From now on, live cells will keep no more secrets. Scientists will be able to see first-hand how they function, including how their organelles interact and react to stimuli. Nanolive, an EPFL spin-off founded in 2013, has just developed a groundbreaking microscope that lets researchers watch living cells directly, continuously, and without harming them. That paves the way to important discoveries about biological processes that until now have been insufficiently understood because of the lack of a reliable way to observe them. The company’s new system comes together with a proprietary software for converting the images in 3D and making them easier to interpret, such as by displaying specific organelles in color.

Observing cells for hours, days or weeks

With this next-generation microscope, called CX-A, scientists can watch living cell populations and zoom in all the way down to individual organelles with a resolution of <200 nm. Samples are prepared by placing the cells on a special 96 well plate. Scientists can rapidly set up their experiments by simply specifying how often they want images to be taken; the device then runs on its own. Data can be collected this way for as long as needed, with thousands of images taken over a period of several days or weeks. As a result, they can obtain unprecedented insights into how biological processes work, how organelles interact, and how mitochondria form intricate networks, for example.

The technology was initially developed by Nanolive’s CEO Yann Cotte while he was a PhD student at EPFL. It works like an MRI machine that generates images of cells from all angles using their refractive index and then compiles 3D images with the help of an advanced software. A rotating laser illuminates the sample at a 45° angle to produce a hologram, providing a unique look into cells under natural conditions. The method is non-invasive, manipulation-free, and interference-free, and the rotational scanning allows for 3D reconstruction with excellent resolution.

Traditional microscopes require the addition of stains or markers to cells, in order to add contrast and visualize them. Unfortunately, these compounds damage cells and cause them to die prematurely, shortening the length of time during which measurements can be taken. Nanolive’s technology requires no stains. “With our microscope, scientists can run experiments under a range of conditions and obtain high-quality images without adding fluorescent markers,” says Mathieu Frechin, head of quantitative biology at Nanolive. “The images generated using refractive index and the possibility to combine them with fluorescent signals enable scientists to follow over time dynamic and delicate cell processes – such as the membrane potential – of living subcellular structures like mitochondria. The signals reveal subtle variations in structure and activity that occur in response to drugs or genetic mutations.

Source: École Polytechnique Fédérale de Lausanne