“We often have better equipment than a university hospital”

Interview with Martijn Nolte

Sanquin's Research Facility has innovative equipment that enables groundbreaking research. This equipment has a high appeal for talented researchers and grant providers. Science journalist Frank van Kolfschooten interviewed researcher Martijn Nolte.

Immunologist/hematologist Dr. Martijn Nolte is extremely enthusiastic about the technical core of Sanquin Research: the Research Facility. Spread over two floors, it houses the most advanced equipment that Sanquin researchers can use to carry out experiments on a larger and smaller scale, from tissues to cells, proteins, and other molecules. Nolte gives a tour of the three different units for microscopy, flow cytometry, and proteomics. This is where specialized technicians work who can help operate the complex equipment.

The units also have academic staff who can assist researchers with the tests and make the best use of the equipment. The tour starts at the microscopy, the unit in which Nolte works. We walk into a room where daylight is banned. At dusk, it is easier to work with the fluorescence microscopes. “Using this technique, you can light up cells in different colors by shining laser light on them,” explains Nolte. “That way, you can see how the tissue is constructed and which cell type it contains.”


Fluorescence staining of a thin slice of the spleen of a mouse. Seven different cell types can be stained simultaneously with the help of labeled antibodies.

We walk on to the unit with flow cytometers. This is where researchers who want to know more about individual cells can work. “In flow cytometers, you send thousands of cells per second along a beam of laser light,” says Nolte. “By coloring proteins on or in those cells, you can determine what kind of cell it is. We can now do this with twenty different colors at the same time, and in a few years' time with perhaps as many as thirty colors. We also have two flow cytometers that can sort four different cell populations according to the colors they have. This allows us to access the cells in a pure state and analyze them further.”

For the third unit, proteomics, we go up a flight of stairs. “Here, we analyze proteins from blood plasma or cells,” says Nolte, pointing through the window because a researcher is busy working inside. “We can use this equipment to very accurately analyze the protein composition of a sample and even to investigate whether the protein has undergone any changes.” 

Is there any crossover between the different units?

“We have recently started applying techniques and chemicals developed for flow cytometry to one of our newest microscopes. Until now, we have been able to detect three or four colors at once under the microscope, but we managed to increase that to eight. The advantage of this is that we can see from many more cell types exactly where they are located in a tissue, for example, in or just outside of a blood vessel. We also have an imaging cytometer, which combines fluorescence microscopy and cytometry and takes a photograph of every cell that passes the laser. This allows you to determine where the molecule that interests you is located, for example, on the outside of the cell or in its nucleus.

Since we can sort specific cells by cytometry, we can now also analyze their protein composition in the proteomics unit. In this way, the units are growing ever closer together. This also increases the quality of scientific publications by Sanquin researchers and their collaborators. Our researchers have already published several studies in leading scientific journals on combining microscopy, flow cytometry, and proteomics. These publications are important because they indicate to grant providers that we carry out very high-quality, groundbreaking research, and that we are experts in something that others apparently cannot yet do. That's why we do pretty well in the competition for grants. Some Sanquin researchers have received the largest European grants, and we are very proud of that.”

That’s special for a relatively small institute, isn’t it?

“Absolutely. We don’t want to boast, but we often have better and newer equipment than a large university hospital with a thousand researchers. The Netherlands Cancer Institute (NKI) is located next to our head office and closely monitors what we already have here. They regularly collaborate with us because our equipment and the associated techniques offer opportunities they do not have in-house.

My colleague Mark Hoogenboezem and a group from the NKI recently published an article in a leading magazine. In it, they describe how they have been successful in developing a cultivation system that can keep human skin alive outside the body. Using our best high-end microscope, a multiphoton microscope, Mark could analyze the behavior of T cells in human skin. Until now, this kind of testing was only possible in mice, but now it is also possible in humans. When the NKI realized how much groundbreaking research is possible using intravital microscopy, they also invested in it themselves.”

Purchasing sophisticated equipment does not guarantee success

“No—what also matters is how you use it afterwards, which questions you want to answer by using it, and ensuring that experiments are well controlled. My job is to help the scientists with this and to develop new applications for the equipment. For intravital microscopy, for example, we have developed a technique to use the multiphoton microscope in the bone marrow of living mice to see how T cells—white blood cells with an important role in the defense against viral infections, among other things—behave there in comparison with a lymph node.

T cells were found to be virtually immobile in bone marrow, whereas in a lymph node they moved very quickly. We didn't expect to find that difference. In tissue slices, you can't study these movements because by that time all of the cells are dead.” Nolte sometimes feels like a child in the playground walking around all the beautiful, state-of-the-art devices. It’s the same for Sanquin employees on the floor. They are regularly informed about the research for which the equipment at the Research Facility is used through Research-wide working meetings in the auditorium. “All of the latest developments are shown there, allowing researchers to introduce each other to new ideas.

This is also a strength of Sanquin's research focus. Here, you all attend the same meetings. In large academic hospitals, it is not always clear which techniques are available or how they can be applied. The twenty-color flow cytometer was initially used by only two people, but when the advantages of analysis using so many colors became clear, it soon became extremely popular. You now have to register well in advance to be able to work with it.”

What will be the next acquisition?

“We have now turned our attention to an even more advanced microscope, which lends itself to the application of new techniques for zooming in on tissue even more effectively. The microscope we want to buy has a very high resolution, allowing us to detect extremely small objects in living cells up to a resolution of 0.1 micrometers. If you know that the thickness of a human hair is 50 micrometers and the diameter of a red blood cell is approximately 7 micrometers, you can perhaps imagine the scale on which we can start making cells visible. This resolution can also be achieved with super-resolution microscopes, but these measurements are very slow. This new microscope not only has a high resolution, but you can also use it to take measurements very quickly and detect a lot of colors at the same time.”

A dream for every researcher

“Especially because it allows you to detect short-term contact between cells, such as how a white blood cell feeds off a tumor cell, with molecules moving from one cell to another. It is a very fast process in a very small area, which we can just about see with the current microscopes but you would want to zoom in much more.

For example, you can also study the behavior of a white blood cell coming out of a blood vessel to get to a source of inflammation. This process takes place within minutes, and we want to be able to visualize it in much more detail in order to answer questions that have been out of our reach until now. If you know how a process works, you can then change, improve, or block it, which could be useful in patients with inflammatory diseases, for instance. Thanks to a grant from the Landsteiner Foundation for Blood Transfusion Research (LSBR), the purchase of this special microscope is now within reach.”

Does this “fleet” make Sanquin more attractive as an employer? “Yes, it's a big asset in attracting talented young researchers. PhDstudents, postdocs, and even new group leaders are always looking at what they can do in a new location, whether the project suits them, and whether the institute offers sufficient technical opportunities to answer research questions. An institute that is well-equipped and has equipment that is hardly available anywhere else in the world is a really exciting place to go to. That's why I always show in detail what we have to offer here when recruiting new talent. Researchers are always pretty impressed, and it makes us very attractive to external collaboration partners (see also page 70 - ed.).

Sanquin researchers have always worked a lot with the university hospitals in Leiden and Amsterdam and with the NKI, but new collaboration partners are always welcome. For example, we are very curious to know which companies are coming to Amsterdam in the wake of the European Medicines Agency. There could be up to two thousand, and they undoubtedly include companies that are active in our field. It would be nice if they settled around Sanquin on the campus we want to create." • 

Martijn Nolte has a PhD in immunology and conducts fundamental research at the interface of immunology and hematology. He supervises other researchers and supports the application of various forms of microscopy from the Research Facility. He also teaches immunology to students and PhD students.