Scientists Create Artificial Cells Capable of Sensing and Responding to Changes in Their Environment

A team of researchers at Imperial College London, UK, has created micromachines that sense and respond to external chemical signals through activation of an artificial signaling pathway.

Hindley et al created artificial cells that sense calcium ions and respond by fluorescing. Image credit: Zehua Hu / Imperial College London.

Responding to chemical changes is a crucial function of biological cells. For example, cells can respond to chemicals by creating certain proteins, boosting energy production, or self-destructing. Chemicals are also used by cells to communicate with each other and coordinate a response or send a signal, such as a pain impulse.

However, in natural cells these chemical responses can be very complex, involving multiple steps. This makes them difficult to engineer, for example, if researchers wanted to make natural cells produce something useful, like a drug molecule.

“These systems could be developed for use across biotechnology,” said James Hindley, first author of the study.

“For example, we could envisage creating artificial cells that can sense cancer markers and synthesize a drug within the body, or artificial cells that can sense dangerous heavy metals in the environment and release selective sponges to clean them up.”

The artificial cells created by Hindley and colleagues have smaller cells (‘vesicles’) inside. The edge of the cell is formed of a membrane that contains pores, which allow calcium ions to enter. Inside the cell, the calcium ions activate enzymes that cause the vesicles to release particles that fluoresce.

Activated by calcium, an enzyme alters the membrane of a vesicle, causing it to release fluorescent particles through the protein channel.

“We created a truncated version of a pathway found in nature, using artificial cells and elements from different natural systems to make a shorter, more efficient pathway that produces the same results,” Hindley said.

The system is simpler because it doesn’t need to account for many of the things cells need to get around in natural systems — such as by-products that are toxic to the cell.

Within the system, the membrane pores and the enzymes activated by calcium are from existing biological systems — the enzyme is taken from bee venom for example — but they would not be found in the same environment in nature.

This is the strength of using artificial cells to create chemical responses — they can more easily mix elements found apart in nature than they can add an external element into an existing biological system.

“The plug-and-play aspect of our system means researchers can take elements from across nature to create new chemical pathways designed with specific aims in mind,” said Professor Oscar Ces, senior author of the study.

“Our template system is also easy to set up and can be used to quickly test any new combination of elements researchers come up with.”

The findings were published in the Proceedings of the National Academy of Sciences.

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James W. Hindley et al. Building a synthetic mechanosensitive signaling pathway in compartmentalized artificial cells. PNAS, published online August 1, 2019; doi: 10.1073/pnas.1903500116