Authors

Discussion

The ability to reprogram somatic cells to stem cells has revolutionised the modelling of human diseases in vitro. Induced pluripotent stem cells (iPSCs) can be used to generate multiple cell types found in the central nervous system (CNS), including various types of neurons, astrocytes, and microglia. iPSCs are useful for modelling neurological diseases as they can be differentiated from patient-derived somatic cells, and retain the patient’s genomic features. Mutations can also be introduced to model monogenic diseases, for example using CRISPR-Cas9. This is particularly advantageous as it allows the comparison of molecular and cellular disease phenotypes against the same isogenic control background.

At MDC, we use several techniques to examine morphological and functional changes that occur due to disease mutations or drug treatments. This includes Incucyte live-cell imaging to track the morphology and viability of disease-state neurons over time, as well as immunocytochemistry and confocal imaging to investigate changes in structural or synaptic markers. The functional activity of neurons can be assayed with calcium imaging approaches. For example, lentiviral transduction of a genetically encoded calcium indicator driven by a synapsin promoter can allow long-term Incucyte imaging of action potential firing. In addition, more traditional calcium dyes can be used, for example by loading with the calcium indicator Fluo4, allowing analysis at the single neuron level. Here we present these techniques using iPSC-derived neurons that have been engineered to have the mutation associated with Huntington’s disease, as an example of a specific disease model. These methods are invaluable to drug discovery as they further the understanding of disease phenotypes and provide a way to test therapeutics in a human system in vitro.