Biotech & Life Sciences

Scientists Built a Synthetic Cell That Divides—But Experts Say It Isn’t Alive Yet

The SpudCell, assembled from nonliving parts at the University of Minnesota, completes a full division cycle but breaks down after five generations.

In a lab at the University of Minnesota, a tiny blob eats, grows, competes, divides, and replicates, nearly everything a living cell does. Called the SpudCell, its makers say it is the first synthetic cell to complete a full cellular life cycle. The announcement earlier this month drew a mix of shock and awe, with many asking whether science had finally created synthetic life. The honest answer, researchers say, is close but not quite.

The SpudCell, described in Scientific American on July 14, largely resembles a living cell, with a lipid membrane and a small genome, even though it was stitched together from a list of nonliving ingredients. It can perform basic cellular functions, but it falls short of life. It needs a lot of outside help to keep going, and even then it cannot maintain its life cycle for more than a few generations. The work is detailed in Scientific American’s report.

The reason it breaks down may come down to a crucial internal structure called the ribosome. Michael Jewett, a bioengineer at Stanford who was not involved in the project, explains the ribosome is a cell’s “molecular machine,” the part that translates genetic instructions into proteins. If DNA is the cookbook and RNA is the recipe card, the ribosome is the chef that makes the finished dish. The SpudCell has no chef of its own.

What the SpudCell can and cannot do

The SpudCell’s genome carries instructions for feeding, growth, copying, and division, but not for building ribosomes from scratch. Instead the cell borrows ribosomes from the bacterium Escherichia coli, delivered by researchers through tiny droplets called liposomes, along with lipids and nutrients. Those borrowed ribosomes keep protein production going for a while. But after five rounds of division they deteriorate, and the cells start “limping along a little bit,” said Aaron Engelhart, a geneticist and cell biologist at the University of Minnesota who worked on the project. “We’re not able to get them to undergo successive rounds of division and behave as they did in the beginning.”

Exactly why the cells falter is an open question. Jewett suggests dilution could be the culprit: as the synthetic cells grow and split, their ribosomes may spread too thin until there are too few biological chefs to keep things going. Faulty inheritance may also be the problem. Because the SpudCell’s genome is split across several separate pieces of DNA rather than one molecule, some cells fail to inherit a complete set of genes. After five rounds, only about 30 percent of the cells inherited a full copy of the original genome, according to findings reported on the preprint server bioRxiv and not yet peer-reviewed.

The divide itself is simpler than nature’s. A living cell splits through an exquisitely choreographed process; the SpudCell splits because proteins crowd its membrane until the stress peels it into two. The inside of a real cell has everything packed against everything else, but in an organized way, Engelhart said, and reproducing that order is both tricky and a really important piece of the puzzle. The SpudCell lacks that organization, so when it divides, the pieces may be distributed haphazardly.

Why “not quite alive” can still be useful

The SpudCell also cannot rebuild its own ribosomes, because it lacks the genes to do so. Engelhart says future work may add those genes, but building a ribosome from scratch is, in his words, a whole field in and of itself, involving dozens of proteins and RNA strands coaxed to assemble in the right order. Even if the SpudCell is not alive, it does not have to be fully self-sufficient to be useful.

Jewett points out there are plenty of applications, such as drug delivery and diagnostics, that do not need a cell that fully rebuilds itself. He cites a water test from his own lab: a cell-free system embedded with genetic programming that changes color in the presence of contaminated water. From an engineering view, the system only needs to run its circuit once, not indefinitely. “You don’t actually need a synthetic cell,” he said. “You actually just need to be able to capture or harness the biological processes of living organisms.”

“We’re pretty far away from something that’s fully self-replicating,” Jewett said, but being able to build cells from the ground up could help researchers truly understand what a cell is. The SpudCell is a milestone not because it is alive, but because it is the closest assembled-from-scratch system yet to completing a real cellular life cycle, and because it exposes exactly where the line between chemistry and life still lies. Work like this sits alongside other synthetic-biology advances Frontierbeat has tracked, including new methods for building biology from the ground up and the broader push to apply machine learning to scientific discovery.

FAQ

What is the SpudCell?

It is a synthetic cell built at the University of Minnesota from nonliving chemical components, with a lipid membrane and a small genome. Its makers say it is the first synthetic cell to complete a full cellular life cycle, including division and replication.

Is the SpudCell alive?

Researchers say no. It borrows ribosomes from E. coli rather than building its own, needs heavy outside support, and after about five divisions only about 30 percent of cells inherit a complete genome. It cannot sustain its life cycle, so experts do not consider it alive.

What could it be used for?

Even without full self-replication, synthetic cells like the SpudCell could help with drug delivery and diagnostics, where a one-shot biological circuit is enough. Building cells from scratch also helps scientists understand what a cell fundamentally is.