April 22, 2021

Xenobots: can you really make living robots from stem cells?

Xenobots: can you really make living robots from stem cells?


Can you really make living robots from stem cells called xenobots?

How would this work?

You take frog stem cells, supercomputers to tell you what to do with them, and you get xenobots?

Well, kind of yes and no at this point. It’s a fascinating area.

Xenobots: can you really make living robots from stem cells?
Xenobots paper in PNAS 2020 Figure4. The original legend, “Transferal from silico to vivo. The first design selected for fabrication and specific hypothesis testing (A) was the most robust yet stable and energy-efficient configuration of passive (epidermis; green) and contractile (cardiac; red) tissues found by the evolutionary algorithm. The design was evaluated 25 times for 1 min of simulation time, resulting in 25 movement trajectories (pink curves in C). Six reconfigurable organisms were built which embodied this design (e.g., B) (SI Appendix, section S9). Three were evaluated four times and the other three were evaluated five times for 10 min each (27 blue curves in C). The organisms’ direction of movement matched the design’s predicted direction of movement (P < 0.01; details in SI Appendix, section S9). To determine whether the organisms’ movement was a result of chance or due to the design’s evolved geometry and tissue placement, geometry and tissue distribution was altered by rotating the design 180° about its transverse plane (D) and evaluating it another 25 times in silico (pink curves in F). Each of the six organisms were likewise inverted (E): four were evaluated five times while the remaining two were only evaluated once (22 blue curves in F). Inverting the design significantly reduces its net displacement (P < 0.001), as did inverting the organisms (P < 0.0001).”

What are xenobots?

What does the name “xenobot” bring to mind for you?

When I think of  the root “xeno” as a scientist the meaning “foreign” or “different” comes to mind. However, in this case “xeno” refers to Xenopus as in a type of frog.

“Bot”, of course, refers to a robot.

Frog robots?

Last year so-called xenobots first appeared on the stem cell scene in a new paper. Here’s the original xenobot PNAS paper.

You can also see the researchers’ own xenobot website for more info.

Their paper generated tons of media interest including this CNN piece: Meet the xenobot: world’s first living, self-healing robots created from frog stem cells.

Usually such breathless headlines are a good indicator that something is being hyped big time.

A xenobot is defined by the authors as a living robot made from frog cells including stem cells. Here’s a video from one of the researchers on their work.

Claims about xenobots and what they can do

You can see a video presentation about them above by Josh Bongard, one of the leaders of the research. They were designed using supercomputers, which adds to the coolness factor it seems.

That original 2020 WaPo piece made some big claims:

“the machines are less than a millimeter (0.04 inches) wide — small enough to travel inside human bodies. They can walk and swim, survive for weeks without food, and work together in groups.

These are “entirely new life-forms,”

Fact-check on the claims

Let’s take a critical look at the claims in the media and the video.

Can xenobots do specific actions? It’s hard to say, but I’m also skeptical about the self-healing claim. In the video the cut xenobot is not self-healing I think. It’s just aggregating back together.

Xenobots can walk? I haven’t seen that in the videos.

They swim? Kinda.

They work together in groups? I am very skeptical about this claim. Just because xenobots aggregate or substances in a petri dish with them come together doesn’t mean they are “working” together. Recall that they have no nervous system.

Let’s dig into this a bit more and go into maybe the two biggest claims.

Are xenobots alive and are they organisms?

Since they are made of living cells, they are technically alive at a cellular level. This is akin to the way a small cluster of skin cells from a biopsy is alive for a time. Or the way a hair you just accidentally pulled out of your head is alive for some hours. However, like a clump of skin or hair or even a dab of blood, xenobots are not living organisms. They are just small clusters of cells that can hang around for some hours.

Also, they cannot reproduce.

If the researchers or other teams in this area could make similar clusters of frog cells that could self-reproduce would those be alive? That’s a good question without a clear answer.

It also gets at the much bigger question of how to define a living organism. Deep stuff.

If xenobots are living beings as claimed, then would “homobots”, equivalent robots made from human stem cells, be a form of living being? I tend to think not, but such homobots would raise many questions.

So are they entirely new life-forms as claimed? In their current form, I would say no. There’s some personification or “animalification” going on here. At one point in the video they compare xenobots to sheepdogs.

Are they safe?

The researchers have also claimed, “As biological machines, xenobots are more environmentally friendly and safer for human health, the study said.”

There’s no evidence that xenobots are safer than traditional robots or machines. It’s easy to imagine xenobots of the future running amok.

For example, if xenobots began to reproduce on their own, could they do environmental damage or get inside people and do harm? It’s at least possible. If there was an attempt to use xenobots to do things inside the human body like deliver medicines, they could easily cause problems. Xenobots are likely to be seen as foreign antigens.

What if you could make xenobots from patient’s own stem cells?

Xenobots: hype or cool breakthrough?

Sometimes it’s hard to tell the difference between a real breakthrough and just plain old science hype. In the case of xenobots I think the jury is still out.

I’d like to see more research and data. What the researchers have achieved so far is very cool and I do think there’s potential here. However, I’d say it’d be wise to be much more cautious in how xenobots are discussed.

The future of xenobots may be using micro-robots (maybe traditional ones not made from cells) to build them from specific kinds of cells and tissue instead of researchers crudely slapping them together and molding them into shape.

Then imagine making xenobots that can make more xenobots. A lot of potential and risk there.



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