Researchers at the University of Minnesota have taken a significant step toward creating life from scratch by building tiny, quivering blobs called SpudCells that use lab-made DNA to feed, grow, and multiply in a dish. These synthetic cells, made from chemical compounds, are believed to be the first to demonstrate the complete cell cycle of growth, genetic replication, and splitting to produce the next generation.
Breakthrough in Synthetic Biology
The work, led by Dr. Kate Adamala, raises the prospect of artificial organisms designed to churn out drugs, foods, fuels, and other materials. It also sheds light on the fundamental question of how inanimate matter can cross the threshold to become life. '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 molecules can reconstitute behaviours that up until now we only associated with natural living cells,' Adamala said. 'If we want to be able to engineer biology, we really have to understand exactly the blueprint, every component of it, so we know what we’re changing.'
Scientists have pursued synthetic life for decades. In 2010, the late genetics pioneer Craig Venter built an organism based on a bacterium that causes mastitis in goats. Others have achieved similar feats by modifying natural cells. Adamala's team took a different approach, building SpudCells from the bottom up to ensure every component was known and understood.
How SpudCells Work
The researchers started with tiny water-filled spheres called liposomes, a few thousandths of a millimetre wide, and added a small amount of synthetic DNA to provide basic functions. The name SpudCells evokes Sputnik and the dawn of the space age, but also reflects Adamala's Polish heritage. 'I’m Polish,' she said. 'I’m mostly made of potatoes.'
SpudCells operate only in a liquid brimming with vital chemicals such as ATP, the main energy-carrying molecule that living cells manufacture from nutrients. To grow, SpudCells fuse with minuscule 'feeder' liposomes in the liquid, which contain molecules, enzymes, and ribosomes needed to make proteins. The SpudCell's genome carries instructions to copy its genome and divide.
To mimic natural selection, the researchers showed that SpudCells with a genetic growth advantage can spread through the population, outcompeting original SpudCells. Professor Tom Ellis at Imperial College London described the work as probably the field's 'biggest breakthrough in recent times.' 'Making a synthetic cell helps us understand the exact minimum requirements for life and how life might have emerged from chemistry,' Ellis said. 'It’s also useful as it provides a fully understood system for testing biological circuits and computer models of cellular life.'
Limitations and Future Prospects
Watching SpudCells divide was striking, Adamala said. 'They’re among the most beautiful images I’ve seen, but obviously I’m biased. To most people, looking at it under the microscope, it doesn’t look like much … It’s a blob.' SpudCells are not alive, but could become a chassis with which to build life, she added.
However, SpudCells are nowhere near as capable as living cells. They rely completely on substances in the liquid, cannot build their own protein-making machinery, control metabolism, or clear waste. When they divide, they often pass on the wrong amount of DNA and conk out after a few generations.
Adamala and others are launching an institution called Biotic to pool global expertise and build 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' made from genes and biochemistry. The study has been released as a preprint, before peer review, so other labs can scrutinize the work without delay.
Professor John Dupré, a philosopher and founder of the Centre for the Study of Life Sciences at the University of Exeter, questioned the point of such synthetic cells and whether they would be more effective than modified bacterial cells for making drugs, food, fuel, and materials. They may not tell us much about life, either, he added. 'It will, perhaps, provide a compelling argument against those who think there is some immaterial substance in addition to the chemicals that breathes life into material stuff. But almost no scientist now believes this,' he said. 'What is missing, I think, is the relational aspect of life which has become clear in the growing realisation that life is almost universally symbiotic. 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 actual living beings.'
