people regrowing limbs?


MongoTheGeek

macrumors 68040
I don't see why it isn't being done already. They can regrow bones and muscles and skin. (Muscle and skin can be grown from other muscle and skin stem cells (adult from the patient. Autologos so no chance of rejection like with embryonic stem cells)) Bone requires the a disintegrating matrix in the correct shape.

Nerves not so much but that might be just coaxing existing neurons to extend. Gene therapy might be a way to go in the future but right now we can do it.
 

jréh

macrumors newbie
Sep 22, 2006
9
0
melbourne, australia
it sounds a terrible thought now but this is a great argument for farming human clones to be used for body parts, which (go figure) are less likely to be rejected by the recipiant.
 

thedude110

macrumors 68020
Jun 13, 2005
2,479
2
jréh said:
it sounds a terrible thought now but this is a great argument for farming human clones to be used for body parts, which (go figure) are less likely to be rejected by the recipiant.
Very well said.

The consequences of something like this (intended and unintended) freak me out more than a little. I'm all for getting limbs onto the limbless, but in a thoroughly tested, highly regulated way ...
 

McT

macrumors newbie
Sep 7, 2006
19
0
I believe with the Stem-Cell "cloning", individual body parts and develop-able, gene protiens can be created WITHOUT creating a grotesque, sci-fi test tube clone of yourself.

I would have problems actually having to clone an entire "me" to be dissected and harvested. I like my chicken boneless, and my clones ala carté :D
 

topicolo

macrumors 68000
Jun 4, 2002
1,672
0
Ottawa, ON
MongoTheGeek said:
I don't see why it isn't being done already. They can regrow bones and muscles and skin. (Muscle and skin can be grown from other muscle and skin stem cells (adult from the patient. Autologos so no chance of rejection like with embryonic stem cells)) Bone requires the a disintegrating matrix in the correct shape.

Nerves not so much but that might be just coaxing existing neurons to extend. Gene therapy might be a way to go in the future but right now we can do it.
You're simplifying this far too much. Skin and muscle cells grown in the lab are extremely thin and can thus be vascularized (have your body extend its blood vessels into them) relatively easily. Growing tissue and shaping them into limbs is another matter. There are hundreds of individual musculoskeletal systems in a normal human arm plus thousands of vascular branches to feed those muscles. In addition, each of those muscle groups need different types of nervous connections, depending on whether they're a part of the somatic, sympathetic autonomous or parasympathetic autonomous nervous system. Add that to the intricate bone and tendon structures of the hand, and your picture becomes less easy to accomplish. Current technology doesn't have the necessary advancements to do something that complicated without using stem cells, unless your definition of a limb is a bag made of lab-grown skin and stuffed with lab grown muscles.
 

MACDRIVE

macrumors 68000
Feb 17, 2006
1,695
3
Clovis, California
So going according to the thread topic:

If I had a hand that didn't work good, I would be better off removing it and letting a new one grow, as opposed to trying to repair the existing one correct?
 

MongoTheGeek

macrumors 68040
topicolo said:
You're simplifying this far too much. Skin and muscle cells grown in the lab are extremely thin and can thus be vascularized (have your body extend its blood vessels into them) relatively easily. Growing tissue and shaping them into limbs is another matter. There are hundreds of individual musculoskeletal systems in a normal human arm plus thousands of vascular branches to feed those muscles. In addition, each of those muscle groups need different types of nervous connections, depending on whether they're a part of the somatic, sympathetic autonomous or parasympathetic autonomous nervous system. Add that to the intricate bone and tendon structures of the hand, and your picture becomes less easy to accomplish. Current technology doesn't have the necessary advancements to do something that complicated without using stem cells, unless your definition of a limb is a bag made of lab-grown skin and stuffed with lab grown muscles.
I realize that the limb generated by the means that i described would for the most part be useless. You wouldn't be able to build up enough muscle mass in vitro and the tendons etc. would be almost useless. A few years of therapy and I think it could be made into something useful.

I don't think its a lack of technique. I think its a lack of craftmanship and practice as well as it being far cheaper to transplant someone elses.
 

topicolo

macrumors 68000
Jun 4, 2002
1,672
0
Ottawa, ON
The problem is that no amount of therapy can make that arm sausage grow all the cell types neccessary to get a working arm. How do you create the basement membrane that separates different tissues? What about preventing connective tissue from invading everything? how are you going to be able to maintain the repair and regeneration of old or injured tissues (non stem cell can have a life of as little as 2 weeks and muscle cells don't divide period--they increase in size). If you're using stem cells, how are you going to harvest the massive quantities you need and stimulate them to grow? Even if we figure those out, there has been recent evidence that seems to indicate that a lot of cancers really come from mutated stem cells. How are we going to ensure that all the stem cells we're using to grow the arm don't malfunction and turn into tumors? We still don't know enough about stem cells to fully control all their differentiation and migration pathways to even try making one of these things. So far, this is still the realm of science fiction. Maybe in about 30 years we'll be able to make something like this properly.

In the meantime, I would expect simpler body parts to be manufactured first. Cosmetic stuff like real human ears, noses, internal smooth muscles, etc.
 

mufflon

macrumors 6502
Sep 15, 2006
264
2
MongoTheGeek said:
5 or 10 years ago I saw a human ear grown on the back of a mouse. Very freaky.
But that's just cosmethics - an ear is pretty basic - you can even hear quite decent without one! (not without the parts inside of the head ofc), whereas an arm or leg is a lot more advanced and can't be constructed with our current state of technology.
 

MongoTheGeek

macrumors 68040
mufflon said:
But that's just cosmethics - an ear is pretty basic - you can even hear quite decent without one! (not without the parts inside of the head ofc), whereas an arm or leg is a lot more advanced and can't be constructed with our current state of technology.
Yes. I pointed it out by way of agreement. Ear is skin and cartilage. Ears and noses are probably only waiting on FDA approval.
 

Don't panic

macrumors 603
Jan 30, 2004
5,551
695
having a drink at Milliways
MACDRIVE said:
So going according to the thread topic:

If I had a hand that didn't work good, I would be better off removing it and letting a new one grow, as opposed to trying to repair the existing one correct?
quite possible, if they "unlock" the secret of the MRL mouse. I think it would be possible that it would come with a higher susceptibility to cancer, but one would have to weigh the trade-off.

And this approach would have nothing to do with growing clones, or limbs, in vitro. it would consist in inducing one's own body to regenerate the missing part.
it is common in many anymals including the MRL mice, so in princible should become possible in humans too.
 

Dros

macrumors 6502
Jun 25, 2003
484
1
Although the limb is complicated, there is a lot of self-assembly programs that just need a kick start to get going. For example, a bead soaked in a single growth factor, when implanted into the side of a chick, is sufficient for an extra entire, well-patterned limb to grow at the site of implantation. So cells know what to do when given the right signal, it is just a matter of controlling that signal properly. So it may not require nanomachine assembly, just a bead with a signal on it, and a way to get the cells to respond.