Tiny shaking spheres designed to feed and multiply raise possibility of artificial organisms
Researchers say they are close to creating life from scratch after building tiny quivering blobs that use lab-made DNA to feed, grow and multiply in a dish.
According to a report in The Guardian, the synthetic cells were made from chemical compounds and would be the first to demonstrate the complete cell cycle of growth, genetic replication and division to produce the next generation.
This work raises the prospect of artificial organisms designed and built to produce medicines, foods, fuels and other materials. But it can also illuminate the deeper question of how particular assemblages of inanimate matter cross a threshold into life.
Dr Kate Adamala, who led the research at the University of Minnesota, said: “It is not as robust, as fast or as good at most of its functions as a natural cell, but it is proof of principle that the molecules can reconstitute behaviors that we have until now associated only with natural living cells.”
Scientists have been trying to create synthetic life for decades. In 2010, Craig Venter, the late genetics pioneer, constructed an organism based on a bacteria that causes mastitis in goats. Others have achieved similar feats.
Instead of modifying natural cells, Adamala’s team built SpudCells from the bottom up to ensure every component was known and understood. They started with tiny water-filled spheres called liposomes, which are a few thousandths of a millimeter wide, and added a small amount of synthetic DNA to carry out basic functions. Adamala calls them SpudCells to evoke Sputnik and the dawn of the space age, but that’s not the only reason. “I’m Polish,” she said. “I’m mostly made of potatoes.”
SpudCells operate only in a liquid packed with vital chemicals such as 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. The SpudCell genome contains further 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, outperforming the original SpudCells. Professor Tom Ellis, of Imperial College London, said the work was probably “the biggest recent advance in the field”.
“Making a synthetic cell helps us understand the exact minimum requirements for life and how life could have emerged 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.”
Watching SpudCells split was striking, Adamala said. “These are some of the most beautiful images I’ve seen, but I’m obviously biased. To most people, looking at it under a microscope, it doesn’t look like much… It’s a blob.” SpudCells are not living, but could become a chassis with which to build life, she added.
For Adamala, this work is proof of the principle that synthetic cells can behave like living cells. But they are far from being as efficient as living cells. SpudCells are entirely dependent on the substances and components of the liquid in which they are immersed. They cannot build their own protein-producing machinery, control their metabolism, or eliminate their wastes. And when they divide, they often pass on the wrong amount of DNA. They collapse after a few generations.
Adamala and others are launching an institution called Biotic to pool global expertise and transform 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” from genes and biochemistry. The study was released as a preprint, ahead of peer review, so that other labs could review 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 value of these synthetic cells and wondered whether they would be more effective in making medicines, foods, fuels and materials than engineered bacterial cells. They may not tell us much about life either, he added. “Perhaps this will provide a convincing argument against those who believe that there is an immaterial substance in addition to the chemicals that give life to material things. But almost no scientists believe this today,” he said.
“What is missing, I think, is the relational aspect of life that has become clear in the growing awareness that life is almost universally symbiotic,” he added. “If synthetic cells are used only to produce valuable chemicals, this relational aspect might be missing, just like one of the most interesting aspects of real living things.”
