Recently, researchers at the Lyon Cancer Research Center have demonstrated the potential of imaging technology to study oncology issues. Advanced imaging techniques can differentiate malignant cell populations and monitor the effectiveness of anticancer therapies. The study result is published in the Journal of Physical Review Letters, helping to design new therapeutic molecules and personalization of treatment.
Despite a good understanding of the biology of cancer, 90% of experimental drugs failed during clinical trials. Increasingly, studies have been made to investigate the mechanical properties of tumors that affect disease progression and therapeutic efficacy. However, current conventional methods cannot measure the local stiffness in depth and observing whether the tumor core resists penetration of the therapeutic fluid. In order to detect these physical properties, the researchers used a non-contact imaging technique that uses the natural infinitely small vibration imaging of the material. Since there is no need of a contrast agent, it will not interfere with tissue function.
To probe the behavior of colorectal tumors in vitro, the researchers created a 0.3 mm diameter organ-like sphere formed by the aggregation of tumor cells, and then they focused the red laser beam on these objects. The infinitesimal vibration of the sample produced by thermal agitation changes the color of the beam leaving the sample very slightly. By analyzing this light, a mechanical property map of the model tumor is created, that is, the stiffer the area of the laser scan, the faster the vibration, and the greater the color change as the distance become sharper in a way that is more in tune with the Doppler effect.
The researchers found that they can distinguish between two cell types and their mechanical properties, from organoids composed of two different malignant cell lines. This information is critical because it improves the diagnosis of biopsy analysis and provides a better assessment of tumor grade. Meanwhile, the local changes in mechanical properties after drug treatment were also monitored using this technique: the center of the tumor remained stiffer than the edge, demonstrating the efficacy gradient of the treatment. Therefore, local measurement of mechanical properties can confirm the complete destruction of the tumor and help to select the lowest possible therapeutic dose and duration.
This method allows the exploration of the effects of mechanical properties on the therapeutic response and can be used to test new predictive in vitro tumor models of new therapeutic molecules and combination therapies. In addition, it can provide new indicators to guide clinicians to individualized treatment.
Jérémie Margueritat et al. High-Frequency Mechanical Properties of Tumors Measured by Brillouin Light Scattering. Physical Review Letters, 2019; 122 (1) DOI: 10.1103/PhysRevLett.122.018101