Periodic Reporting for period 1 - BiCiCle (Biophysics of circulating tumor cells, from single molecule to cell clusters)
Berichtszeitraum: 2020-09-01 bis 2022-08-31
More than 90% of cancer-related deaths (more than eight million deaths worldwide each year) are due to the development of tumor metastasis, a complex process with multiple steps in which cancer cells spread within the patient’s body. There is an emerging realization that the fearsome transmitters of this cancer dissemination are clusters of so-called circulating tumor cells (CTC) that detach from the primary tumor, disseminate and home themselves in distant tissues. During their travel together in the bloodstream, they are subjected to important mechanical forces, for example, while passing through small capillaries. Nevertheless, the current knowledge of how these cells are held together is extremely limited.
This project aims at unravelling the biophysical properties of CTCs clusters and its dynamic changes that enable clusters to pass through small capillaries. To better understand this, we offered to characterize the adhesion forces between cells and the viscoelastic properties of individual CTC and CTC clusters using an advanced technique called atomic force microscopy.
However, this technique involves immobilizing the cells on a surface to perform the measurements, which does not correspond to the physiological state of circulating cells. We therefore sought to develop a new technique for measuring the mechanical properties of cells directly in suspension. To do so, we combined acoustic force spectroscopy, an emerging technique using sounds waves to manipulate or levitate micro-objects, and reflection contract interference microscopy, an optical technique known since decades. We have demonstrated that this unique combination allows measuring the deformation of objects in suspension.
This project aims at unravelling the biophysical properties of CTCs clusters and its dynamic changes that enable clusters to pass through small capillaries. To better understand this, we offered to characterize the adhesion forces between cells and the viscoelastic properties of individual CTC and CTC clusters using an advanced technique called atomic force microscopy.
However, this technique involves immobilizing the cells on a surface to perform the measurements, which does not correspond to the physiological state of circulating cells. We therefore sought to develop a new technique for measuring the mechanical properties of cells directly in suspension. To do so, we combined acoustic force spectroscopy, an emerging technique using sounds waves to manipulate or levitate micro-objects, and reflection contract interference microscopy, an optical technique known since decades. We have demonstrated that this unique combination allows measuring the deformation of objects in suspension.
This project allowed us to develop a new biophysical technique based on the use of standing acoustic waves to manipulate objects, such as cells, in a microfluidic channel. In this way, cells can be pushed against the wall of the microfluidic channel and their deformation can be measured optically, allowing their viscoelastic properties to be determined.
The development of this technique required overcoming the technical constraints of the acoustic and optical parts to find compromises. Calibration also proved to be challenging.
The results obtained were presented at several conferences and meetings (scientific days of local interdisciplinary institute, meetings of research network in biomechanics, conference of biophysical society, summer school of acoustofluidics). This made it possible to benefit from the feedback of the scientific community, and to confront the project with a large disciplinary panel, allowing to confront the physical, acoustic and biological points of view, to ensure that no aspect was left aside.
A manuscript is under preparation and a patent will be deposited.
This project has also contributed to training several master's students who have completed their internship in the laboratory, and several of whom now wish to continue in research and complete a PhD.
In addition, several science popularization actions aimed at scholars and the general public were carried out as part of the science festival and the European researchers’ night.
The development of this technique required overcoming the technical constraints of the acoustic and optical parts to find compromises. Calibration also proved to be challenging.
The results obtained were presented at several conferences and meetings (scientific days of local interdisciplinary institute, meetings of research network in biomechanics, conference of biophysical society, summer school of acoustofluidics). This made it possible to benefit from the feedback of the scientific community, and to confront the project with a large disciplinary panel, allowing to confront the physical, acoustic and biological points of view, to ensure that no aspect was left aside.
A manuscript is under preparation and a patent will be deposited.
This project has also contributed to training several master's students who have completed their internship in the laboratory, and several of whom now wish to continue in research and complete a PhD.
In addition, several science popularization actions aimed at scholars and the general public were carried out as part of the science festival and the European researchers’ night.
This project led to the development of a new biophysical technique. The great advantage of this technique over existing techniques is that it allows measurements under physiological conditions for circulating cells. The cells do not need to be labeled, placed in a particular medium, or immobilized on a surface. In addition, this technique opens the way to high throughput characterizations: it allows measurements to be made on several cells in parallel, while maintaining accuracy at the single cell level. This is also an advantage compared to techniques that provide an average reading that can mask individual phenomena within a cell population. Finally, this technique allows measurements to be made over long time scales. This allows the measurement of the mechanical response of cells to slow stresses that cells experience in the human body.