only hyaline cartilage in newts. The endosteum produced woven bone in mice but no new growth in newts. Dead bone persisted in mice but was removed in newts. The marrow cavity became sealed in mice but remained open in newts. Despite these differences both animals produced skeletal tissue distal to the amputation plane. Woven bone formed distal to the amputation plane of mice. Cartilage formed distal to the amputation plane of newts, but cartilage was never seen distal to the plane of mice. Results of previous studies reveal that cartilage can be formed distal to the amputation plane of experimentally treated mice. Thus, although it does not regenerate, mouse bone is capable of producing, distal to the amputation plane, the type of skeletal tissue which appears at that location during an epimorphic regenerative response. This observation, in combination with other experimental results, indicates that both skeletal and soft tissues at the amputation site of treated mammals can resemble comparable tissues of newt limbs at an early stage of regeneration.