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A new instrument makes available an innovative approach to fluorescence microscopy, opening up new possibilities for life science researchers.

Leica Microsystems, one of the world’s biggest microscope manufacturers, has launched a new instrument built around an invention devised nearly 20 years ago by from 51³Ô¹ÏÍø’s Department of Physics. The microscope, called Viventis SCAPE, offers researchers a rapid way of making three-dimensional images of cells and living tissues, and is gentler to the sample than existing fluorescence microscopy techniques.

“Using this technique, you can look at dynamics in biology, things like heart muscle cells beating as you electrically pace them or calcium dynamics in neurons,” Professor Dunsby explains. Another option is to look at lots of samples in a short period of time. “My lab has used this technique to look at arrays of specimens, as a way of generating better statistics about the biology.”

In fluorescence microscopy, samples under examination are treated with fluorescent markers that bind to substances of interest, such as specific proteins. Alternatively, the sample is genetically engineered so that it expresses fluorescent proteins. These markers give off light up when a laser beam is shone into the sample, showing structures within cells or tissues, or the biological processes underway. 

The problem with standard techniques for creating 3D fluorescent images, such as confocal microscopy, is that the laser light can destroy the fluorescent molecules or damage the sample, making it hard to observe biological processes as they unfold over time. This has led researchers to develop alternative techniques, such as light sheet fluorescence microscopy, which involves shining a thin sheet of laser light through the sample. 

“That is really gentle, because you are only illuminating the plane that you are imaging at any given time,” says Professor Dunsby. 

This method is, however, a bit cumbersome. You need to have two lenses mounted at 90 degrees to one another, one to produce the light sheet and one to observe the fluorescence. Then, in order to make a 3D image, you have to move the sample up and down through the light sheet.

Professor Dunsby’s innovation was to devise a way that one lens could both deliver the light sheet and observe the fluorescence produced, together with a remote means of moving the light sheet through the sample. This not only simplified the microscope assembly, but meant that conventional sample mounts could be used.

He patented his invention, called oblique plane microscopy (OPM), and published the results in 2008, at which point other researchers started to build on his idea. One of these was Professor Elizabeth Hillman at Columbia University in New York, who devised a way of using OPM to scan samples very rapidly, an approach she calls swept confocally aligned planar excitation microscopy, or SCAPE for short.

Leica licensed the patents for both OPM and SCAPE, and has now brought them together in the Viventis SCAPE instrument.

Meanwhile, Professor Dunsby’s lab has continued to develop and apply OPM. “For example, we’ve had a Cancer Research UK Accelerator grant applying this technology to imaging cancer spheroids and organoids,” he says. “These are small balls of cells, and the idea is that they are a better model of how real tissues behave compared to thin layers of cells grown flat on plastic or glass sheets.”

These organoids can be used to study the behaviour of cancerous tissues under different conditions, or to test potential treatments without involving animals.

On the technical side, Professor Dunsby has developed a variant of OPM that lets you look at a sample from more than one direction. “This gives you two views of the sample, which you can fuse together to give an image with more uniform spatial resolution,” he says. This innovation has also been patented.

Slideshow credits: images one and three in collaboration with the Parsons Lab, King’s College London; image two in collaboration with the Behrens and Salbreux Labs, Francis Crick Institute; image four in collaboration with the Riglar Lab, 51³Ô¹ÏÍø.