Using materials structured on a nanometer scale, Gaëlle Piret hopes to improve the performance of brain implants that record nerve impulses. Ultimately, the aim is to succeed in restoring certain functions to disabled people.
How do you go from pure physics to the medical prospect of brain implants?
To be honest, before my university studies, I liked all fields of science: from chemistry to biology to physics. It was curiosity that led me to choose physics. Then, for my Master's degree, I chose micro- and nanotechnologies, mainly for the cross-disciplinary aspect. It was from when I began my doctoral dissertation that I was able to bring these strands together: while my dissertation mainly concerned the fundamental questions through which the mechanisms of interaction between cells and an artificial nanostructured surface can be described, the objective was to develop an ultrasensitive method of detecting and characterizing intracellular proteins.
Then, during my postdoctoral research, I focused on nerve cells. Understanding how they interact with nanomaterials was of interest in the development of retinal implants for the visually impaired. The idea was to trap neurons on the implant for it to be functional. My research has shown that micro- and nanometric surface geometry is fundamentally important to this process, particularly to promote the adhesion of neurons and the growth of their neuronal processes and axons.
It was with this background that I joined the BrainTech Laboratory (Inserm Unit 1205) in Grenoble, where I was able to use these skills in nanotechnology. And with the Starting Grant provided by the European Research Council (ERC), I am currently working on optimizing implantable brain electrodes with a therapeutic purpose.
How do micro- and nanotechnologies make it possible to innovate in the field of brain implants?
By playing with the geometry and materials used, we can improve the growth of neuronal processes and as such improve the functionality of the implants. Thanks to the flexible and extremely fine wires and the micro-nanostructured electrodes, the implant is better tolerated, which minimizes the formation of scar tissue. In addition, the electrodes have a greater surface of exchange, which improves their ability to record neuronal signals in comparison with those currently available which have zero or low surface roughness.
This leads us to think that these electrodes could open up new perspectives. The currently existing devices enable quadriplegic individuals, after a lot of practice, to move an articulated arm that mimics the movements they are thinking about. With better performing implants and electrodes, we could conceive of capturing and carrying out more complex brain commands. People who have lost the ability to speak could, for example, transmit their cortical signals related to articulated movements enabling a vocal synthesizer to speak. This possibility is the subject of a project being developed by Blaise Yvert in our research unit.
You were awarded an ERC Starting Grant in August 2015. Tell us about your progress since then.
With this grant, we have been able to add to our skillset in the lab to speed up our development process. And it is not certain that I could have conducted this project without it: the cross-disciplinary nature of the project - which straddles engineering and biology - is complex to fund through the conventional systems.
The five-person team that I was able to put together is currently finalizing two main aspects before moving on to the pre-clinical studies. Firstly, we are trying to incorporate the materials that currently offer the best performance and so obtain micro-nanostructured electrodes made with gold or doped diamond, for example. We are also developing the microsurgery methods that will be used to implant them. To do that, given the dimensions of the implants and electrodes, we are working on encapsulating them within a biodegradable material that will facilitate their implantation and then gradually resorb to render them functional. And thanks to the ERC, we have the expertise we need to make that possible.
To find out more about Gaëlle Offranc Piret:
Gaëlle Offranc Piret works at Inserm Unit 1205 of the BrainTech research center in Grenoble whose activities are distributed among the sites of CEA-Léti, Université Grenoble Alpes and the Grenoble Alpes teaching hospital (CHUGA). She works with ESIEE (Paris), LAAS (Toulouse) and ESME (Gardanne) and leads the BRAIN MICRO SNOOPER project, ERC 640151.