
Scientists create a working animal limb in a lab - mhb
http://bioengineer.org/bioengineering-breakthrough-scientists-create-a-working-animal-limb-in-a-lab/
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gricardo99
if this method can "scale-up" to any arbitrarily complex tissue, then
conceivably could you decellularize and re-implant an entire donor body, and
do a head transplant? Effectively, giving someone a brand-new body?

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elijahz
For now it seems you would need a donor body to act as the "scaffolding" for
your progenitor cells. Pessimistically, there may one day be a blackmarket for
scaffolding cadavers with desirable features.

> While the progenitor cells needed to regenerate all of the tissues that make
> up a limb could be provided by the potential recipient, what has been
> missing is the matrix or scaffold on which cells could grow into the
> appropriate tissues.

> ... living cells are stripped from a donor organ with a detergent solution
> and the remaining matrix is then repopulated with progenitor cells
> appropriate to the specific organ.

I wonder if a person could also "upgrade" their body, or invent articulate
organs with unique functions, such as printing a scaffolding for wings or a
specialized muscle structure attached to the hip for opening beer bottles.

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netcan
Perhaps they can strip back your own body to a scaffolding and regenerate the
tissue. You spend a week as a brain-in-a-vat while your body gets regenerated
then you start again.

Sci Fi gold.

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fho
And by far not an uncommon trope.

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techwraith
Does this mean that we'll get lab grown bone-in leg of lamb soon?

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logfromblammo
First, you start with a naturally grown bone-in leg of lamb. Then you
completely decellularize it by running a detergent solution through it for a
week. Then you culture the replacement lamb cells, and inject them into the
appropriate places on the limb. Then you place the leg in a bioreactor and
wait until the cell cultures spread throughout the existing matrix. Then, when
you finish, you have a lab-grown leg that is 80% as good as the natural one!

Having to start with a natural limb seems to be the roadblock here.

So we're going to need to be able to volume-print an extracellular matrix
before anybody gets any vat steaks. I'd guess a destructive scan of a single
natural beef tenderloin and some stem cells from the World's Most Delicious
Bovine would allow for unlimited numbers of vat-grown copies. And then it
would still take quite a while to bring the unit cost down below feedlot
cattle.

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techwraith
So I guess I just have to wait until we have good enough 3D scanners to build
a model of the non-cellular structures in the leg, then we need good enough 3D
printers to print edible non-cellular structures at small enough sizes for the
re-cellularization to work, and _then_ I can eat a lab grown leg of lamb!

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robbiep
We basically just need a way to print 3D collagen. We largely know what the
structure is, the problem is replicating it.

This is compounded because collagen strength/structure increases after
deposition through the action of enzymes that crosslink collagen chains - a
problem that would need to be overcome in order to print it

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ChuckMcM
Wow it must be great to be a Rat :-) There must be a story where the humans
die off leaving behind a sentient rat species with a really deep medical
knowledge.

That said, this feels like a pretty big bump in the tissue engineering field.
I hope it holds up when they move up to larger mammals!

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reasonattlm
Doctor Rat.

But don't read it if easily made unhappy by literature.

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n0us
I wonder if there are any applications in building biological robots? I don't
know too much about the process so perhaps this is far fetched but if you
could build a robot with organic appendages that could be "swapped out" once
they are used or damaged I would image you could end up with something far
more versatile than the mechanical equivalent with servos/solenoids etc.

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mmusson
A nervous public will demand that organic robots be given an arbitrarily short
lifespan as a failsafe. Say four years. And those robots would also be
restricted to working in outer space because it would be too hard to control
robots indistinguishable from ordinary humans on Earth.

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david-given
Then it will start being four o'clock in the morning and raining. All. The.
Time.

On the plus side, there will be a sudden popularity in delicious noodle bars.

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rzzzt
Fancy umbrellas will also be abound.

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lisper
Hm, they claim that it has "functioning" muscle tissue. But in the video the
limb doesn't move, so I wonder in what sense the muscle tissue can be said to
be "functioning."

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polymathist
From the article: "Functional testing of the isolated limbs showed that
electrical stimulation of muscle fibers caused them to contract with a
strength 80 percent of what would be seen in newborn animals. "

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lisper
Ah. Thanks.

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sakopov
I don't follow. We're talking about body appendages from dead donors that have
been washed of any cellular material so they can be retrofitted with cells
from the recipient? I guess I'm not seeing what exactly is "lab-grown" here.

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fsloth
The limb? Animal donor cells do not spontaneously start to reconstruct the
tissue when removed from host. Otherwise we would be sprouting all over the
place.

Anyway, consider the washed out matrix just as a scaffolding for the proof of
concept. We can probably eventually print cartilage so then the scaffolding
can be done from first principles.

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netcan
Not sure what to make of this.

If you have a genetically compatible limb, how much of the way are you to
having a transplantable limb?

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dogma1138
They already can reconnect limbs and other body parts
[https://en.wikipedia.org/wiki/Replantation](https://en.wikipedia.org/wiki/Replantation).

The problem like always is reconnecting the nerves which isn't something you
have to worry about when transplanting organs.

If say you transplant a heart that heart will never talk to the recipients
brain it will always continue to function on it's own, this also means that
the brain cannot regulate the heart functions through the nervous system so
mental states do not affect the hearts operations as they would with most
people, hormonal neurotransmitters like adrenaline will still work tho.

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netcan
Fascinating.

Biology really is amazing technology. It's very exciting to see progress in
understanding, interacting with and augmenting it.

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davesque
Fascinating but extremely creepy.

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medell
Last year I had dinner with a student getting his PhD in Future Studies. I
asked what are the most interesting technologies we would see in our lifetimes
that the majority doesn't know about. He said, without hesitation, graphene
and growing human body parts.

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seibelj
What kind of job would you get with a PhD in "Future Studies"?

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Keyframe
And what does that program entail and where do you study that?

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medell
[http://www.futures.hawaii.edu/](http://www.futures.hawaii.edu/)

