Mini tractor beams help arrange artificial cells into tissue structures

A new level of complexity with artificial cells.

Image: Imperial College London

Biological cells perform complex functions. But they are critical to adjust. They are connected and capable of exchanging materials with one another. Artificial cell membranes usually bounce off each other like rubber balls.

Imperial scientists have now demonstrated the complexity with artificial cells by adding them to basic tissue structures with different types of connectivity. Such structure is expected to perform functions like initiating chemical reactions or moving chemicals around networks of artificial and biological cells.

According to scientists, sticking synthetic cells to basic tissue structure like ‘stickle bricks’ – allowing them to be arranged into whole new structures.

The video above shows one cell being dragged by the laser beam towards another cell, and the two cells’ membranes sticking together.
The video above shows one cell being dragged by the laser beam towards another cell, and the two cells’ membranes sticking together.

Scientists engineered membrane-like layer of artificial cells to stick to each other. They then manipulated the cells with ‘optical tweezers’ that act like mini ‘tractor beams’ dragging and dropping cells into any position. Doing this, the cells come close to each other.

Once they had perfected the cell-sticking process, the team were able to build up more complex arrangements. These include lines of cells, 2D shapes like squares, and 3D shapes like pyramids. Once the cells are stuck together, they can be rearranged, and also pulled by the laser beam as an ensemble.

The video above shows a fluorescing cell (brighter white outline) dragged towards a non-fluorescing cell, and a tether strung between them. The non-fluorescing cell is then dragged to the left, pulling the fluorescing cell with it.
The video above shows a fluorescing cell (brighter white outline) dragged towards a non-fluorescing cell, and a tether strung between them. The non-fluorescing cell is then dragged to the left, pulling the fluorescing cell with it.

Later on, by using gold nanoparticles to coat the membrane, scientists were also able to connect two cells, and then make them merge into one larger cell. They then user laser to at the heart of the ‘optical tweezer’ technology to connect, arrange and merge artificial cells. It causes nanoparticles within the cells to resonate and break the membrane. The membrane then reforms as a whole.

Lead researcher Dr. Yuval Elani, an EPSRC Research Fellow from the Department of Chemistry at Imperial, said: “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.

The video above shows four artificial cells brought together first as a line, then a square, then a pyramid with one cell on the top. The whole structure is then dragged together by the laser.
The video above shows four artificial cells brought together first as a line, then a square, then a pyramid with one cell on the top. The whole structure is then dragged together by the laser.

“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. This mimics what is seen in nature, so it’s a great step forward in creating biological-like artificial cell tissues.”

Professor Oscar Ces, also from the Department of Chemistry at Imperial, said: “Connecting artificial cells together is a valuable technology in the wider toolkit we are assembling for creating these biological systems using bottom-up approaches.

The video above shows two cells sticking together, with a laser shone at the interface between them. The cells then merge into one larger cell.
The video above shows two cells sticking together, with a laser shone at the interface between them. The cells then merge into one larger cell.

“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.”

According to scientists, merging cells in such structure could 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.

The study is reported in the journal Nature Communications.