Perreault_Michel-SarrazinDr. Claude Perreault is an hematologist and graduate from the Université de Montréal. He works in the Hemato-Oncology Department of the Maisonneuve-Rosemont Hospital (HMR) with a team of 26 physicians where he specializes in new cases, like Dr. House from the House TV series. He sees referred patients with difficult and unusual diagnoses.

His medical career is impressive enough in itself, but could not suffice for a man like Claude Perreault. For 32 years now, he has also been directing a research laboratory in immunobiology; first at the HMR and then, since 2005, at the Institute for Research in Immunology and Cancer (IRIC) at the Université de Montréal, of which he is one the founding members. In 32 years, many changes occurred in health science research, both in general biological concepts and the experimental methods and technologies available. Today, we will take a look back with Dr. Perreault to talk about the evolution of research over the course of his career.


Maude Dumont-Lagacé: Claude, early in your career, you have chosen to do research. What motivated you to work in this field?


Claude Perreault receives his diploma in human immunogenetic from Charles Salmon (Université Paris VI), in Paris, 1980

Claude Perreault: When I began my career in the 1980s, research was not a popular option among French Quebecers. So, I made the more conventional choice to practice medicine, but realised with time that, though it is a gratifying field, something was missing for me: innovation. I recognized that to be happy in life, I needed novelty and change, and quickly found out that there was a routine side to medical practice. I also noticed that I was much more interested in patients for whom there was no treatment available than by simpler cases. Back home at night, I would think a lot more about the patients I could not help than about those I did.

I got involved in hematology because, firstly, it’s the only medical discipline that combines clinical and laboratory work, and secondly, as the doctor who recruited me said, “Claude, in hematology, you can do what no one can in other specialties: you can conduct daily biopsies on the organs you are studying and treating.” I thought that was a pretty cool idea.

So, I completed my residency in hematology. At the time, the worst disease you could encounter—a disease that is still problematic today—was acute myeloid leukemia. It’s probably the type of cancer that kills the fastest. Since I was particularly interested in difficult-to-treat diseases, it became the most interesting disease to me. Afterward, a series of chance occurrences led me to research.

Back then, blood was distributed to hospitals by the Canadian Red Cross. At one point, the employees of the Red Cross went on strike, which meant no more blood for transfusions. As a resident, I organized a blood donation clinic and I began by soliciting friends. The first friend I sought was a resident in orthopedics, a very popular guy, built like a wrestler. He told me, “Claude, your clinic will be busy. I will go and be the first. And for me, you’ll need more than one bag—you’ll need two: one for each arm!” So, I placed a tourniquet around his arm and all of sudden, his skin was scattered with small red dots. Thinking it strange, I ran a blood test. Diagnosis: acute myeloid leukemia. The disease I wanted to study and my buddy had it. Worst of all, it was akin to a death sentence at the time.


The thymus, located above the heart, is bigger in infancy than adulthood. Its size decreases with age in a process called thymic involution. By the age of 45 years in human, the thymus has lost 75% of its epithelial cells, which causes an important decrease in T cell production.

In Seattle, however, a team had started to do bone marrow transplants under the assumption that it could cure acute leukemia. In short, we organized a fundraiser and collected $100,000 to send my colleague to Seattle where he was a member of the first cohort of patients with acute myeloid leukemia to be treated by medullary transplant. To my great fascination, his leukemia disappeared after the transplant. Unfortunately, he died from a cytomegalovirus infection shortly after. That’s how I discovered the fantastic potential of medullary transplant in that it could cure leukemia, but that there was still an element we were missing. Patients undergoing such a transplant remained immunodeficient—that is, with a weakened immune system—for a long time, and we had no idea why. In hindsight, we came to two conclusions. First, that leukemia was cured due to the T-lymphocytes present in the graft. For me, that was a revelation. It was thus the immune system of the donor that rejected the leukemic cells of the recipient. Second, we learned that patients remained immunodeficient for a long time following the transplant due to thymic atrophy. When adults undergo chemo- or radiation therapy, they no longer have the thymus of a newborn, and their immune system takes longer to regenerate. It is therefore through that model that we uncovered the impact of thymic atrophy.

Those first findings are still at the core of the lines of research in my laboratory today: cancer immunotherapy and thymic ageing to understand and correct it. That’s when it gelled for me.

M.D.L.: In all that time, when did you start to do research?

C.P.: At the end of my residency, I hadn’t yet decided on research, but I knew I wanted to perform bone marrow transplants. I had to learn new techniques, including HLA typing, so I went to France to join the team of Professor Charles Salmon, an expert in human immunogenetics—that is, everything linked to transplants and transfusions. I worked with him in his laboratory and the hospital next door also performed medullary transplants (bone marrow transplants). I learned the required laboratory knowledge and received an initiation to research in immunogenetics, which I found extremely interesting.

