How close are we to 3D printing the human heart? | Hacker News Reader

How close are we to 3D printing the human heart?

humanbioscience.org

54 pointsbenzine39 comments

What I don't understand is why we don't use existing biology as a tool. Why do we have to go out of the way to create an exogenous heart? That's like programming with magnetized needles. The human body is the perfect compiler for growing human hearts (and other organs), yet we want to throw away millions of years of evolution and try to roll our own.

I think you'd find much broader application if you cloned humans and neutered the genes for cephalization. It's a little macabre, but think about it: you'd have host bodies ready for organ harvesting and for medical or systems-level biology research. You can even tweak them for whatever experimental (or donor immunocompatibility) parameters you desire.

Of course you'd need to keep the headless bodies alive by hooking them up to machines (at least initially), and deliver a steady stream of nutrients and hormones for development, but this path opens up so many new and exciting experimental pathways. It's revolutionary, but at the same time it's actually kind of simple and elegant. And once you have a facility for growing and maintaining the bodies, you can also produce new ones on site.

The kinds of experiments you couldn't ethically perform before are now broadly available. You can destroy the host immune system, delete immunogenic epitopes, build MHC libraries, etc. With thousands of bodies you could do research rapidly, in situ.

This kind of setup also revolutionizes medical testing.

If I were a billionaire, I'd be investing in this instead of space rockets. Space isn't hospitable for human bodies. We evolved for Earth. I'd wager we either have robots or change our own biological makeup before we have widespread space travel, so it makes sense to invest in the technological reverse salient rather than the flashy sci fi one. Living longer, disease free, gets us there faster.

It's more than a little macabre, but hard to argue against if it does work. A few questions:

What if embodied cognition is a bigger deal than we think it is? i.e. i) To what degree do we need an active being to develop the various organs and ii) The uncephalized body might not be that dead

One of the alternatives is using animal organs (xenotransplantation), and we now have the ability to "humanize" them by genetically removing viruses and altering their immunogenicity to decrease the chances of rejection: https://www.egenesisbio.com/technology/

If we will take the potential suffering of uncephalized humans seriously, it will be cognitively much harder to be as casual as we normally are with animal suffering.

I feel xenotransplants ethically eventually goes zero? A non cognitive shell is less sentient than a clinic rared animal with sharable organs. Xtransplants are a step up from food factory farming but doesnt do much for the rights of non-humans still.

You don't keep the animal alive indefinitely in a questionably vegetative just to grow up its organs though - you let it roam about (likely in a caged and germ free, granted, but hopefully large, facility) and when the time comes to harvest the organ, you sacrifice the animal in a humane way.

Isn't the brain responsible for a lot of the hormone levels and such necessary for proper functioning of the body? Would you really be able to grow all those organs in a body without a head?

Looks like the answer is yes https://en.wikipedia.org/wiki/Anencephaly#Organ_donation

Pretty sure you just described The Island (2005). Key point was that after failed tests without consciousness, they discovered the hosts needed consciousness to be viable.

In real life, I imagine there'd be similar needs for consciousness, or at least the movement and physical stress that a conscious human would experience. From what I understand, bones and other tissues actually require the stresses of everyday life in order to grow correctly.

We don't need the bodies to function. We need them as an organ growing environment. The muscles will atrophy, so what.

Then you cannot use the muscles, and you've just lost one the of the initial use-cases. Repeat it for any organ that need a functional body for its development and you might end up with really few useful parts from your “factory” actually.

Few is better than none, and at least for muscles, you could simulate the "stresses of everyday life" with machines.

All I see are bioengineering problems. Once we start hill-climbing this solution path all the problems will become shallower and shallower.

You can't use the animal muscles as well. What organs need moving, active body, if you can control hormone levels etc?

Well, then, can you mechanically create those stresses? Regularly send electrical signals to exercise the muscles, increase and reduce pressure and temperature (even have robot-controlled plates do a full massage), stretch and vibrate the whole setup, cycle through levels of certain hormones...? It may take some experimentation, but once you figure out a process that works, you can grow millions of organs with it.

(The story "Mazer in Prison" mentioned, offhand, someone getting his muscles electrically stimulated while he slept as a substitute for exercise.)

That is presuming human cloning is not considered unethical on its own.

Who would birth the (almost) babies by the way?

How do you sustain them to grow the organs?

We have serious trouble with keeping fully grown people in coma alive, much more with damaged neonates.

And toggling a switch can cause side effects. We still do not know enough about early development.

Or that you can keep mostly dead bodies alive by some means and not, say, get buried, cremated or taken apart for transplants.

> Or that you can keep mostly dead bodies alive by some means and not, say, get (...) taken apart for transplants.

That would actually be the reason for doing this in the first place, wouldn't it? Or did I misunderstand your comment?

Longer human lifespans would be incredibly destructive for Earth.

We need to expand beyond the Earth before messing with that stuff...

