A new approach to modeling tumors

When researchers develop new therapies, such as for cancer, they need to be able to test them on models that closely resemble human tissue. Cell aggregates – groups of cells created in controlled laboratory conditions – represent a promising step in that direction.

The Microsystems Laboratory 4 at EPFL's School of Engineering, working in collaboration with the Ampère Laboratory at the University of Lyon, has developed a device the size of a microchip that can be used to create cell aggregates. This device employs electric fields to precisely control both the number and behavior of the cells used to form the aggregates. This study was recently published in the journal Electrophoresis.

“The utility of these aggregates can be seen in the field of electrochemotherapy, for example,” says EPFL post-doctoral researcher Jonathan Cottet, lead author of the study. In electrochemotherapy, electric fields applied to a tumor render the cell membranes permeable enough for cancer drugs to be introduced into the individual cancer cells. “But to improve and standardize this method, we need to be able to carry out tests on models that closely resemble tumors – and such models simply don't exist,” explains Dr. Cottet. “The only tests we can do at this point are at the cellular level.”

The newly developed device consists of microchannels and electrodes positioned on a plate the size of a microchip. A liquid, which in this study contained human embryonic kidney cells, flows through the microchannels. When the electric fields are turned on, the cells are “trapped” in the center of the device and form an aggregate.

“We use a technique called dielectrophoresis to trap the cells,” says Dr. Cottet. “This involves applying electric fields that attract or repel the cells depending on the properties of both the cells and the liquid.” Throughout the process, the researchers control the precise number and type of cells that circulate, selecting the ones they want to form the aggregate. Once created, the aggregate can be released without coming apart. The device was manufactured in a clean room at EPFL and is reproducible.

Cell aggregates, because they are considered permanent, are an important step towards creating organoids of a desired size and composition. Organoids are comprised of several cell types and reproduce the functions of an organ.

Researchers received the "early career researcher award" at the Dielectrophoresis 2018 conference and the "Technology Award" at the nanobiotech Montreux conference for their work.