Unique properties of neuron-restricted progenitors derived from human stem cells
Neural stem cells are self-renewing cells that generate progenitors capable of further differentiation into functional cell types of the central nervous system: neurons, astrocytes, and oligodendrocytes. During brain formation, the stem cells of the embryonic cortex generate neurons early during the developmental process but form astrocytes at later stages, suggesting that progenitor fate potential shifts over time. Despite evidence for neuron-restricted and astrocyte-restricted progenitors, little is known about the cellular characteristics that critically differentiate these two cell types from each other. In part, this lack of understanding is due to the shortage of specific markers that will distinguish these cell types. Specific progenitors can be used for transplantation to form a particular type of final, functional cell.
Analysis of neuron- and astrocyte-forming neural stem/progenitor cells (NSPCs) by a technique termed dielectrophoresis (DEP) demonstrates that cell behavior in DEP correlates with potential to form neurons. DEP is a label-free, non-toxic and unbiased method for analyzing cells that detects formation of frequency-induced dipoles in cells. The dielectric properties of neuron- and astrocyte-forming mouse and human NSPCs significantly differ from each other and reflect their fate biases such that neuron-forming progenitors become more similar to neurons and astrocyte-forming progenitors to astrocytes. Furthermore, the specific dielectric properties of human NSPCs isolated from brain represent differences in the membrane compartments of those cells.
The goal of this proposal is to utilize DEP to determine the cellular properties that discriminate neuron-forming progenitors from other cells. We hypothesize that stem cell fate potential revealed by dielectric signature is due to the cell membrane and that modifications altering the effective membrane thickness or surface area, such as modification of certain membrane components, are the main contributors to the cell fate-specific dielectric signatures. We will test this hypothesis with neural lineage cells derived from human ES cells, iPS cells, and brain. Experiments to test this hypothesis will identify the contribution of membrane and cytoplasmic cellular compartments to cell lineage-specific dielectric properties and test the involvement of membrane modifications in progenitor cell dielectric properties. We expect that NSPC dielectric properties will be a biophysical measure of their fate potential, providing a novel approach for investigating lineage-committed NSPCs and a way to use these cells to obtain specific cell types, such as neurons, after transplantation.
The goal of this project is to determine whether a novel strategy using DEP can serve to identify specific characteristics of stem cell subpopulations. In the course of these studies, we expect to learn more about human progenitor cells that specifically generate neurons, a cell population of interest for basic biological studies, therapeutic approaches, and as a source of human neurons for drug testing. Our hope is that this label-free method for investigating stem cell subpopulations will greatly increase the speed of stem cell research in California and improve our understanding of how to control the composition of cells used in therapeutics.