New Microscopy Technique to Witness Animal Cells in Native State
Organisms live by means of the complex, dynamic, three-dimensional (3D) interplay between millions of components, from the molecular to the multicellular. The living cell contains dynamic, spatially complex subassemblies that are sensitive to external perturbations. To minimize such perturbations, cells should be imaged in their native multicellular environments, under as gentle illumination as possible.
However, the optical heterogeneity of multicellular systems leads to aberrations that quickly compromise resolution, signal, and contrast with increasing imaging depth. Furthermore, even in the absence of aberrations, high resolution and fast imaging are usually accompanied by intense illumination, which can perturb delicate subcellular processes or even introduce permanent phototoxic effects.
Therefore, a collaborative team of scientists have now combined two imagining technologies, namely, lattice light-sheet microscopy (LLSM) and adaptive optics (AO), in order to design a novel microscope that allows for the capture of 3D video of cells at work in unprecedented detail.
Lattice light sheet microscopy uses rapid and repeated sweeps of the ultrathin sheet of light to capture a series of 2D images to build 3D movies of living cells as they carry out their functions sans
the bleaching and damage linked to traditionally focused beams of light.To unscramble the light sheet that passes through the biological structures, the researchers used adaptive optics technology, which is also used by astronomers to get a clear view of celestial objects through a turbulent atmosphere.
“Studying the cell on a coverslip is like watching a lion in the zoo—you’re not exactly seeing their native behaviors,” says physicist Eric Betzig. Using the new microscope “is like watching the lion chase an antelope on the savanna. You’re finally seeing the true nature of cells.”
Betzig, who won the Nobel Prize in Chemistry in 2014, led a team from the Howard Hughes Medical Institute Janelia Research Campus that combined these two older microscopy techniques and three separate microscopes to create the powerful new “frankenscope.”
The microscope has been used to peer inside blood vessels being invaded by cancer cells and capture white blood cells while they chomp down on sugars inside a fish eyeball. In one stunning video, the team uses the technique to “explode” the cells of a zebrafish eye, allowing the viewer to step into the spaces between the millions of cells that make up the organ.
“For the first time, we are seeing life itself at all levels inside whole, living organisms,” said Tom Kirchhausen, PhD, co-author on the new study, a senior investigator in the Program in Cellular and Molecular Medicine at Boston Children’s Hospital and a professor of cell biology and pediatrics at Harvard Medical School (HMS).
“Every time we’ve done an experiment with this microscope, we’ve observed something novel- and generated new ideas and hypotheses to test,” Kirchhausen said, “It can be used to study almost any problem in a biological system or organism I can think of.”
The structure of a cell makes it hard for anything to get in or out without the cell’s permission, and all the other cells and tissues surrounding it makes it hard to get a clear view, as these structures can scramble the light passing through. By parsing the cells with slices of laser light and then correcting for any obstruction with the same AO technique astronomers use to correct blurriness in observations of stars, the scientists have come up with a microscopy technique that looks like an artistic rendering.
The next big step is making that technology affordable and user-friendly. “Technical demonstrations and publications don’t amount to a hill of beans. The only metric by which a microscope should be judged is how many people use it, and the significance of what they discover with it,” Betzig says.
Unfortunately, you won’t see a microscope like this in your school science lab anytime soon. The tech is complicated, expensive and cumbersome; but maybe within 10 years, Betzig says, this type of imaging will be more accessible to biologists. Until then, grab a microscopic bag of popcorn and enjoy the show.
