Access success story - ICFO

Throwing light on multicellular tumour spheroids (ICFO)

In a very recent project, Corinne Lorenzo from the Institute of Advanced Technologies in Life Sciences (ITAV, Toulouse, France) visited Pablo Loza-Alvarez’ lab at LASERLAB-EUROPE partner ICFO in order to try and image biological model systems used to study tumour cell proliferation. The results of Lorenzo’s two visits in February and March of this year are so promising that two other research groups joined the collaboration and a benchmarking toolbox is currently being developed.

The Super-resolution Light Microscopy & Nanoscopy (SLN) Lab at the Institute of Photonic Sciences (ICFO, Barcelona) has a Selective Plane Illumination Microscope (SPIM), which has the potential to image at large penetration depths and in scattering tissue. Having met at several conferences on SPIM microscopy, Lorenzo and Loza-Alvarez had discussed the possibility of using ICFO’s SPIM microscope to image Lorenzo’s MultiCellular Tumour Spheroids (MCTS) with the aim of retrieving the entire three-dimensional information of these samples. Loza-Alvarez, on the other hand, was interested in the elaboration of a benchmarking protocol in order to determine under which illumination conditions an absorptive and scattering tissue is best imaged. Having heard of the LASERLAB-EUROPE Transnational Access Programme, Lorenzo decided to apply for access in December of 2012 and one month later she had received the final decision granting her two visits to the SLN lab.

MCTS are 3D culture models with attractive advantages for investigation of cell proliferation in a multicellular context, as they display the organization of a tumour microdomain. However, due to their opacity and density, spheroids form highly challenging imaging samples for light microscopy and therefore represent, in terms of optical properties, a bona fide tissue paradigm.

The major issue addressed in the project was to find the optimal light sheet for 3D imaging of MCTS. To this aim, the ‘Multi SPIM’ microscope at ICFO was used and a variety of engineered fixed MCTS samples prepared by the IP3D group at the ITAV. The Multi SPIM is able to work in the linear and non-linear regime and under Gaussian or Bessel beam excitation schemes. SLN@ICFO is the only lab worldwide where such imaging techniques are available and allow a straight-forward comparison of the imaging capabilities of all different light sheet modalities.

Given the potential seen in this experiment, Lorenzo and Loza-Alvarez are now also working in collaboration with two associated groups: the Département Optique Théorique et Appliqué at Onera (Toulouse) and the Quantitative Image Analysis Unit at the Paris Pasteur Institute. All groups have complementary skills and expertise in cancer biology, cell imaging, image processing, biophotonics and optics.

Schematic of the experimental multimodal light sheet setup running at ICFO used to image multicellular tumor spheroids (MCTS) grown by ITAV. The size of the MCTS is of 400micrometers in diameter.

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