Researchers at Heidelberg University in Germany used an imaging technique called soft X-ray tomography to obtain highly detailed 3D images of the interior of cells, including changes that occur when the cell is infected with SARS-CoV-2. The approach can provide a high-resolution 3D image in minutes, which is much faster than other microscopy techniques that achieve a similar level of detail.
Imaging technology is constantly improving, and our corresponding understanding of the inner workings of our cells is increasing. From identifying what happens when SARS-CoV-2 enters a cell to developing new treatments for cancer, being able to image cellular processes is important in increasing our understanding and paving the way for new therapies.
Current cell imaging techniques can struggle to create nanoscale images within a timely period, slowing down research. “Scanning electron microscopes are preferred in cell imaging because they provide extremely sharp nanoscale images,” said Venera Weinhardt, a researcher involved in the study. “But this technology takes a good week to scan an individual cell. It also generates an enormous amount of data that is daunting to analyze and interpret. Using soft X-ray tomography, we get usable results within five to ten minutes.”
So far, the Heidelberg team used the technique to study lung and kidney calls that are infected with SARS-CoV-2, and have been able to identify changes in specific cell organelles in response to infection, along with clusters of viral particles on the cell surface. In fact, they were able to identify organelles which had been hijacked by the virus to reproduce. Happily, the technique works in ‘fixed’ cells, which are those that have been immersed in a preservative solution that deactivates the viral particles, making the samples safer to work with.
The research team was able to obtain unprecedented 3D images because they changed the design of the sample holder from a flat lattice to a cylinder. The flat lattices were not optimal because they frequently caused blurry artifacts, and did not allow for scanning of samples from every angle.
“To get around this problem, we switched over to cylindrical thin-wall glass capillaries to hold the samples. During microscopy, the samples can be rotated a full 360 degrees and scanned from all angles,” said Weinhardt.
Study in Cell Reports Methods: Using soft X-ray tomography for rapid whole-cell quantitative imaging of SARS-CoV-2-infected cells