Research Profile - The big picture

A team of laser experts has solved a 150-year-old problem: how to capture what's going on inside living cells without altering them in any way

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When medical researchers want to examine the tiniest components of the human body they face a very big challenge.

"Nature didn't design internal organelles (units within a cell that have specific functions) for our viewing pleasure," says Dr. Albert Stolow, a Principal Researcher with the National Research Council (NRC). "They aren't colour co-ordinated. There is little contrast. So they may all look the same when you look through a microscope."

Cells hold the key to understanding how the body functions and how disease takes root and spreads. For the past century-and-a-half, researchers who wanted to see what was going on inside a cell have used a workaround called labelling: highlighting specific areas with dyes or stains and, more recently, genetic markers. Which is great, Dr. Stolow says, except for two things:

• Researchers can't easily do this in living cells, as some dyes can be transported away or metabolized.
• The dyes and stains are chemicals that could alter the cell in some way. Genetic methods may also change things.

With funding from the Canadian Institutes of Health Research (CIHR), Dr. Stolow, NRC chemical biologist Dr. John P. Pezacki and their team tackled the 150-year-old problem by rethinking recent advances in microscopy. They succeeded beyond anyone's expectations: last fall, the Japanese optical equipment manufacturer Olympus began selling the world's first commercially available Coherent Anti-Stokes Raman Scattering (CARS) microscope using the Made-In-Canada technology that Drs. Stolow and Pezacki developed.

CARS is a process that uses nonlinear optics – the effects created when short laser pulses pass through a medium. It involves sending laser pulses down a microscope every femtosecond – one millionth of one billionth of a second – to "fingerprint" the molecular vibrations of cell components and create images of them. Discovered in 1965 – just five years after the birth of the laser – the CARS technique was further developed by U.S. scientists in 1982 and later taken up in earnest by Harvard University researchers in 1999.

The Harvard team, Dr. Stolow explains, developed a successful method that uses two lasers pulsing in extremely sophisticated synchronization. With sensitive equipment costing hundreds of thousands of dollars, the process is best done in a highly stable laboratory environment where temperature and vibration are strictly controlled.

"If you do all that, it works," says Dr. Stolow. "But it means this is not something that's easily going to go into a hospital or a clinic or a doctor's office because, first of all, it's really complicated, and, secondly, hospitals are not usually controlled environments."

That's where Dr. Stolow's team came in, coming at the problem from their particular fields of expertise: femtosecond laser technology, molecular dynamics and nonlinear optics.

"We looked at it and said, 'There must be a simpler way to do this.' The NRC bought a microscope – because we don't make microscopes – from Olympus and we told them, 'By the way, this is what we're going to do.' Then we worked out a way, using only one laser, which is much less expensive and much less sensitive to all these environmental concerns. We found a very simple way to do it."

When they were successful in capturing label-free images inside a living cell, they got back in touch with Olympus to see what reaction it would stir.

"We got an email back that said, 'How did you guys do this?' It was one of the nicest images they'd seen and they couldn't believe it," says Dr. Stolow. "They recognized that this was a good business opportunity for them."

Olympus Product Manager Dr. Yiwei Jia agrees: "Previously, the CARS method was done very expensively with special lasers and a dedicated system. The technology Dr. Stolow developed uses a regular two-photon laser and two-photon microscopy has a very wide application. It's a new technology, but there is a need for imaging live cells without labelling."

Putting the technology to work

Dr. Stolow and his colleagues at NRC decided the best business model was to enter into a partnership with Olympus to create the Ottawa CARSLab user facility specializing in the new microscopy technology (see CARSLab website).

In return for the know-how, Olympus gave NRC unique access to its microscope technology, substantial discounts on Olympus product offerings and a presence, via their web site, in the commercial microscope market. The partnership gives Canada's medical community a unique position in the optical visualization used for medical diagnostic procedures.

As part of their contribution, Olympus sponsored a reception last November so that medical researchers could get a first look at the new CARSlab and see how the technology works.

"We told them to expect about 40 or 50 people, but 200 showed up," says Dr. Stolow. "Now we're following up with researchers who work in hepatitis, neurodegeneration, heart disease, cartilage injuries, and Alzheimer's disease and telling them, 'Bring us your problems and let's try it out.'"

"The important thing is the application – making sure Canada's medical researchers know about this and how it can work for them. They'll learn for themselves where the technique will be most useful."
Dr. Albert Stolow