How to manage birth rates may indeed become a difficult political issue with extended lifespans. But in purely economic terms, if you could get another 40-50 years of healthy productive career out of the same human instead of having another one spend 18-26 years growing and getting expensive education and then also needing a lot of extra healthcare in the later years, then that would be an excellent efficiency improvement. Also, if individual humans routinely expect to live >100 years, then that gives them a stronger incentive to avoid choices that have a long-term negative impact.

I absolutely don't trust capitalism not to use actual humans with brains and pretend it's clone bodies because body-snatching the poor is cheaper. Or to create clones that can feel but cover it up.

I also absolutely don't trust that technology to exist around people like Epstein.

Sorry, there are genuinely things humanity isn't ethical enough for and this is probably one of them.

Should be very simple to sequence a few cells and check that they have the modifications that prevent brain development.

Should be very simple to switch the samples in the lab.

Compare how sneaky Russia gets about putting drug-addled athletes through the Olympics, and there's nothing but vainglorious national pride at stake there.

If every hospital doing a transplant were required to do a quick gene sequence verification, it'd be pretty hard to keep that conspiracy under wraps.

Not really. Right now in the present day, the Chinese are accused of using Falun Gong political prisoners as organ harvest victims. All it requires is a corrupt system, enough political power to make dissenters think twice, and buyers who will take "a new liver now" over "an ethical liver when you reach the head of the line".

Yes, a system that's corrupt at the highest levels is another matter. But a system like that doesn't have to bother with sneaky lab switches.

I'm talking about preventing abuse at the lower levels, in a country that's still doing a good job with protection of individual rights and maintaining the rule of law. Some laws are difficult for any government to enforce; this wouldn't be one of them.

Not to mention pay someone off to look the other way, etc.

How many body parts can I replace with my spare-parts-clone until I don't have anything of the original left? We have a Ship of Theseus question about human identity. As interesting as this rabbit hole is, I think the pragmatics of "you need a new body part and this will save your life" will be more compelling.

How many cells need to be regenerated for you to be a new person? The ship of Theseus is totally uninteresting to me and to be honest I think it has never been interesting. It's just calling attention to the fact that arbitrary definitions are arbitrary.

Something something "ethics" something something "no play gods"

Page is down.

Google cache copy:

https://webcache.googleusercontent.com/search?q=cache:N5sMhg...

What happened to washing the cells from the underlying collagen structure and using that as a scaffold?

Roughly ten years ago I saw a Nova Science Now episode on this and it looked rather workable, so what's the state of that?

I found a video of the episode:

https://www.youtube.com/watch?v=jLs8DeHVkec

around the 7 minute mark there is a pumping heart that was grown ontop of such a scaffold.

Oh wow, the woman in the video had to undergo a lung amputation in 2016, and everything shown in the video seems to be the culmination of a crazy amount of unscientific experimentation on a patient:

> Macchiarini admitted that one year after the operation Claudia had to be repeatedly saved with a stent in her airways, a method which worked so badly for her before. Macchiarini and his team also claimed in 2014 to have been watching over his patient “every 3 months”.

>It was however too late. In July 2016, Claudia underwent a lung amputation. Luckily, she was Macchiarini’s only trachea transplant patient in Barcelona, a second operation was stopped due to technical formalities.

Here is the full, horrifying article.

https://forbetterscience.com/2016/11/02/claudias-trachea/

Page won't load, so I can only speculate based on the title. Barring miracles, the answer is "very far off". Sure, the macroscopic structure is relatively simple. And sure, it's just a pump. But it's a pump with its own frequency generator (SA node). Which supplies blood to itself. Which is self-repairing to a large extent, in spite of the insane volumes of blood it pumps every living moment and the stresses that puts on its own blood vessels. It's an electromechanical Swiss watch, where timing is crucial and various types of tissue have various conductive properties.

Good luck with the 3D printer. Maybe start with a valve that lasts longer than a pig valve, move up from there.

Edit: nerve replacement would be a nice next step. Or simple muscle replacement. Lots of people would benefit from that, and both are likely prerequisites to "printing" a heart.

Not close. I think we'll see lab-grown meat with an identical taste get within an order of magnitude of the cost of natural meat before lab-grown tissue technology rises to the task of producing a functional heart at any price point.

We are very far from 3D printing the human heart, in fact, it will never happen. A human heart can only be grown.

Why? I mean there are no constraints to printing it at least in theory.

Usually the rule with a title that ends in a question mark is that the answer is no. In this case "not close" seems to be the answer. Rest assured, it's way more complicated and there are a lot more problems to tackle than just aligning ECMs.

That being said, I love this sort of thing so much. Maybe one day my grandkids might be saved by this.

Betteridge's law; I love this sort of thing too, though I hope it comes sooner and humanity/society breaks new ground in science at a more rapid clip (compared to the morass many believe we are currently in)

Well we kinda picked all the low hanging fruit over the last 150 years. Each technological advancement seems exponentially more expensive.

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