The best laid plans of mice & men

The Journal spends the day with Canada Research Chair Ann Croy to discover the world of animal research

Dr. Ann Croy (middle) with University veterinarian Andrew Winterborn (right) and staff member Valerie Barrette.
Dr. Ann Croy (middle) with University veterinarian Andrew Winterborn (right) and staff member Valerie Barrette.

From her ninth-floor office in Botterell Hall, Ann Croy has a bird’s-eye view of Queen’s campus. But despite sightings of a peregrine falcon—an endangered species that keeps visiting the lakeside building—Croy has her sights set on animals a little closer to the ground.

For almost 40 years, Croy has conducted research using mice.

In 2004, she was named a Canada Research Chair in Reproduction, Development and Sexual Function in the department of anatomy and cell biology. Today, she and her team research immune-deficient pregnant mice to look for ways to improve fetal and maternal health in humans. When I arrived at her office on Monday morning, Croy took me for a quick tour of some of her labs. In the first room, she showed me a $20,000 refrigerator used to store mouse cells collected over the years. The department has a backup freezer in case the equipment breaks, Croy said, in which case the cells—some up to 20 years old—would have to be transferred very quickly.

Next I saw the histology area, where students use microtomes to cut specimens of mouse tissue into paper-thin sections. In the third room, I saw tissue-processing equipment and an embedding station, where samples of mouse tissue are combined with cells from other mice and humans.

There were no real rodents in sight, but I did notice a toy mouse wearing a Croy Lab T-shirt sitting on top of a shelf. In Croy’s office, the windowsill is lined with an impressive collection of mice figurines.

But when it comes to actual mice, Croy said she tries to keep emotional distance. Although her staff like to name the mice in their telemetry lab—I met one called The Brain—she said she never gives them names.

Animal research has changed a lot over the years, Croy said. In the late 1960s, when she started as a veterinary medicine student at the University of Guelph, researchers often used animals from shelters. Today, conditions are much stricter—and I can vouch for that.

For one thing, I’m not allowed to say where the Croy Lab keeps its mice. Croy’s telemetry lab, where immune deficient mice—some fitted with $3,000 radiotransmitters—are impregnated, is securely monitored.

Croy herself doesn’t spend much time with the mice these days. She said she usually only visits them a few times a year, or if there are major problems. So along with University veterinarian Andrew Winterborn, it was Valerie Barrette, a member of Croy’s staff, who introduced me to the tiny creatures—but only after I signed a contract promising not to divulge their location.

Before we entered the animal holding facility, I had to put on a lab coat and squeeze a pair of cloth booties over my own boots. We walked down a long hallway lined with closed doors, most of which had dark red windows because, according to Dr. Winterborn, mice aren’t equipped with receptors to absorb red wavelengths of light. The darkness makes the mice more comfortable—they are even provided with tiny, dark red domes for their sexual endeavours.

When we came to a door at the end of the hall, I put on a new pair of sterilized shoes—these ones plastic—as well as an autoclave gown, a surgical mask, a hairnet and some latex gloves. Despite our attire, Barrette had to sterilize the metal surface of a special lab bench—the laminar flow workbench—before she could take one of the mice out of the cages lining the walls. Winterborn said the telemetry lab is likely cleaner than most hospitals.

Barrette, who trained as a veterinary technologist at St. Lawrence College, usually spends about an hour with the mice in the telemetry lab every day. She said the radiotransmitters—which sit just under the skin of the mice—have such frequent and accurate blood pressure readings that the lab can use fewer mice than it would otherwise need.

When a mouse gives birth, Barrette needs to be there to supervise—even on the weekend.

“Mostly because the animals are so important and so expensive, I have to be basically on-call,” she said, adding that because the gestation period for a mouse is between 19 and 21 days, it’s usually easy to predict when the birth will take place.

The University purchases its mice from one of five major suppliers worldwide. While most of Croy’s mice come from the Jackson Laboratory in Maine and are in the $70 range, some mice that have taken years to genetically modify can cost up to $100,000 each, Winterborn said.