So, upon my return to Montreal, I set up my own laboratory in histocompatibility as well as a medullary transplant unit, and partnered with two established immunologists from the Université de Montréal—Micheline Pelletier and Serge Montplaisir—to conduct research on medullary transplants. My first human research project was to study the ontogeny of a dendritic cell population from the skin called Langerhans’ cells. We did not really know what these cells were and with techniques that would be deemed rudimentary today, we studied how and at what rate the Langerhans’ cells of patients receiving a transplant were replaced by the Langerhans’ cells from the donor. We demonstrated that Langerhans’ cells were indeed hematopoietic (something we did not know back then!) and the rate at which they were replaced with new ones. We also noted that Langerhans’ cells remained very deficient in the recipient in case of graft-versus-host disease—a complication greatly feared with transplants.

Subsequently, I received my first grants and recruited a first student, Sylvie Brochu, who still works in my laboratory to this day. Little by little, my projects became more diversified and more concerned with basic research: I went from research on human samples to research on mice. About ten years ago, I moved from the research centre of the Maisonneuve-Rosemont Hospital to IRIC. It was very exciting to take part in establishing the Institute! Since then, I have met with new colleagues, particularly Pierre Thibault in chemistry and Sébastien Lemieux in bioinformatics. Over the years, I have worked with many people, but these two partnerships remain the most fruitful of my career and they continue to this day. They opened my field of research and added dimensions I did not have before. I believe that bioinformatics should now be included in the curriculum of all researchers. If you cannot use the modern computer tools, you are denying yourself an access to a wealth of data and resources. In short, I am very happy to have made that shift.

M.D.L.: Speaking of technological shift, we have seen many technologies emerge in biological research over the last decades. What are the most marked differences in technical capabilities between the beginning of your career and today?

Flow cytometry is a technique used to analyze a tissue at the individual-cell scale. To analyze each cell individually, they must be detached from each other in a cell suspension. The cytometer detects cells through lasers and identifies the inherent optical proprieties of cells (autofluorescence) or the fluorescent molecules used to mark specific cell structures, such as antibodies coupled with fluorescent molecules. Flow cytometry allows for the quantitative and qualitative analysis of thousands of cells per second, which is a much faster process than traditional microscopy.

rosettesQuantification of T-lymphocytes through rosette formationImage adapted from Liu et al, 2014. This test is conducted by incubating human lymphocytes in the presence of sheep serum and red blood cells. Sheep red blood cells (pictured in pink) attach to T-lymphocytes (in blue) in a flower-like structure, hence the name “rosette”. Reference: Liu, Wei‑Hui, et al. “B7‑H4 expression in bladder urothelial carcinoma and immune escape mechanisms.” Oncology Letters 8.6 (2014): 2527-2534.

Systems biology : A multidisciplinary approach seeking to integrate various levels of information to understand how biological systems function as a whole. In a systems biology approach to cancer research, for example, tumors are studied at various levels (DNA, RNAs, proteins, cell microenvironment, individuals, populations, etc.) and the information gathered is analyzed jointly. The analysis of such a large quantity of information (that is, the analysis of thousands of variables from hundreds of individuals!) requires the use of computer tools.
Chunking :A psychological theory advanced by George A. Miller in 1956 stipulating that human short-term memory can process seven different chunks, give or take two. Chunks represent closely linked dataset expressed in a way familiar to the subject. For example, a series of numbers like 12022015 will be easier to memorized in this form—12-02-2015—which recalls the written form of a date. In this example, eight numbers become one chunk easier for short-term memory to process. Reference: Miller, George A. “The magical number seven, plus or minus two: Some limits on our capacity for processing information.” Psychological Review 63.2 (1956): 81.

C.P.: I would say that there are two major differences. First, the advent of flow cytometry in the 1980s when I first began to do research. It was an important advance because the tests available then to study the various lymphocyte populations were extremely rudimentary. For instance, to quantify T-lymphocytes, we looked at blood samples under a microscope. We defined T-lymphocytes as a forming rosettes when in presence of sheep red blood cells. I remember attending a Keystone Symposium when immunology was just beginning to gather speed, and truly, flow cytometry was a major game changer. In addition, the ability to perform cell sorting with cytometers, which happened almost simultaneously with the development of technologies for analysis only, opened many new possibilities.

