How should ‘mirror life’ research be restricted? Debate heats up

This week in Manchester, UK, scientists will be deliberating whether to restrict research that could eventually enable ‘mirror life’ — synthetic cells built from molecules that are mirror images of those found in the natural world.

Mirror-image molecules separated using workhorse of chemistry

Over the past year, many scientists have voiced concerns over experiments that might lead to the creation of such cells, suggesting that they would pose an enormous risk to human health and the environment. “Pretty much everybody agrees” that mirror-image cells would be “a bad thing”, says John Glass, a synthetic biologist at the J. Craig Venter Institute in La Jolla, California.

But there are disagreements about where to draw lines to limit research on mirror-image biology, given the potential benefits of such studies.

Many of the molecules in our bodies are ‘chiral’ — that is, they take one of two mirror-image (MI) forms, like right-handed and left-handed gloves. Proteins are built from left-handed amino acids, and DNA twists like a right-handed screw, for example.

Studying MI versions of such molecules could help to unpick how this handedness emerged, some researchers say. And because the body’s enzymes and immune system might not as readily recognize right-handed amino acids or left-handed DNA, such molecules could resist degradation — making them useful as therapeutic drugs. This approach has already shown clinical success: in 2017, for example, the US Food and Drug Administration approved a small peptide containing MI amino acids, called etelcalcetide, to treat people with chronic kidney disease.

Rare ‘ambidextrous’ protein breaks rules of handedness

But this ability to evade degradation could be a double-edged sword. If an entire MI cell were ever made, it might proliferate uncontrollably in the body or spread unchecked through the environment, some researchers say.

This is why scientists are meeting in Manchester this week.

Biochemist Sven Klussmann, founder and chief executive of Aptarion Biotech in Berlin, which is developing short strands of therapeutic MI RNA, agrees that it’s reasonable to consider the potential risks of mirror life. “But we should not panic yet, and we should not restrict research too early,” he says.

Yet Kate Adamala, a synthetic biologist at the University of Minnesota, Minneapolis, cautions that the risks of research that could enable mirror life would outweigh any potential benefits. “There is no benefit of mirror biology that couldn’t be achieved other ways with normal biology,” she says. “That’s not a risk I think we should be taking.”

Red lines

Glass says that several teams, including his own, are close to, for the first time, creating a synthetic cell from molecules with the chirality seen in nature. But nobody is currently building an MI cell, and it could take decades to do so, if it’s even possible at all. Still, researchers are making progress on technologies that could underpin that work; and in 2019, before the potential risks were realized, the US National Science Foundation awarded research grants to ‘boot up’ a mirror cell. Adamala, one of the grant recipients, says her growing concerns convinced her and her colleagues to drop the work.

Mirror-image enzyme copies looking-glass DNA

Glass and Adamala were among 38 scientists who laid out their worries in Science in December 2024¹. Since then, the non-profit Mirror Biology Dialogues Fund has sponsored a series of meetings to develop recommendations to avert the threat mirror life could pose. In June, researchers who gathered in Paris called on funders not to support work on an MI cell, and suggested restricting areas of research that could facilitate mirror life. In Manchester this week — and at a US National Academies of Science, Engineering and Medicine meeting at the end of this month — researchers will pick up the conversation and deliberate over where to draw those red lines.