Artificial cells (false-color image) in a range of structures. Credit: Imperial College London

By using a special type of laser beam, researchers are able to connect, arrange and merge artificial cells in whatever structure they choose.

A team from the Imperial College London and Loughborough University have altered artificial cell membranes so that the cells stick together, enabling researchers to arrange them into new structures. This could someday be useful for drug delivery and it could allow scientists to change the composition of cells in real time to get them to adopt new functions.

“Connecting artificial cells together is a valuable technology in the wider toolkit we are assembling for creating these biological systems using bottom-up approaches,” Oscar Ces, from the Department of Chemistry at Imperial, said in a statement. “We can now start to scale up basic cell technologies into larger tissue-scale networks, with precise control over the kind of architecture we create.”

A membrane-like layer that acts as a shell enables the artificial cells to stick to each other. To achieve this, the researchers first manipulated the cells with optical tweezers, which use highly focused laser beams to provide an attractive or repulsive force.

These optical tweezers can act as mini “tractor beams” that drag and drop the cells into any position. Once connected in this way, the cells can be moved as one unit.

While biological cells perform complex functions, they are difficult to controllably engineer.

However, in principal artificial cells can be made to order. The research team was able to demonstrate a new level of complexity by arranging the artificial cells into basic tissue structures with different types of connectivity that could be used to perform functions like initiating chemical reactions or moving chemicals around networks of artificial and biological cells.

The new artificial cells could be useful in carrying out chemical reactions in ultra-small volumes, in studying the mechanisms through which cells communicate with one another and in the development of a new generation of smart biomaterials.

 “Artificial cell membranes usually bounce off each other like rubber balls. By altering the biophysics of the membranes in our cells, we got them instead to stick to each other like stickle bricks,” lead researcher Yuval Elani, PhD, an EPSRC Research Fellow from the Department of Chemistry at Imperial, said in a statement. “With this, we were able to form networks of cells connected by 'biojunctions.’

“By reinserting biological components such as proteins in the membrane, we could get the cells to communicate and exchange material with one another,” he added. “This mimics what is seen in nature, so it's a great step forward in creating biological-like artificial cell tissues.”

The researchers also engineered a “tether between two cells, where the membranes are not stuck together, but a tendril of membrane material links them so that they can be moved together.

Once they had perfected the cell-sticking process, the team was able to build up more complex arrangements like lines of cells, 2D shapes like squares and 3D shapes like pyramids.

After the cells are stuck together, they can be rearranged and pulled by a laser beam as a single unit.

The researchers were able to connect two cells and then make them merge into one larger cell by coating the membranes with gold nanoparticles. When the laser beam at the heart of the 'optical tweezer' technology was concentrated at the junction between the two cells, the nanoparticles resonated, breaking the membranes at that point. Then the membrane reforms as a whole.

The study was published in Nature Communications.