Second, the recent paradigm shift brought on by systems biology—a shift that is not over yet. Many scientists are reluctant to consider scientific issues from that angle when, in my opinion, it is now crucial to do so. Which is not to say that every question can be answered through an approach based on systems biology, but rather that it is an essential component in the study of all questions. Today, I think I could reasonably sell this concept to a group of students, but ten years ago, when IRIC was founded, it was not that obvious to everyone. IRIC was largely built around systems biology and colleagues would often tease us by saying, “High throughput, no output!”

Finally, one exciting thing that I see on the horizon is artificial intelligence. I have a feeling that this will also change how we approach research. Upon a closer look, those technologies—flow cytometry, systems biology, and artificial intelligence—represent more global and holistic ways to analyze biological systems. I often tell my new students that our brains can only handle 7 chunks, give or take two, and building an expertise means expanding those chunks bit by bit. Well, soon enough, we will have access to silicone brains also capable of building chunks to help us.

M.D.L.: Over the course of your career, you have done research on various topics and read about many disciplines. What discovery had the greatest impact on your career and changed your perspective on hematology or hemato-oncology?

C.P.: One discovery by Belgian researcher Thierry Boon has influenced me greatly. Boon was the first to define the molecular structure of a tumour-specific antigen. Put into context, at the end of the 1970s, screening was not a commodity, so we had to find other methods of analysis. Thierry Boon had discovered a tumour cell line that was rejected by T-lymphocytes in mice. That meant that the T-lymphocytes recognized an antigen specifically present on those tumour cells. To identify the antigen in question, Boon isolated messenger RNAs from the cell line and hypothesized that somewhere in this RNA, there was a gene encoding for that tumour antigen. He then transferred that genetic library to a cell line not rejected by mice. And by separating the gene library in increasingly smaller fragments, Boon managed to isolate the one single gene encoding the antigen recognized by T-lymphocytes. Since the antigen was encoded by one of the cell’s RNAs, it was a simple question of progressive elimination to identify the corresponding gene. That was an important lesson for me: even when a problem appears to be of insoluble complexity, its solution can be very simple.

M.D.L.: In a blog post for the scientific journal Nature, Richard Van Noorden noted that the global publication of scientific articles increases by approximately 9% each year, which means that the quantity of annual publications is doubled every 9 years (see Van Noorden, Richard. “Global scientific output doubles every nine years.” Nature [2014]). With so much new insights emerging, what is your strategy to keep abreast of scientific discoveries?

C.P.: First, you need to devote a lot of time to it. I must admit that personally, I have not developed much expertise beyond biology, I am not very versatile. I’d like to say that I am an artist, but really, I tend to have a monomaniacal focus, which occupies a lot of my time. Second, I make efforts to stay connected by discussing with people different from me, whether that difference be generational or of disciplines. I take much pleasure in working with graduate students. I’m currently reviewing grant applications from Europe and I decided to review applications from young researchers. I am curious about what they aim to do. To keep up with trends or, better yet, to be a trendsetter, you must stay connected and read a lot while, at the same time, allow for time to disconnect and reflect. You must distance yourself from dominant ideologies. It’s important to take the time to speak with people from other disciplines, but also to think by yourself and have fun formulating hypotheses, and then dismantling them. You must learn to construct theories but also to see them being taken apart. In short, it’s important to practice.

M.D.L.: You’ve been directing your laboratory for 32 years, so you have seen a lot. In your experience, what has changed the most over time?

C.P.: I feel like I’m learning from my students more and more. Not that I deem myself more ignorant than I used to be, but rather because I think students are better today. They have more confidence and know that international research is a highly competitive sector. It is no longer a simple question of doing your job properly in your immediate setting: students now have a much more global perspective on research.

From a social standpoint, when I look at different generations talking among themselves, I sometimes notice that people from my generation, the Baby boomers, tend to find the younger generation not as voluntarily monomaniacal in its approach than they were back in the day, that is, giving everything to their work. Many youths disagree with that approach, and I, for one, look forward to see how their more balanced vision will develop itself effectively. It would be futile to oppose a generation’s attitudes, and personally, I’m not worried. I look at the results achieved and find them really good.

maude_1Interview conducted by Maude Dumont-Lagacé
Ph.D. student in molecular biology
LResearch laboratory of Claude Perreault

Maude is studying the mechanisms of thymus regeneration. The role of the thymic epithelium is to regulate the maturation and selection of T-lymphocytes, which are crucial cells in the regulation of adaptive immunity and the elimination of cells infected by virus or cancer cells. Despite this crucial role, thymic epithelium deteriorates with age, leading to a gradual decrease in the production of T-lymphocytes, which makes the regeneration of the immune system difficult in adults following radiation therapy or a bone marrow transplant. With stem cells being responsible for tissue repair, her goal is to identify and characterize the thymic epithelial stem cells.