Research Profile – Macrophages are Red, Platelets are Blue...
Dr. Paul Kubes
Researchers at the University of Calgary are using new microscope technology to see inside live blood vessels and provide a live view of the immune system.
Researchers have long used microscopy as a tool for studying the smallest units of life. But they were generally limited to looking at cells preserved on slides. Now new advances are enabling researchers to view blood cells and bacteria as they move through blood vessels. And these advances are helping scientists at the University of Calgary (U of C) unravel important mysteries of the immune system.
Researchers there have adapted a technology called spinning-disk confocal fluorescence microscopy to look at what's inside living, active blood vessels at 1,000 times magnification.
At a Glance
Who – Dr. Paul Kubes, professor of physiology, University of Calgary.
Issue – Little is known about how the cells of the immune system function, and traditional microscopy can't be used to observe immune cells in action.
Approach – Dr. Kubes has adapted a technology called spinning-disk confocal fluorescence microscopy to study live immune cells inside blood vessels.
Impact – Dr. Kubes' group discovered that neutrophils can ensnare and kill pathogens in net-like structures. They are also using the technology to study sepsis and the airways of people with respiratory problems.
With this technology, the researchers discovered that neutrophils, a type of white blood cell, actually generate a net to catch and kill bacteria, according to Dr. Paul Kubes, professor of physiology at U of C and Director of the Snyder Institute for Chronic Diseases.
"When bacteria are present, neutrophils quickly travel to places like liver or lung blood vessels where the vessels are very narrow. They will unravel their DNA creating sticky nets, and release them into the bloodstream at these points to try to catch bacteria," says Dr. Kubes.
This sort of activity could never have been found with traditional microscopy, showing that the tools used make a big difference, he said.
The spinning-disk microscope uses multiple beams of laser light, which can penetrate skin and tissue safely. Different types of cells are tagged with a gene or compound that reacts to a particular frequency of light. When a specific type of cell that has been tagged is hit by a specific wavelength of light, the tag glows a unique colour.
"We can have, for example, green neutrophils, red macrophages, blue platelets and yellow bacteria," Dr. Kubes said.
It is akin to standing on the side of a river and being able to clearly see the fish swim by and make out which types of fish there are, according to Dr. Kubes.
His focus is using the specialized microscope for studying the immune system. The work is important because when infections occur and bacteria or viruses are present in the blood, nobody really knows exactly how all the various immune cells deal with them, or even how the cells interact with each other. But the mysteries are now starting to be solved.
Dr. Kubes' group found not only that neutrophils can ensnare and kill bacteria with their net-like structures, but also that these 'nets' can capture HIV. Will there be a way to enhance that activity to help HIV patients? That's not known at this point, but could be an intriguing direction for research.
A big part of Dr. Kubes' work is in investigating sepsis – a potentially deadly medical condition where a bacterial infection in the blood causes a whole body immune response. Severe sepsis is the leading cause of death in patients in intensive care units.
"Understanding how the immune system eradicates blood of different pathogens will be important for learning strategies for preventing a septic or blood poisoning situation where all your organs get infected, and you die of sepsis," he said.
The researchers are also working on highly miniaturized versions of the spinning-disk microscope and placing them on the tips of bronchoscopes – a type of tube that is inserted into the airways to look at the lungs.
"We're putting the bronchoscope into the airways of these patients and trying to see the vasculature," says Dr. Kubes. It was also tried on one patient who was having ongoing, uncontrollable problems with asthma.
"When we went in with our experimental bronchoscope to look at her breathing passages, we found a membrane growing that wasn't supposed to be there. With surgical removal, she's now perfectly fine," he said.
It demonstrates that this technology can be used clinically, as well as for research.
"We can have, for example, green neutrophils, red macrophages, blue platelets and yellow bacteria."
– Dr. Paul Kubes, University of Calgary