Correlative microscopy reveals abnormalities in type 1 diabetes

Microscopy has been of great value for studying the regulation of life and disease at the level of cells and molecules. Our lab routinely uses an approach to record large-scale electron microscopy (EM) data, called nanotomy for nano-anatomy. A database with donor material from type 1 diabetes (T1D) patients was created to study the disease pathogenesis at high resolution. However, the vast amount of data is only in grey scales and therefore difficult to analyze. With correlated light microscopy and EM (CLEM), molecules are specifically identified with fluorescence which is subsequently put in high resolution context using EM. The aim of this thesis was to develop novel CLEM probes and targeting approaches to, amongst others, improve the analysis of nanotomy data. The focus was on affinity-based labels to identify endogenous targets. Upon labeling of already embedded EM material with quantum dots combined with a newly developed ‘colorEM’ approach, abnormal cells with both exocrine and endocrine characteristics were identified in nanotomy datasets of islets of Langerhans from both a T1D rat model and patient donor material. First results from a functional follow up study suggest that damaged exocrine cells can possibly induce a pro-inflammatory reaction by insulin producing beta cells in early onset T1D. In summary, this thesis first provides an overview of recent CLEM developments including a guideline. Furthermore, efficient labeling on EM material was optimized in combination with improved detection methods, which led to new insights to T1D pathogenesis.