Tiny quivering spheres designed to feed and multiply raise possibility of artificial organisms
Researchers say they are closer to creating life from scratch after building tiny, quivering masses that use lab-made DNA to feed, grow and multiply on a plate.
According to a report in The Guardian, the synthetic cells were made from chemical compounds and are believed to be the first to demonstrate the full cell cycle of growth, genetic replication and division to produce the next generation.
The work raises the possibility of creating artificial organisms designed and built to produce medicines, food, fuel and other materials. But it can also shed light on the profound question of how certain collections of inanimate matter cross a threshold to become life.
Dr Kate Adamala, who led the research at the University of Minnesota, said: “It’s not as robust, as fast or as good at most of its functions as a natural cell, but it is proof of principle that molecules can reconstitute behaviors that until now we only associated with natural living cells. If we want to be able to engineer biology, we really have to understand exactly the model, every component of it, to know what we are changing.”
Scientists have been trying to create synthetic life for decades. In 2010, Craig Venter, the late genetics pioneer, built an organism based on a bacteria that causes mastitis in goats. Others have accomplished similar feats.
Instead of modifying natural cells, Adamala’s team built SpudCells from the bottom up to ensure each component was known and understood. They started with small water-filled spheres called liposomes that are a few thousandths of a millimeter wide and added a small amount of synthetic DNA to provide basic functions. Adamala calls them SpudCells to evoke Sputnik and the dawn of the space age, but that is not the only reason. “I’m Polish,” she said. “I’m made mostly of potatoes.”
SpudCells work only in a liquid that is packed with vital chemicals like ATP, the main energy-carrying molecule that living cells make from nutrients. To grow, SpudCells fuse with tiny “feeder” liposomes in the liquid. These contain molecules, enzymes and microscopic structures called ribosomes that SpudCells need to make proteins. SpudCell’s genome carries other instructions for copying its genome and dividing.
To mimic the evolutionary concept of survival of the fittest, the researchers showed how SpudCells with a genetic growth advantage spread through the population, outgrowing the original SpudCells. Professor Tom Ellis, of Imperial College London, said the work was probably “the biggest advance in this field in recent times”.
“Making a synthetic cell helps us understand the exact minimum requirements for life and how life could have arisen from chemistry,” Ellis said. “It is also useful because it provides a fully understood system for testing biological circuits and computational models of cellular life.”
The split at SpudCells was surprising to witness, Adamala said. “They’re among the most beautiful images I’ve ever seen, but obviously I’m biased. To most people, looking at them under a microscope, they don’t look like much… It’s a mass.” SpudCells are not alive, but they could become a chassis with which to build life, he added.
For Adamala, the work is proof of principle that synthetic cells can behave like living cells. But they are not as capable as living cells. SpudCells depend entirely on the substances and components of the liquid in which they are immersed. They cannot build their own machinery to make proteins, control their metabolism, or eliminate their waste. And when they divide, they often pass on the wrong amount of DNA. They fall apart after a few generations.
Adamala and others are launching an institution called Biotic to pool global expertise and turn SpudCells into something more impressive. The goal, according to co-founder Professor Drew Endy, a bioengineer at Stanford University, is to build “an operating system for life” built from genes and biochemistry. The study was published as a preprint, before peer review, so that other laboratories can examine the work without delay.
Professor John Dupré, philosopher and founder of the Center for the Study of Life Sciences at the University of Exeter, questioned the point of this type of synthetic cells and whether they would be more effective at producing medicines, food, fuel and materials than modified bacterial cells. Maybe they don’t tell us much about life either, he added. “Perhaps it provides a convincing argument against those who think that there is some immaterial substance other than chemicals that gives life to material things. But almost no scientists believe this now,” he said.
“I think what is missing is the relational aspect of life, which has become clear in the growing understanding that life is almost universally symbiotic,” he added. “If synthetic cells are used only to produce valuable chemicals, this relational aspect might be absent, but so would one of the most interesting aspects of real living beings.”
