THE RISE OF LIVING MACHINES
Biological robots could start solving our problems
Synthetic biologists have been redesigning life for decades now, but so far they’ve mostly been messing about with single cells – a kind of souped-up version of genetic modification. In 2010, Craig Venter and his team created the first synthetic cell, based on a bug that infects goats. Four years later, one of the first products of the synthetic biology era hit the market, when the drug company Sanofi started selling malaria drugs made by re-engineered yeast cells.
Today, though, biologists are starting to find ways to organise single cells into collectives capable of performing simple tasks. They’re tiny machines, or as biologist Josh Bongard at the University of Vermont refers to them, ‘xenobots’. The idea is to ‘piggyback’ on the hard work of nature, which has been building tiny machines for billions of years.
Currently, Bongard’s team makes its xenobots with ordinary skin and heart cells from frog embryos, producing machines based on designs etched out on a super-computer. Just by combining these two types of cells it designed machines capable of crawling across the bottom of a petri dish, pushing a small pellet around and even cooperating. “If you build a bunch of these xenobots and sprinkle the petri dish with pellets, in some cases they act like little sheepdogs and push these pellets into neat piles,” Bongard says.
Their computer runs a simple evolutionary algorithm that initially generates random designs and rejects over 99% of them – selecting only those designs capable of performing the required task in a virtual version of a petri dish. As Bongard explains, the scientists still have to turn the finished designs into reality, layering and sculpting the cells by hand. This part of the process could eventually be automated, using 3D printing or techniques to manipulate cells using electrical fields.
You couldn’t yet call these xenobots living organisms, though, as they don’t, for example, eat or reproduce. Since they can’t utilise food, they also ‘die’, or at least decompose, and quickly, meaning there’s no obvious hazard to the environment or people. However, combining this approach with more traditional synthetic biology techniques could lead to the creation of new multicellular organisms capable of performing complex tasks. For example, they could act as biodegradable drug delivery machines, and if made from human cells, they would also be biocompatible, avoiding triggering adverse immune reactions. But that’s not all. “In future work,” says Bongard, “we’re looking at adding additional cell types, maybe like nervous tissue, so these xenobots would be able to think.”