Imagine a cell that can monitor health from inside the body.

Genetic engineers have created a cell that can create a log of what happens to it, encoded in its own DNA.

Using the the CRISPR gene editing technique, synthetic biologists developed the DNA-based logging system for a wide range of uses, from smart cells that can monitor health, to enhanced immune cells or sensors.

The research report is accessible here.

Researcher Timothy Lu and colleagues at the Massachusetts Institute of Technology (MIT) designed the system to allow CRISPR to be activated within a cell whenever it experiences a particular event – for example, it can be programmed to log any contacts with a particular chemical.

When it happens, the CRISPR system inserts a mutation in a specific region of DNA, which leaves a record in the genetic log marking the event.

Then by simply counting how many mutations are in a cell, a tally of the events is presented.

At the moment, the system only generates random mutations in the DNA, but the researchers say they will be able to produce a more precise record of a cell’s experiences by using a system of codes in the future.

There are plenty of things happening inside the body that are extremely difficult to spot and monitor.

But CRISPR-based logging could show what happens inside cells that turn cancerous, or simply help monitor substances in the body.

In tests so far, Lu’s team have successfully programmed cells to monitor inflammation levels in mice.

Another team used the same technique to create random mutations in zebrafish, forming a sort of identifying barcode in the cells of the developing embryo.

After injecting CRISPR proteins into the embryos, the random mutations they created were used to trace which cells formed which organs.

This allowed them to follow how a simple bundle of cells could form an entire body.

“This CRISPR-based method shows great promise,” says Australian National University geneticist Gaetan Burgio.

He hopes the technology will one day use gene activity logs to understand just what happens when a virus or bacterium invades a cell.