Defining Mechanisms of Stem-Cell Derived Neocortical Neuron Survival

The largest part of the cerebral cortex, the neocortex, is involved in the sensory processing and motor planning which are detrimentally affected by neurodegenerative diseases and injuries like Alzheimer’s, stroke, and normal aging. Because the mechanisms in neocortical degeneration are not fully understood, effective therapies are rare. In 2012, human stem cells were successfully differentiated into neocortical neurons in vitro. Blocking non-neuronal fate signaling induced neuronal, and specifically neocortical, differentiation according to the default model. For the first time human neocortical neurons could then be studied in vitro. The Brivanlou lab has previously developed assays using these neurons to observe neuronal death and survival (survival assays) which pointed to the potential benefits of neurotrophic factors (NTFs). We tested the effects of several key signaling pathways in this assay, including PI3Kinase, FGF, and RhoKinase, in order to understand the mechanisms involved in neurodegeneration. We imaged the neurons in a high throughput format at a series of timepoints. In order to ensure accurate neuronal outgrowth and cell count data, we used unbiased automated image processing quantitative analysis. Our data suggest that neither the neurotrophic factors tested, nor FGF mediated neuronal survival. On the other hand, PI3Kinase activity and RhoKinase inhibition increased survival. These results will contribute to the growing understanding of how to best maintain neurons in vitro. More importantly, our findings have the potential to shed light on how to save neurons from injury or disease.