If reproduction is the hallmark of life, then the world’s first ‘living robots’ may have just stepped out of a petri dish in Burlington, Vermont. Admittedly, ‘stepped out’ may be overstating it, (the AI-designed ‘xenobots’ rolled around unceremoniously in the dish instead) however, they did manage to achieve something quite remarkable in the process. The tiny Pac-Man-shaped creatures gathered up frog stem cells from the solution in which they were swimming and built copies of themselves – and the magnitude of that can’t be overstated.
The team responsible for the development – from the University of Vermont, Tufts University, and the Wyss Institute for Biologically Inspired Engineering at Harvard University – built on research they unveiled last year when they created the first-ever robots constructed entirely out of living cells (the cells used being taken from frog embryos). Although these initial robots were purely organic in structure, they weren’t considered living organisms as they had no ability to self-replicate – one of the most fundamental characteristics of a living creature.
That all changed this year.
In a bid to bring life to their xenobots, Sam Kriegman, Ph.D., co-leader of the team, engaged the AI at the University of Vermont and asked it to design a xenobot parent structure. ‘The AI came up with some strange designs after months of chugging away,’ says Kriegman, ‘including one that resembled Pac-Man. It’s very non-intuitive. It looks very simple, but it’s not something a human engineer would come up with. Why one tiny mouth? Why not five?’
Despite questions over the AI’s proposed design, these results were nonetheless used to build a parent xenobot. This parent managed to build children and went on to build grandchildren. Scary stuff – not just that we’ve created a self-replicating robot, but that another one we built (an AI) designed it for us. ‘People have thought for quite a long time that we’ve worked out all the ways that life can reproduce or replicate,’ says Douglas Blackiston, Ph.D., who assembled the xenobot parents, ‘but this is something that’s never been observed before.’
Now, the idea of man-made, self-replicating creatures might send shivers down some people’s spines, however, we don’t need to worry about Pac-Man-styled invaders seizing control of the planet just yet. The self-replication system used by the xenobots isn’t fully realized, with the process dying out after a few generations. Nonetheless, the implications of this biotechnological advance are hugely profound, especially when it comes to medicine.
Xenobots and Regenerative Medicine
Regenerative medicine is a term that covers treatments that target damaged tissues, concentrating largely on selective cell replacement and repair. With its main purpose being rejuvenation, it’s often thought of as anti-aging medicine. However, what’s holding us back from developing it effectively is our inability to accurately tell cells what we want them to do.
The work being done at the University of Vermont just took us a lot closer.
The embryonic frog cells that the xenobots gathered would normally have developed into frog skin, however, in the hands of the Vermont team, the cells were retasked. ‘We’re putting them into a novel context,’ says Michael Levin, Ph.D., co-leader of the research. ‘We’re giving them a chance to reimagine their multicellularity.’
Although the cells had the genome of a frog, they were freed from any predetermined biological path and could use their collective genetic intelligence to achieve something else entirely. ‘We are working to understand this property,’ says Bongard. ‘It’s important, for society as a whole, that we study and understand how this works.’
Indeed. When you couple our increasing understanding of cell structure with the ability of an AI to create biological tools to order, we may soon have far more control over our own cells than we’ve ever had before – the research being done by the Vermont team granting us the ability to combat the ravages of cellular aging and increase human longevity.
‘If we knew how to tell collections of cells to do what we wanted them to do, ultimately, that’s regenerative medicine,’ says Levin. ‘That’s the solution to traumatic injury, birth defects, cancer, and aging. All of these different problems are here because we don’t know how to predict and control what groups of cells are going to build. Xenobots are a new platform for teaching us.’
Making Anti-Aging Technology a Reality
At this early stage, it’s hard to truly grasp the potential applications of xenobots. ‘All we can do is consider the advantages this technology has over traditional robots,’ says Bongard, ‘which is that they are small, biodegradable, and happy in water.’ While that might make them good for farming, cultured meat production, or low-cost water desalination, there’s little question that anti-aging technology will be one of the main areas of future research. The prospect of banishing age-related illnesses to the history books is sure to be tempting enough for any research team before you even think about the financial rewards.
Regenerative medicine may not be on the horizon quite yet, but with the advent of self-replicating xenobots, we’ve certainly taken a huge leap toward it. With the possibility that our own cells can be retasked to combat the hallmarks of aging, not only will we live longer, but we’ll be able to enjoy it more – you could stay fit and pretty well into your three-hundreds. So you might want to take Pac-Man a little more seriously next time you play it because its cousin, the xenobot, could be bringing the elixir of life to you in the not-too-distant future.
1. R. D. Kamm et al., Perspective: The promise of multi-cellular engineered living systems. APL Bioeng. 2, 040901 (2018).
2. D. Blackiston et al., A cellular platform for the development of synthetic living machines. Sci. Robot. 6, eabf1571 (2021).
3. J. Losner, K. Courtemanche, J. L. Whited, A cross-species analysis of systemic mediators of repair and complex tissue regeneration. NPJ Regen. Med. 6, 21 (2021).
4. S. Kriegman, D. Blackiston, M. Levin, J. Bongard, A scalable pipeline for designing reconfigurable organisms. Proc. Natl. Acad. Sci. U.S.A. 117, 1853–1859 (2020).
5. V. Zykov, E. Mytilinaios, B. Adams, H. Lipson, Robotics: Self-reproducing machines. Nature 435, 163–164 (2005).
6. Z. Qu et al., Towards high-performance microscale batteries: Configurations and optimization of electrode materials by in-situ analytical platforms. Energy Storage Mater. 29, 17–41 (2020).
7. Q. Wu et al., Organ-on-a-chip: Recent breakthroughs and future prospects. Biomed. Eng. Online 19, 9 (2020).
8. E. Garreta et al., Rethinking organoid technology through bioengineering. Nat. Mater. 20, 145–155 (2021).
9. Y. Han et al., Mesenchymal stem cells for regenerative medicine. Cells 8, 886 (2019).
10. S. F. Gilbert, S. Sarkar, Embracing complexity: Organicism for the 21st century. Dev. Dyn. 219, 1–9 (2000).
11. G. S. Hussey, J. L. Dziki, S. F. Badylak, Extracellular matrix-based materials for regenerative medicine. Nat. Rev. Mater. 3, 159–173 (2018).