Errors in mitosis that cause chromosomes to lag behind during cell division cause the formation of micronuclei. These extra-nuclear bodies containing damaged chromosomes, or chromosome fragments, are often seen in cancer cells. While structurally similar to the primary nucleus, micronuclei are much more prone to membrane rupture. And when a micronucleus ruptures, its DNA can shatter, causing genome instability and tumorigenesis.
Postdoctoral research fellow Dr. Anna Mammel of Fred Hutchinson Cancer Research Center and her mentor, faculty member Dr. Emily Hatch, wanted to learn what causes micronuclei to become unstable — information that would be critical in devising a possible strategy to prevent rupture and cancer genome instability.
To do so, Mammel and Hatch needed to image and quantify nanoscale features of micronuclei. But they didn’t know which imaging approach and microscope would work best for their needs. In addition, they wanted the highest possible resolution for 3D imaging of fixed, adherent mammalian cells, which would require super-resolution imaging — but neither had much experience with the method.
The team turned to the experts in Fred Hutch Shared Resources for help. Mammel and Hatch met to discuss the project’s challenges and goals with Cellular Imaging core Director Dr. Peng Guo and two of the core’s imaging experts, Dr. Lena Schroeder and Dave McDonald, and with image analysis expert Dr. Julien Dubrulle of the Genomics & Bioinformatics shared resource. Over several conversations, the group mapped out an appropriate course of action to get Mammel and Hatch the high-resolution images they needed and to develop a pipeline for image analysis and quantification.
Schroeder and Guo held development sessions in which Mammel tried several microscopes and compared images of her samples acquired with two state-of-the-art, super-resolution imaging approaches: instant structured illumination microscopy, or iSIM, and stimulated emission depletion, or STED. Because each sample and each research project is unique, it would have been impossible to know which technology was the best fit for the team’s needs without this valuable testing process. Mammel also benefited from the core’s expert staff members to refine sample labeling and identify the optimal imaging parameters.