Seeing beyond the blind spots of biomedical research with super-resolution microscopy

Super-resolution microscopy as a bridge between scientific discoveries and medicine

The 21st century is considered by many as the beginning of the era of personalized medicine, a term that suggests that each patient is accurately diagnosed with the exact cause of their illness, and then matched with a precise treatment for that. This slowly becomes the reality, with diagnostic tools becoming more and more sophisticated, focusing on the cellular and the molecular levels as the keys to unlock the mechanisms of disease. With a resolution of 20 nm, super-resolution methods are excellent tools in the scientist’s toolbox to investigate molecular events within cells, including ones that could lead to disease.

One example where super-resolution tools are useful is in the case where the mechanism behind a disease lies in the wrong localization of a protein within a cell. Much of the normal activity in cells depends on trafficking of biomolecules between different compartments, for instance, trafficking of newly-made proteins from the ribosomes to the organelles where they are needed, and equally, trafficking proteins that are no longer needed into the degradation sites, the proteasomes or the lysosomes. Several diseases are characterized by mislocalization of proteins inside cells, many of which involve dysregulation of protein degradation. In a subset of Parkinson’s Disease cases, certain genetic mutations are responsible for accumulation of damaged mitochondria, which if it wasn’t for the mutations, should have been degraded. Super-resolution microscopy is ideal to study the distribution of proteins in-situ inside the cell, either in fixed cells or in living cells, including in response to different stressors. Using these approaches allows scientists to identify what proteins are mislocalized, where they end up and what it leads to. With time, treatments against these exact events can be developed.

Another example is when scientists wish to study physical interactions between proteins, which is often essential for the healthy function of cells. For instance, the timely replication of cells requires the physical association of multiple proteins that will initiate the replication process. If this association is not properly regulated, for example, due to genetic mutations, cell replication could get out of control and contribute to the formation of tumors. Super-resolution microscopy offers a myriad of methods to study and quantify interaction between proteins. A very recent paper used our Nanoimager to demonstrate that certain mutations in the protein EGFR lead to its dysregulated association, which contributes to resistance to drugs in tumors. Additionally, single molecule FRET (smFRET) is another super-resolution approach that is excellent for accurate measurements of protein interactions. Interestingly, smFRET can also be used in studies of drug discovery, as a tool to identify new drugs that disrupt disease-causing interactions between proteins.

One last example where advanced super-resolution techniques can be used in medicine is in “liquid biopsies'': identifying specific biomarkers in bodily fluids, e.g., the detection of extracellular vesicles (EVs) from a blood sample. One recent paper used the Nanoimager to detect viral SARS-CoV-2 proteins inside EVs from blood samples taken from patients. The advantage of super-resolution here is that it is compatible even with a very small sample, as is often the case with clinical samples from patients.

The molecular mechanisms of diseases often involve participants and events that are simply too small to detect in many conventional methods. With its combination of both a remarkable resolution and built-in quantitative data, super-resolution microscopy offers an excellent solution for what would otherwise be a blind spot in biological research.