A groundbreaking microscope has been developed that allows for live imaging of biological processes in such fine detail that it can capture moving protein complexes.
In Nijmegen, researchers have installed the world’s first microscope capable of live imaging biological processes in great detail, revealing moving protein complexes. This advanced microscopy technique was created by a team under the leadership of Nico Sommerdijk at Radboud University Medical Center. As a showcase for this pioneering method, Sommerdijk is currently demonstrating the onset of arterial calcification.
Previously, scientists had to choose between using a microscope that provided detailed images at the molecular level but only worked with frozen, static samples and another that could observe living samples, albeit with much less detail. The researchers at Radboudumc have developed a technique that merges both methods, opening up new applications for the future, such as visualizing how the COVID-19 vaccine penetrates a cell or capturing the early stages of arterial calcification.
Protection
There were several technical hurdles to overcome. “To view protein complexes in such intricate detail, you need an electron microscope,” says Nico Sommerdijk, Professor of Bone Biochemistry at Radboudumc. “However, the electron beam can harm both the biological material and the fluid around it, which is not ideal for observing natural processes over longer periods.”
The proposed solution is to encase the material in a protective layer to minimize the damage caused by the electron beam. This can be done using graphene, a remarkably strong material consisting of a single layer of carbon atoms. “But as soon as this layer is applied, the biological processes you want to observe begin almost immediately,” Sommerdijk explains. “You then have to rush to the microscope, find the exact area in the tissue, and set the microscope up. This usually takes at least half an hour, and often the process is over by the time you’re ready.”
Calcification
Sommerdijk and his team have come up with a strategy to overcome these challenges. They first coat the tissue in a layer of graphene and then freeze it instantly to stop any biological activity. After that, they use a light microscope to find the precise location in the tissue they want to observe. Once the right orientation is established, they transfer the sample to the newly created electron microscope, which can measure in liquid. This setup allows them to warm the sample again, reactivating the biological processes, which can then be visualized at the nanoscale.
As an illustration of the new technique’s capabilities, Sommerdijk and his team are currently demonstrating how calcium deposits can form in ways that may contribute to arterial and aortic valve calcification. PhD candidate Luco Rutten explains: “When there’s an excess of calcium phosphate in the bloodstream, a specific protein can attach to it, stopping it from precipitating. The kidneys then remove it. Under the microscope, we observe these proteins forming tiny spheres with calcium phosphate, which are still breakable. However, these spheres can also enlarge, leading to calcium phosphate developing into calcified deposits that can no longer be broken down.” This occurrence could lead to calcification within the body.
Heart valve on a chip
At present, there are no treatments available for calcified aortic valves other than complete valve replacement. “We don’t fully understand what happens during this type of calcification, which is why there isn’t any medication yet,” remarks Sommerdijk. He plans to investigate this further using the new microscope and has recently been awarded an ERC Advanced Grant to aid in this research. He aims to create a “heart valve on a chip.” Initially, this will model a healthy valve, which he will then induce calcification in. This project is set to commence in 2025.
