Brain transplants

hammertime

We can currently do transplants of lungs, kidneys, livers, etc. if those organs are damaged or diseased. Will we ever be able to do so with brains?

I've heard a lot about the possibility of growing replacement organs in vitro or using 3-D printers to create replacement organs. When will we be able to do so with brains? What obstacles lie in the way?

Evo

This has been asked here so many times.

You can find "brain transplant", whole body transplant", "head transplant", etc...

A recent one.

http://www.physicsforums.com/showthread.php?t=518536

I've decided to leave this open so people can go into more details of why it's not possible right now. ryan_m_b is our expert on growing body parts.

Pythagorean

There has been "successful" head transplants of monkeys.

White states that it is "impossible to reconnect nerve threads once they've been broken" (the monkey doesn't gain control of the new monkey's body, just it's support systems). Nor does the monkey live very long after the surgery.


brace yourself:

Evo

I don't consider that successful, it's like the reattached dog heads, those didn't work either.

Pythagorean

Yeah, me either. But White considered it successful as far as his goal was concerned. Baby steps I guess. Definitely a required part of a true transplant: getting support systems tied in on the new rig.

But yeah, hooking up the nerves is the important part.

Ryan_m_b

Can I have that as a title?
The problem with a brain transplant is twofold; firstly the brain is reliant on millions of connections to the spine and each of these connections is measured at a cellular level. Because of this it is pretty much impossible to envision how these connections can be severed, the brain held in a stable condition and then reconnected in another body. Secondly the brain is the seat of the mind and therefore any change to it (i.e. replacing chunks) will damage the personality inside even if you could regenerate the connections perfectly.
This is the field of regenerative medicine. Already there are regenerative medicine products on the market for things like skin (e.g. matriderm and dermagraft) and very recently a number of successes in the generation of tracheas and windpipes. There are avenues of research towards 3D printing of cells but these are very primitive. The main focus of the field for both in vitro and in situ is the development of tissue scaffolds whose characteristics (size, mechanical forces, topology, hydrophobicity, conductivity, porosity,surface chemistry, attached biomolecules etc) can both mimic the natural properties of the extracellular matrix/cell niche in question and control cell behaviour in desirable ways. The ideal scaffold would be one that could be placed in a patient, attract stem cells from the body, induce their differentiation whilst coordinating millions of cells at once to regenerate multiple tissue types and finally dissolve (or technically dissolve as it goes).

The biggest obstacles to these is understanding the various ways in which cells respond to environmental stimuli. Cells are highly sensitive entities; slight changes in pressure, pH, mechanical stimulus, chemical concentrations etc can have huge effects. So at the moment a lot of regenerative medicine research focuses on discovering what effects different conditions have for example: certain neurons extend their axons in parallel to deep groves and perpendicular to shallow ones. This lack of knowledge and lack of sophisticated technology mean that regenerative medicine products are limited to simple tissues rather than whole organs.

Other obstacles include the difficulty in creating a scaffold that can coordinate multiple cell types via mechanisms that don't interfere (or complement) with the other types of cells and angiogenesis. The latter is a big problem because as it stands in vitro tissues are limited in size because they have no vasculature and so must rely on oxygen diffusion for respiration.

hammertime

Couldn't nanotechnology (not necessarily molecular assemblers) or stem cells help with disconnecting and then reconnecting the brain to the spinal cord?

Other than that, is the only obstacle to curing things like brain cancer and cerebral palsy with brain transplants a mere lack of know-how?

DaveC426913

I am not weak of stomach, but the video of those dogs kept alive while decapitated haunts me.

These stills of the monkeys are rehashing that.

And right before bed...

Ryan_m_b

Hammertime, what do you mean when you say "nanotechnology"? Judging by previous threads you seem to have a very narrow and Science-Fiction orientated understanding. Nanotechnology is a normal part of regenerative medicine, all the treatments I outlined above are generated with nanoengineering principles. To reconnect the brain would require a tissue scaffold of huge complexity. This is not a trivial thing, current research on nerve conduit scaffolds focuses on large nerve fibres. Making billions of synaptic connections in just the right way is a world apart from this. Also stem cells are not a panacea. They have their place in tissue engineering and there are times when they are inappropriate, for example: it may be beneficial to seed the scaffold with stem cells first and induce their differentiation but it also may be better to seed the scaffold with primary cells instead.
Replacing large chunks or even an entire brain is not the same as replacing other organs because the brain is the seat of consciousness. If I cut out your brain and put a new one in (let's assuming this could be done perfectly) the patient who wakes up would be a baby, i.e. a new person. Having said that small scale regeneration of specific structures would be useful, just try to think it through when you propose whole or large portion brain transplants in terms of the resident mind.

hammertime

Why would the patient who wakes up be a baby? If the brain put into him is identical to his old brain (has all the same memories and personality), wouldn't it be the same as going to sleep and waking up, albeit with a huge bandage on your head?

Also, what about artificial brains made of, say, silicon? We have artificial hearts? Could we one day transplant artificial brains (i.e. non-biological brains) into patients with brain tumors? Has IBM already helped us get closer to that (http://www.bbc.co.uk/news/technology-14574747)?

Ryan_m_b

This is getting silly. How exactly are you going to make an entire brain which is exactly the same on a cellular level? This is science fiction. There is no technology that would allow you to determine the position and characteristics of every cell in the brain and no way to build a scaffold that would induce the formation of an identical brain.

We do not have artificial hearts. We have prosthetic pumping devices that can replicate some of the function of a heart for a limited amount of time, do not confuse this with the idea that we can make something as good as a heart. There is no technology (be it silicon or magic dust) that we can use to replicate the brain let alone transplant it in, this is just pure fantasy. IBM has designed chips that work in a similar fashion to neurons. This is about as close to a brain as a drawing of a leaf is to a forest.

Evo

The Op has been answered.