Microscope Reveals Subcellular Activity in 3D Living Color

After a decade of work in his lab at the Howard Hughes Medical Institute, Eric Betzig has developed a microscope that presents an unprecedented picture of subcellular activity in 3D living color.

by Nancy S. Giges
June 11, 2018

A new microscope with the ability to capture detailed 3D movies of cells deep within living systems marks the culmination of Eric Betzig’s 10 years of work in the optical imaging lab at Howard Hughes Medical Institute, Chevy Chase, MD. The microscope, compared with similar tools, presents a much more realistic picture of what is actually going on inside multicellular organisms.

Trained as a physicist and awarded a Nobel Prize in chemistry, Betzig describes himself as an engineer. His lab at HHMI’s Janelia Research Campus in Ashburn, VA, is focused on developing novel optical imaging tools aimed at opening new windows into molecular, cellular, and neurobiology.

The microscope required the combination of two adaptive optical systems, including the technology used by astronomers to provide clear views of distant celestial objects through the Earth’s turbulent atmosphere, and lattice light sheet microscopy, itself a combination of techniques that builds a high-resolution 3D movie of subcellular activity.

While scientists have been able to view sharp images of living cells under microscopes for years, seeing them outside of their natural surroundings left scientists wondering if something was missing. With this new microscope and its ability to portray the most detailed picture yet of subcellular dynamics, they now know that’s true. “It’s changing the world view you have of the cell,” Betzig says.

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For Betzig, the pretty drawings of the innards of a cell in college biology books are simply a caricature of what a cell really is. “It’s so far removed from the reality of what’s going on inside the cell that it’s incredibly misleading,” he says. “We are finally getting an appreciation of that.”

He believes having that appreciation will lead to a different way of thinking about things such as drug discovery. “You have to start moving toward dynamic screens instead of just looking at fixed, dead cells, [and instead] look for changes in how the cells respond,” he says. “That’s where these tools are leading us.”

The mission statement that Betzig set forth 10 years ago was to study the cell as gently as possible in a multicellular context with high resolution in space and time, and in treatment. Betzig’s microscope is helping him to establish that goal.

Betzig developed all of the technologies used in the new microscope in the lab during the past decade. The first was lattice light sheet microscopy, published in 2014, which allowed scientists to observe live cells, tissues, and organisms without damaging them with the harsh laser light. He did that by using thin sheets of light to illuminate what is being viewed one slice at a time. This allowed researchers to view biological activity as never before in three dimensions and multiple colors. The technology, though, has some limitations.

“We knew that would be the case, but it became a good tool for studying cultured cells,” says Betzig, who is moving to the University of California, Berkeley, in the fall.

The limitations were resolved by combining the microscope with the two adaptive optical systems, advanced that same year with his publication of another paper about a new adaptive optics technology capitalizing on what Betzig describes as a “technical wrinkle that makes it more robust for biology.”

Astronomers use adaptive optics strategies to remove atmospheric distortions producing blurriness, caused by the atmosphere’s bending of light in random directions, in their images. Typically, a wavefront sensor is used to measure the distortion, which allows the telescope mirror to be adjusted to give a much clearer view of what is being observed.

The challenges that astronomers face in correcting the atmosphere are nowhere near as complex as what researchers face looking into a multi-cellular specimen, Betzig says.

“On the other hand, they must correct much faster than we do because the atmosphere flickers quickly,” he adds. “With this wrinkle we were able to get something that’s robust and reliable into multicellular systems.”

Once the team finished developing these two approaches in 2014, the next step was putting them together in a way that they work in concert, described in his most recent paper published in April in the journal Science.

With this new microscope, scientists can see a bustle of activity at the subcellular level. The team is already working on making a more compact version that will fit on a desk at a cost affordable to individual labs. The current microscope takes up a 10-foot table. The first one will go to Janelia’s Advanced Imaging Center, and scientists from around the world can apply to use it.

Since Betzig believes “technical demonstrations and publications don’t amount to a hill of beans” if people don’t use new discoveries and then make their own additional new discoveries, it seemed reasonable to ask him to be more specific about what he envisions his new microscope might lead to.

“That’s highly speculative,” he says, and then uses a video accompanying the paper to explain. The video shows three stages of human breast cancer cells moving in a capillary of a zebrafish. In the first part there is a rolling cell with long sticky microvilli behind it, kind of like sticky hands kids get in goody bags.

“It could inform you on what would happen if we target the adhesion molecules on the sticky things. Maybe we could make it so these cells can’t gain a perch and then can’t metastasize," he says. "You can imagine all sorts of things that direct observation might give you more insight into how to treat. More generally, what the lattice and the lattice in vivo is telling us is something that we knew but didn’t necessarily appreciate as much, which is that the cell is an incredibly chaotic, dynamic place, and it’s the transient inactions between its components that drive it.”

Nancy S. Giges is an independent technical writer based in White Plains, NY.

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