Generally, the Croy lab receives 40 per cent of its funding from the federal government, 40 per cent from the provincial government and 20 per cent from the University.

After leaving the telemetry room, we watched through a window as Jianhong Zhang, another one of Croy’s colleagues, performed a tiny ultrasound on a mouse. Winterborn said the not-so-tiny ultrasound machine, which is about a year old, cost more than $75,000. Mice require the specialized equipment because their abdomens are only about 3 centimetres, so the probe used for a human ultrasound goes too deep.

We watched as the anesthetized mouse had its paws taped to a plate that used electrocardiography to monitor blood flow. As a tiny fetus showed up on the screen, Zhang also looked at respiration and heart rate.

“It’s not invasive at all—it’s just like humans,” Winterborn said.

When I asked, Winterborn wouldn’t reveal how many mice researchers at Queen’s use, nor would he say what other kinds of animals are housed in the research labs on and off-campus.

“It’s really to protect the animals that we have here,” he said, adding that the University also studies animals outside of holding areas, at the Queen’s University Biology Station and in field studies.

Wherever they are, though, the University’s Animal Care Committee watches over the steps researchers take. The committee follows federal guidelines and provincial legislation, including the Animals for Research Act. Anyone whose name appears on a protocol document has to go through animal ethics training, Winterborn said, which includes an online course and workshops.

Another thing the University has to consider is what to do with the mice after research is complete. After a female mouse gives birth and is in the weaning process, she’s euthanized. Winterborn said the mice are incinerated, with potentially harmful leftovers placed in a freezer and sent out as biohazard material.

Croy told me the mice are biohazardous because a cell used in experimentation might have human hepatitis in it. She said one lab she worked in was notified three days after it began working with a blood sample that the blood was HIV-positive.

Croy’s work with mice began with the nude mouse, the first immune-deficient mouse ever known. The mouse is unique because it has no thymus—the gland that controls the immune system. She has also done a lot of work with the Severe Combined Immunodeficiency (SCID) mouse, which has neither T-cells nor B-cells and has a functional impairment in Natural Killer (NK) cells. These deficiencies mean the mouse can be injected with human cells or tissues to model the human immune system.

But Croy isn’t all about mice. Since 1988, she’s also been working with pigs at the University of Guelph, where she worked full-time until 2004. Pig research is less destructive than work with mice, she said, because the leftovers go into traditional food processing.

In 2002, Croy began working with human cells, as well. The Croy Lab recruits women in their first trimester of pregnancy and runs assays on their blood samples in all three trimesters, as well as six weeks after they give birth. Croy said she’s particularly interested in women who have Type I diabetes, as well as pre-eclampsia, an acute rise in blood pressure that can occur midway through pregnancy.

“We don’t know what causes it, but the current hypothesis is systemic inflammation of all your blood vessels,” she said.

If Croy renews her Canada Research Chair, it will be 2019 by the time it runs out.

“I would be 73 years old—so that’s why I just think that I’m not so sure I want to keep going that long,” she said. “I just don’t think I’m brilliant enough to keep going.”

A quick glance at her 47-page C.V. would suggest otherwise. In 2007, Croy was one of the organizers for a meeting on placenta research, which brought 430 people from 37 countries to Kingston. Since 1973, she has authored 195 publications and supervised a sizable number of undergraduate students, PhD candidates, postdoctoral associates and visiting scientists. She’s had students from Poland, Iran, China, Libya, Malaysia, Scotland, Japan and Cuba.

“People come to my lab because they want to learn to work with mice,” she said. “The point of using mice is the genetics are so powerful that you can ask very precise questions.”

Croy, who has recently been asked to do a lot of work concerning national and international policies, said there are probably about 300 people worldwide leading reproductive immunology labs.

“I still think that I do what I do because I think that … reproduction is the essence of a species,” she said. “The animals aren’t always [just] a model for me—often there’s a direct reason to help the animals.”

And although she can see retirement down the road, it’s clear that Croy has a lot more research she wants to accomplish first.

“You kind of live these ideas,” she told me. “They’re always there.”

Please see next Friday’s Journal for Part Two of A Day in the Life series.

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